Here you will find the latest and most frequently asked questions about various elements
A hydrogen atom is made of one proton and one electron. Because hydrogen has one proton, it has an atomic number of one. It is the only element whose atoms don't have any neutrons. Helium has an atomic number of two; helium has two protons, two neutrons, and two electrons.
If by "biggest" and "smallest", you mean mass (which is a measure of how much matter is there), then the smallest is the hydrogen atom with one proton and one electron. Since electrons are about 2000 times less massive than protons (and neutrons), then the mass of an atom is mostly from the protons and neutrons.
A hydrogen atom is an atom of the chemical element hydrogen. The electrically neutral atom contains a single positively charged proton and a single negatively charged electron bound to the nucleus by the Coulomb force.
The HECA project will generate clean low-carbon electricity by transforming fossil fuels into clean hydrogen that provides reliable, ongoing energy to the grid. Renewables such as wind or solar typically produce intermittent electricity that is available approximately one third of the time. Since our society’s demand for energy is constant, we can only rely so much on wind and solar energy. For this reason, HECA will produce a stable and predictable source of low-carbon electricity. In fact, HECA will generate enough clean electricity for 160,000 homes while it produces lower air emissions than any conventional plant of its size.
The primary reason to use liquid helium is that it is cold. Super cold. At normal atmospheric pressure, liquid helium boils at at temperature of just 4.2 Kelvins (-452.11 Fahrenheit).
The helium balloon displaces an amount of air (just like the empty bottle displaces an amount of water). As long as the weight of the helium plus the balloon fabric is lighter than the air it displaces, the balloon will float in the air. It turns out that helium is a lot lighter than air.
Moses Chan, Evan Pugh Professor of Physics at Penn State, explains that the world’s supply of helium is a byproduct of natural gas production, with the Texas Panhandle arguably being the helium capital of the world. However, says Chan, “Very few natural gas wells in the world have enough helium in the well to make it economical to separate helium from natural gas. The gas wells with the most helium have only about 0.3 percent, so it is in short supply.” In response to the element’s scarcity, the United States has been stockpiling helium since the 1960s in a National Helium Reserve called the Bush Dome, a deep underground reservoir outside of Amarillo, Texas. By the mid 1970s 1.2 billion cubic meters of the gas was stored there. The current reserve is approximately 0.6 billion cubic meters, or roughly 4 times the current world market. Read More
Because helium is lighter than air it is commonly used to fill airships, blimps and balloons. As it doesn't burn or react with other chemicals, helium is relatively safe to use for this purpose. While hydrogen is 7% more buoyant than helium it has a much higher fire risk.
You can drink some alcohol while taking lithium, but you must not get dehydrated. If you drink alcohol, you can continue to drink some alcohol while taking lithium but drinking alcohol can make you dehydrated.
Scientists have gained insight into why lithium salts are effective at treating bipolar disorder in what could lead to more targeted therapies with fewer side-effects. Bipolar disorder is characterised by alternating states of elevated mood, or mania, and depression.
Lithium affects the flow of sodium through nerve and muscle cells in the body. Sodium affects excitation or mania. Lithium is used to treat the manic episodes of manic depression. Manic symptoms include hyperactivity, rushed speech, poor judgment, reduced need for sleep, aggression, and anger.
Lithium is usually taken every day for a person's lifetime. Bipolar disorder can be managed but not cured.
Beryllium dust enters the air from burning coal and oil, and eventually settles over land and water. Beryllium can also enter water from erosion of rocks and soil, and from industrial waste.
Beryllium exposure varies among different segments of the population. The general population is exposed to normally low levels of beryllium in air, food, and water. People working in industries where beryllium is mined, processed, machined, or converted into metal, alloys, and other chemicals, may be exposed to high levels of beryllium. People living near these industries or near uncontrolled hazardous waste sites may also be exposed to higher than normal levels of beryllium.
The health effects associated with beryllium exposure depend on the amount and length of exposure. Beryllium can be harmful if you breathe it. If beryllium air levels are high enough, breathing it in can result in an acute condition called acute beryllium disease, which resembles pneumonia. Individuals who become sensitive to beryllium (beryllium sensitization) and develop an allergic-type reaction may contract Chronic Beryllium Disease (CBD), an inflammatory reaction in the respiratory system. CBD can cause weakness, fatigue, difficulty breathing, and can also result in anorexia, weight loss, and, in advanced cases, right side heart enlargement and heart disease.
Long term exposure to beryllium can increase the risk of developing lung cancer. The Department of Health and Human Services (DHHS) and the International Agency for Research on Cancer (IARC) have determined that beryllium is a human carcinogen (cancer-causing). However, the U.S. Environmental Protection Agency (EPA) has determined that beryllium is a probable human carcinogen.
Boron appears to act similarly in humans and mammals in the following respects:
a) Once ingested, borates are almost completely absorbed in the gut and appear rapidly in the blood and body tissues.
b) In mammals, boron is distributed evenly throughout the body fluids. Unlike soft tissues and blood, bone takes up boselectively to give levels more thanfour times higher than in blood serum. Boron also remains longer in bone, befelimination.
c) Boric acid is not metabolised (transformed) within the body. Thus the types and relative amounts of boron-containcompounds in the body will be the same in all mammals. This facilitates comparisons between work with humans and other mammalian species.
In laboratory animals, boron mainly affects the reproductive system and the development of the fetus. In rats, the no-observed-adverse-effect level (NOAEL) for boron intake is 9.6 mg/kg body weight per day. The first effect which becomes apparent at greater intake level is reduced fetal body weight. At a boron intake level of about 13 mg/kg maternal body weight per day, the weight of rat fetuses is slightly reduced, and rib anomalies may be present. At approximately 55 mg/kg body weight per day rats experience changes in the testicles and become sterile. In the rabbit, malformations of the heart and the circulatory system can be seen at boron intake levels of approximately 25 mg/kg body weight per day. In the mouse, fetal body weight can be affected at approximately 80 mg/kg body weight per day.
The primary source of both boron and borates is the mining of boron-containing minerals such as colemanite, ulexite, tincal, and kernite. Only certain deposits can be mined economically. These are located in arid regions of Turkey and the USA, and also in Argentina, Chile, Russia, China, and Peru. The total world production of boron minerals was approximately 2 750 000 tonnes in 1994. About 250 000 tonnes of boron, corresponding to 800 000 tonnes of boron oxide (B2O3), was present in commercial borate products manufactured from these minerals.
Boron is present in the environment in boron-containing compounds called borates. Borates dissolved in water can adsorb onto, and desorb from, the many different surfaces found in rivers and streams. The amount of borate adsorption depends on the water’s pH and the concentration of borate in the water. Borates dissolved in water are very stable, and do not react with oxygen or other chemicals which may be present in the water, or undergo changes from one type of borate to another. Also, animals and plants are not able to convert borates from one form to another by biological processes. Read More
The study of all compounds that contain carbon is called organic chemistry. Carbon atoms are unique. They can combine with each other to make molecules that contain hundreds, even thousands, of carbon atoms. There are more CARBON COMPOUNDS than compounds of all the other elements put together.
Everything on earth is made up of combinations of different elements – all of which can be found on the periodic table. Considering that the periodic table contains 118 elements it seems a pity that organic life tends to feature only five or six of those elements in any vast quantities. The main one being carbon.
Carbon forms the key component for all known life on Earth. Complex molecules are made up of carbon bonded with other elements, especially oxygen, hydrogen and nitrogen, and carbon is able to bond with all of these because of its four valence electrons. Carbon is abundant on earth.
Carbon is distributed very widely in nature as calcium carbonate (limestone). Coal, petroleum, and natural gas are chiefly hydrocarbons. Carbon is found as carbon dioxide in the atmosphere of the earth and dissolved in all natural waters. Read More
No, in fact, nitrogen is very inert and extremely safe. Nitrogen is the most commonly used chemical in the USA. It is used for storing and packaging of snack foods, coffee, and other food items. It does not support combustion, which is why it's used in race cars and aircraft tires.
Yes. Nitrogen will help maintain proper inflation in your tires and reduce the number of faults detected by the TPMS.
No! All the Nitrogen is extracted from the air we breathe, which is about 78.1% nitrogen to begin with. There are no nitrogen cannisters, bottles, or cylinders to worry about.
Nitrogen is an essential element of all amino acids. Amino acids are the building blocks of proteins. Nitrogen is also a component of nucleic acids, which form the DNA of all living things and holds the genetic code. Nitrogen is a component of chlorophyll, which is the site of carbohydrate formation (photosynthesis).
Nitrogen fixation is a process in which nitrogen (N2) in the atmosphere is converted into ammonia (NH3). Atmospheric nitrogen or molecular dinitrogen (N2) is relatively inert: it does not easily react with other chemicals to form new compounds.
Oxygen levels are commonly measured by two techniques. The first is a blood gas in which a blood sample is taken directly from an artery. This is the most accurate assessment of oxygen. The normal oxygen level using this technique is 80-100 (mmHg). The second technique is bloodless and is called pulse oximetry. The result here is not a direct measurement of oxygen but rather represents the percentage of hemoglobin that is saturated with oxygen. Hemoglobin is a protein in the blood that carries oxygen to the tissues. A light sensor is used which is commonly placed on a fingertip. Pulse oximetry is not as accurate as a blood gas and can be influenced by temperature and circulation. The normal oxygen saturation is 95-100%.
There are some very specific situations in which it can be harmful to be on too much oxygen. However, for most people with chronic obstructive lung disease or COPD who receive oxygen through a nasal cannula, the answer is no, too much oxygen won't hurt you. Using too much oxygen is wasteful and can cause dryness and other discomforts.
Dyspnea, or the sensation of difficult breathing does not always correlate well with the amount of oxygen (O2) in the blood - so oxygen levels may be fine, but breathing is hard. When O2 levels are okay and you may feel like you "can't breathe," your dyspnea is likely caused by anxiety (often caused by the feeling of not being able to breathe)...it is a vicious cycle.
The brain regulates breathing based on the amount of carbon dioxide in the blood. Some individuals with very severe COPD retain carbon dioxide in their blood and the brain begins to then regulate breathing based on the amount of oxygen in the blood. Giving such a person too much oxygen can actually turn off their drive to breathe and cause life threatening respiratory arrest. Therefore, people with very severe COPD should check with their healthcare provider about whether they are at risk for this type of reaction to too much oxygen.
Initial studies showed a 60% reduction in caries in fluoridated communities (communities which had appropriately adjusted fluoride to the water source). More recently, the benefit appears to be 30-40%. The difference may be attributed to use of fluoridated toothpaste and the prevalence of fluoridated water in packaged foods and beverages.
Topical fluorides strengthen teeth already present in the mouth. Fluoride is incorporated into the surface of teeth making them more decay-resistant. Fluoridated drinking water probably has a topical effect as well as a systemic effect. Systemic fluorides can give topical protection because ingested fluoride is present in saliva, which continually bathes the teeth. Fluoride is incorporated into the tooth surface to prevent decay. Fluoride also becomes incorporated into dental plaque and facilitates further remineralization. It reduces the solubility of tooth enamel in acid. It reduces the ability of plaque organisms to produce acid. Adults may also benefit from fluoridation, particularly those with receding gums, which expose the tooth roots that are particularly susceptible to decay. In addition to reducing tooth decay, water fluoridation prevents needless infection, pain, suffering and loss of teeth; improves the quality of life; and saves vast sums of money in dental treatment costs.
Over 50 years of research and experience have shown that fluoridation at optimal levels does not harm people or the environment. Leading scientists and health professionals, numerous professional organizations, and governments around the world support community water fluoridation.
While the opponents to community water fluoridation may be well intentioned, there is no scientific basis on which anti-fluoridationists base their claims. There is no credibility within the scientific community to support the scare tactics or faulty research used in the literature which opponents to community water fluoride use. Those who would benefit most from treating the rampant decay caused by non-fluoridated water are the biggest proponents for fluoride’s removal from public water. The overwhelming majority of medical and dental practitioners in our community have indicated their support of retaining fluoride in our community water supply.
Neon can be obtained from air by fractional distillation. The first step in fractional distillation of air is to change a container of air to a liquid. The liquid air is then allowed to warm up.
Neon was discovered by Sir William Ramsay, a Scottish chemist, and Morris M. Travers, an English chemist, shortly after their discovery of the element krypton in 1898. Like krypton, neon was discovered through the study of liquefied air.
Neon and argon gas by themselves are not. They are inert. As with standard fluorescent tubes, the minute droplets of mercury present in some colors are safe as long as the tube is not broken. Improper handling can be a threat to both the environment and health. Many modern neon shops refuse repair of broken argon-mercury tubes for this reason. Neon is powered by voltages in the 2,000 to 15,000 volt range. Even though the current is in the milliamp range, if a neon piece is not properly mounted, wired, and insulated this voltage poses both a shock and fire hazard. This is an area where cheapness does not pay off. A well constructed neon piece should be problem free for many years.
Neon can be obtained from air by fractional distillation. The first step in fractional distillation of air is to change a container of air to a liquid. The liquid air is then allowed to warm up. As the air warms, each element in air changes from a liquid back to a gas at a different temperature. The portion of air that changes back to a gas at -245.92°C is neon.
Sodium in raw water sources can vary dramatically depending on the source – lakes, rivers or wells. The naturally occurring sodium levels in lakes Huron and Erie range between 4 mg/L and 14 mg/L. The total amount of sodium in drinking water results from the amount in the source water and the sodium added from the water treatment process.
Neon was discovered by Sir William Ramsay, a Scottish chemist, and Morris M. Travers, an English chemist, shortly after their discovery of the element krypton in 1898. Like krypton, neon was discovered through the study of liquefied air.
Food products, not water, are the major dietary sources of sodium. Sodium is also found in drugs such as antacids, laxatives, aspirin and cough medicines, as well as table salt. One teaspoon of table salt contains 2300 mg of sodium. Municipal tap water at 20 mg/L has a relatively low sodium content when compared with other beverages. For example, Health Canada reports the following sodium concentrations for some common beverages:
Yes. During prolonged and strenuous exercise, both water and sodium are lost through sweating. To maintain the correct balance of water and sodium in the body, people may need not only to drink water but to ensure adequate sodium intake, whether through salty foods or specially formulated "sports drinks."
Magnesium, or rather magnesium ions are essential for every cell, every tissue, every organ and every living organism. Magnesium is indispensable for life and it has to be supplied to the body. No living organism is able to produce magnesium by itself. Without magnesium life cannot exist. Magnesium also plays a role in
Magnesium is part of the earth's crust and is absorbed from ingesting plant and animal matter or in form of magnesium salts. Certain brands of mineral water (unfortunately relatively few) are very good sources of magnesium for the human diet. According to German regulations mineral water containing only 50 mg of magnesium per liter are considered high in magnesium. From a practical point of view, however, only those brands of mineral water containing more than 100 mg of magnesium per liter should be recommended as high in magnesium.
Magnesium deficiency is caused by insufficient intake with food, reduced absorption in the intestines and early elimination through the kidneys and skin. For years many scientists have been warning that magnesium is increasingly being leached out from the soil and consequently plants will contain less and less of it. As a result, there is less magnesium present in the diet of animals – and therefore also in the human diet. The latest comprehensive study on nutrition in Germany (VERA study) showed that more than 40 percent of the population on average did not receive the recommended nutrition values of the DGE. Poor nutrition (often due to lack of awareness and insufficient knowledge) thus represents a major primary cause of magnesium deficiency.
Magnesium deficiency is definitely far more common than most doctors believe, since they are still generally being educated that magnesium deficiencies occur only very rarely. This is certainly not true. According to nutrition studies, the general assumption is that 20 to 40 percent of the population have latent magnesium deficiency.If all regulatory mechanisms are working well in a healthy body, the intestines can efficiently absorb magnesium and the kidneys can reabsorb magnesium extremely efficiently, so that the magnesium balance is nearly kept in equilibrium.
Aluminium forms a 1 nm (or sometimes slightly thicker) layer of aluminium oxide on its surface when it is exposed to air. Even though aluminium is reactive this oxide layer prevents the actual aluminium making contact with other elements which it could react with. In this way aluminium avoids reaction and corrosion. This is a particularly important feature for aluminium is its outdoor uses where being resistant to weathering is essential. If the layer breaks it immediately reforms when the aluminium is next in contact with oxygen.
Aluminium is a low density material which gives it its lightweight property. When mixed with other elements in alloys it is also very strong. This unique combination of strength and weight is essential for the transport industry. As Force = Mass x Acceleration, the bigger the mass the more force will be needed to achieve a certain acceleration. This means that using aluminium is transport vessels saves money on fuel, allows more cargo to be carried, and is better for the environment. Aluminium's corrosion resistance perfect this profile making it absolutely ideal for its uses in aeroplanes, trains, cars, and ships.
Aluminium can reflect up to 97% of light that falls upon it when highly polished, but how does it do this? Reflections occur when light hitting a material provides enough energy for an electron to move to an excited state, from where it emits a photon of light upon returning to its ground state. In aluminium there are many electrons that are free to easily become "excited" like this, this makes it an extremely good reflector.
In all materials electrons orbit atoms, and as each of the electrons has an electric charge each of these electrons produces a tiny magnetic field. In most materials electrons pair up in energy sublevels with opposite "spin" properties, so the effect of their tiny magnetic field is cancelled out by each other. However in some materials the electrons frequently don't have to pair up so an overall magnetic field can be created if a magnet forces the electrons to align in the same direction which it does in metals like iron. In iron and steel some electrons stay aligned, and this is why large magnets are often made out of these materials. In aluminium the electrons don't give an overall magnetic field in one direction, so it isn't magnetic.
Classification as a semiconductor is mostly a matter of how well you can dope it -- that is, add an impurity at a low concentration to directly and reliably affect its conductivity and band to Fermi level distances. The issue is that doping requires the donor level to be very near the band edge energy, but doping both P and N doping in diamond are a fair amount further from the band edge than the donor levels in other semiconductors.
A thin slab or slice of an inorganic material, not only limited to semiconductor grade silicon, generally prepared to a high standard.Silicon is purified metallurgically, then further purified in a special crucible. They spin the molten purified silicon and take it out on a rod anticlockwise to form a large cylindrical ingot. This is the oldest and cheapest process, spelled Czochralski technique. At the time of writing it was the 100th anniversary.
27.6% of the Earth's crust is made up of silicon. Although it is so abundant, it is not usually found in its pure state, but rather its dioxide and hydrates. SiO2SiO2 is silicon's only stable oxide, and is found in many crystalline varieties. Its purest form being quartz, but also as jasper and opal. Silicon can also be found in feldspar, micas, olivines, pyroxenes and even in water (Figure 1). In another allotropic form silicon is a brown amorphous powder most familiar in "dirty" beach sand. The crystalline form of silicon is the foundation of the semiconductor age.
Silicon and Germanium are the among the best in the center. And Silicon is better in many ways as outlined by Gautham Saravana.So that's why most are Silicon-based.
Phosphorus greatly influences the growth of algae blooms. When certain conditions are present, such as warm weather, low winds and high levels of nutrients (in specific, plant available P) in the water, algae populations can very quickly increase to form a large mass called an algae bloom. The algae bloom can cause the water to have a foul odor and pea-soup colored foam, scum or mat appearance.See the Essex Region Conservation Authority FAQ on blue green algae for more information.
Phosphorus comes from both ‘point’ sources (specific location) and ‘non point’ sources (various areas). An example of a ‘point’ source is a sewage treatment plant, while an example of a ‘non point’ source is cropland runoff due to rain. Due to water quality improvement measures undertaken from the 1960s after Lake Erie was declared ‘dead’, point sources of P were reduced significantly but not entirely eliminated. In the past few years, there has been a significant reduction in the amount of P in household dishwashing and laundry detergents in Canada. However, even today, P is still commonly found in residential lawn fertilizers, agricultural fertilizers, sewage, and industrial and commercial detergents.
The Provincial Water Quality Objective (PWQO) for phosphorus is 0.03 mg/L for streams and rivers. Through ERCA’s surface water monitoring program and a partnership with the Ministry of Environment, close to 20 water quality sites across the watershed are sampled monthly April to November each year. In 2011, the phosphorus levels ranged between 1 to 130 times the PWQO, with the highest levels in those streams discharging to Lake Erie. This includes rain event sampling results, during which the levels of P increase due to transport of P from the land into the water.
Phosphorous in the form of phosphate or phosphoric acid is often added to processed foods and soft drinks. As a result, concern has been expressed that Americans may be getting too much phosphorous. Some studies suggest that too much phosphorous can reduce the amount of calcium that the body absorbs. However, there is no scientific agreement about whether the current level of phosphorus in the American diet is harmful to the bones. For people with normal kidney function, getting more phosphorus is believed to be safe as long as they get enough calcium.
Not really. Sulphur is an element. Sulphur that is mined or recovered from oil and gas production is known as elemental sulphur, or brimstone. Sulphur can be combined with other elements to form various compounds. Sulphur compounds, such as sulphuric acid, also are produced as a by-product of ferrous and non-ferrous metal smelting. Other compounds, such as sulphur dioxide, may be emitted from petroleum products used in cars and coal generating electricity. Plants absorb sulphur from the soil as sulphate.
Well over half of the global sulphuric acid production comes from burning elemental sulphur in special equipment at points of consumption. Most of the remainder is recovered at non-ferrous metals smelters and pyrites mines. East Asia, led by China, is the largest overall acid producer, stemming largely from its rapid economic growth. It is followed by North America, Africa, and Latin America.
Most crops remove 15 to 30 kg for sulphur per hectare (S/ha). Oil crops, legumes, forages, and some vegetables require more sulphur than phosphorus for optimal yield and quality. Plants contain as much sulphur as phosphorus, with an average content of approximately 0.25%. Usual recommendations for correcting deficiency are 15 to 30 kg S/ha for cereal crops and silage grass; and 25 to 50 kg S/ha for oil crops, legume, sugarcane, and some vegetable crops. For more detailed information about sulphur demand for specific crops and regions, please see The Sulphur Institute's
Sulphur asphalt (SA), sometimes referred to as sulphur bitumen or sulphur extended asphalt (SEA), is a viable alternative for asphalt road binder, a process in which sulphur is used to extend asphalt materials as a means of energy conservation by minimizing asphalt demand. Combined with dried and heated stones and sand, either asphalt or SA can be used to make "hot mix" paving materials and build road. For more detailed information about sulphur asphalt and its use as construction materials worldwide, please see TSI's
Chlorine has a variety of uses in industry and chemistry. It can be found in processes to make paper, solvents, insecticides, paints, medicines, plastics, and textiles. It is also used to purify water supplies and pools.
Many chlorine gas exposures will improve on their own once the person is removed from the situation and able to breath clean air again. Moderate cases may need medical attention including breathing treatments similar to those given for asthma. In the most severe cases, serious airway and lung injuries can occur and patients may need to be placed on a ventilator (breathing machine) to help keep them alive while their body heals.
Chlorine bleach is “chlorine to go,” providing a convenient vehicle for delivering the germ-busting power of chlorine chemistry.Chemically speaking, chlorine bleach is a water solution of sodium hypochlorite. Common household laundry bleach, used to whiten and disinfect laundry, is typically either 5.25 percent (“regular strength”) or 6 percent sodium hypochlorite (“ultra strength”). As a surface disinfectant, chlorine bleach is approved by the U.S. Environmental Protection Agency and the U.S. Department of Agriculture for use in safe food production. It is also used to help prevent the spread of infections in homes, hospitals, nursing homes, schools and day care facilities.
Regular, unscented household bleach can be used to disinfect water. The procedure to be followed is usually written on the label. If not, find the percentage of available chlorine on the label and use the information in the following tabulation and mixing directions from U.S. EPA as a guide.
Argon is an inert, colorless and odorless element — one of the Noble gases. Used in fluorescent lights and in welding, this element gets its name from the Greek word for "lazy," an homage to how little it reacts to form compounds.
Argon isotopes are used as precursors in the production of radioisotopes. Ar-40 and Ar-38 are used in the production of radioactive K-38 which can be used as a blood flow tracer. Ar-40 is used in the production of radioactive Ar-41 which is used to trace gas flows.
Argon is the third noble gas, in period 8, and it makes up about 1% of the Earth's atmosphere. Argon has approximately the same solubility as oxygen and it is 2.5 times as soluble in water as nitrogen . This chemically inert element is colorless and odorless in both its liquid and gaseous forms.
Argon is frequently used when an inert atmosphere is needed. It is used to fill incandescent and fluorescent light bulbs to prevent oxygen from corroding the hot filament. Argon is also used to form inert atmospheres for arc welding, growing semiconductor crystals and processes that require shielding from other atmospheric gases.
Treatment for low potassium may include the use of potassium chloride supplements and increasing the amount of potassium-rich foods in the diet, such as bananas, beef or spinach. Treatment for high potassium may include the use of diuretics, kidney dialysis, or insulin injections.
Foods high in potassium include a number of fruits and vegetables, such as bananas, cantaloupe, grapefruit, oranges, tomatoes, honeydew melons, squash, and potatoes. Other foods such as legumes, nuts, and seeds are good sources of potassium too.
Potassium iodide ( KI) works only to prevent the thyroid from uptaking radioactive iodine. It is not a general radioprotective agent.
Potassium is an essential mineral that plays many biological roles. Here is a partial list of functions that potassium performs in the body:
Various foods, including vegetables, fish, and dairy, are rich in calcium. Omnivores, vegetarians, and vegans can all get enough calcium in food--though it requires some effort and attention. Supplements are also available. Here's some good information on calcium-rich foods and supplements.
Adequate vitamin D is required to absorb calcium in the intestines. Many people who live in northern climates or who don't get outdoors lack adequate vitamin D, since sunlight is necessary to metabolize it. Various foods such as fish, eggs, fortified milk and orange juice and others listed here provide vitamin D. It is a little challenging for vegans to get adequate vitamin D from food alone, but it can be done. Supplements may be necessary, especially for northerners, people who don't go out much, and people of color, who are more likely to be vitamin D deficient.
First, you can take too much. Excess calcium intake can lead to kidney stones, constipation, and other problems. Second, calcium supplements can interfere with the metabolism of certain medications and should not be taken at the same time as these. Third, some data suggests that calcium supplementation in men can cause heart disease (see above) and prostate cancer--though other studies have shown a decreased risk of cancer in those who take calcium.
Scandium is not found free in nature but is found combined in minute amounts in over 800 minerals. Rare minerals from Scandinavia and Madagascar (thortveitite, euxenite, and gadolinite) are the only known concentrated sources of the element. Commercially, scandium is obtained as a by-product of uranium refining
Scandium is used in aluminum-scandium alloys for aerospace industry components and for sports equipment such as bicycle frames, fishing rods, golf iron shafts and baseball bats. Scandium iodide is used in mercury vapor lamps, which are used to replicate sunlight in studios for the film and television industry. Scandium oxide (scandia), is used to make high intensity “stadium” lights. The radioactive isotope 45Sc is used in oil refineries as a tracing agent. Very dilute scandium sulfate is used to improve the germination of seeds such as corn, peas and wheat.
Scandium has no biological role. Only trace amounts reach the food chain, so the average person's daily intake is less than 0.1 microgram. Scadium is not toxic, although there have been suggestions that some of its compounds might be cancerogenic. Scandium is mostly dangerous in the working environment, due to the fact that damps and gasses can be inhaled with air. This can cause lung embolisms, especially during long-term exposure. Scandium can be a threat to the liver when it accumulates in the human body. Read more
Titanium is a chemical element with symbol Ti and atomic number 22. It is a lustrous transition metal with a silver color, low density and high strength. It is highly resistant to corrosion in sea water, aqua regia and chlorine.
Titanium metal has some very valuable properties. In practice, it is pretty unreactive because, like aluminium, it forms a thin protective layer of the oxide, so it doesn't corrode. Its density is 4.5 grams per cm3, much less than iron, so titanium alloys are important in the aerospace industry.
Titanium is the ninth most abundant element in the earth's crust and is primarily found in the minerals rutile (TiO2), ilmenite (FeTiO3) and sphene (CaTiSiO5). Titanium makes up about 0.57% of the earth's crust. Titanium is a strong, light metal.
Natural titanium becomes highly radioactive after being bombarded with deuterons. The emitted radiations are mostly positrons and hard gamma-rays. Natural titanium consists of five isotopes. They have atomic masses from 46 to 50 and all are stable.
Chromium is widely dispersed in the environment. In the Earth's crust chromium is present at an average of 140 parts per million (ppm), but is not distributed evenly. High concentrations of chromium can be found in certain ores, which are mined commercially.
Humans need chromium, in the form of chromium+3, for proper health. However, most people get all the daily chromium they need from a normal, well-balanced diet.
Shortly after studies showing that workplace exposure to chromium+6 increased the risk of lung cancer, researchers began to examine how chromium behaves in the human body. In experiments using cell cultures, investigators found that chromium+6 crosses cell membranes and gets into the cell much more easily than chromium+3, which does not normally get into cells. Once inside cells, chromium+6 can damage DNA, the hereditary material of the cell, and this damage can lead to mutations. Mutations in certain cancer-associated genes of the cell are believed to be the basis for initiating cancer.
Chromium is used in paints, dyes, stains, wood preservatives, curing compounds, rust inhibitors and many other products. However, the predominant use of chromium is for production of stainless steel and in chrome plating. A radioactive form of chromium is used in medicine to tag, or label, red blood cells inside the human body. The labeling is permanent for the lifetime of that cell, so it is a useful way to look at long-term patterns of blood cell turnover in the body, to look for evidence of internal bleeding and for similar studies.
Manganese dioxide (MnO2), the most common compound of manganese, makes up about 0.14% of the Earth's crust. It is used in dry cell batteries to prevent the formation of hydrogen, to remove the green color in glass that is caused by the presence of iron contaminants, and as a drying agent in black paints.
Manganese minerals are abundant on Earth, especially its oxides, silicates and carbonates. Manganese dioxide (pyrolusite) and manganese carbonate (rhodochrosite) are the most common manganese minerals.
Rich sources of manganese include whole grains, nuts, leafy vegetables, and teas. Foods high in phytic acid, such as beans, seeds, nuts, whole grains, and soy products, or foods high in oxalic acid, such as cabbage, spinach, and sweet potatoes, may slightly inhibit manganese absorption.
Iron is an essential trace element. That Means it is vital and has to be absorbed from food. It is Involved in many metabolic pathways in the body. As the central atom in hemoglobin (red blood pigment) and myoglobin, it is responsible for the transport of oxygen. Further More, it plays in important role in cellular energy supply, DNA synthesis and defense against infections.
Human beings can far more Readily use iron from foods of animal origin (heme iron) than from fruit and vegetables (non-heme iron). Iron of plant origin is normally present in a fixed bound and trivalent form (Fe 3+ ). Before it can be absorbed by the human body, it must be converted into a soluble form and reduced to bivalent iron (Fe 2+ ). Heme iron in meat, poultry and fish is present as bivalent iron. In the human organism it is absorbed Roughly two to three times more Efficiently through a specific intake path in the intestines.
Individuals with at iron storage disease and associated iron overload are particularly affected by the growing use of iron in food and food supplements. Further More, based on the current level of knowledge, men and women during the menopause are particularly at risk from the onset of chronic diseases like coronary heart disease and cancer Which are linked among other things to excessive iron intake.
Cobalt-60, a radioactive isotope of cobalt, is an important source of gamma rays and is used to treat some forms of cancer and as a medical tracer. Cobalt-60 has a half-life of 5.27 years and decays into nickel-60 through beta decay.
Cobalt is primarily used as the metal, in the preparation of magnetic, wear-resistant and high-strength alloys.
Made from the same hypoallergenic and bio-compatible alloy as the cobalt chrome used in dental and joint implants, cobalt rings are not dangerous to wear and will not cause irritation or allergic reactions. The combination of the cobalt and tungsten has long been known for its causing irritation and itching of the skin when worn in tungsten carbide rings, but without these two elements combined, there is no need for worry with cobalt chrome. And Cobalt Rings can be removed in case of any emergency just like other rings by cutting.
Nickel is found everywhere in the environment but usually only in trace amounts. For example, nickel concentrations in drinking water throughout the United States are on average 2 parts per billion (ppb) — that is, there are 2 parts nickel for every billion parts of water (2 micrograms per liter).
Nickel has been shown to be an essential trace element in several animal species and is likely to be essential in humans. However, there is no known condition in people that has been associated with nickel deficiency, and it is likely that we get all the nickel we need from its ubiquitous presence in food and water.
Like most environmental agents, the toxic effect of any metal is related to the way it gets into an organism or, in the language of toxicology, its route of exposure. Nickel has three main routes of exposure. It can be inhaled, ingested or absorbed through the skin. When nickel is inhaled, gaseous nickel compounds like nickel subsulfide or small particles of nickel dust (specifically, PM-2.5 particles — those less than 2.5 micrometers in diameter) lodge themselves deep in the lungs. In the case of inhalation exposure, scientists have found the form of nickel and its solubility is a key determining factor in the resulting toxicity mechanisms. Water-soluble nickel compounds can be absorbed by the lungs into the bloodstream and eventually removed by the kidneys. Poorly soluble nickel compounds, however, can build up in the lungs, over time and cause complications such as pulmonary fibrosis, a buildup of scar tissue in the lungs as well as bronchitis and lung cancer. The mechanism that enables nickel to cause or contribute to cancer is still very poorly understood.
Copper is naturally present in rock, either in its pure form or in compounds. Geological, meteorological, and biological processes disperse copper into the air, soil, and water as well as into organisms. The largest known copper ore deposits in the world are in Chuquicamata in the Chilean Andes, and the largest deposit of native copper is in Michigan's Upper Peninsula. The major producers of copper are Chile, which supplies 35 percent of world's copper and the United States, which produces roughly 11 percent. Canada, the countries of the former Soviet Union, Zambia, China, Poland and the Democratic Republic of the Congo are also copper-producing nations.
Copper is an essential nutrient for all living things. Copper is a component of more than 30 enzymes in the human body, including some involved in collagen synthesis. In humans copper is necessary for the healthy development of connective tissue, nerve coverings, and bone. It is also involved in both iron and energy metabolism. Copper deficiency, although rare, can cause anemia and connective tissue, bone, and nervous system abnormalities.
The answer to this question is complex. Copper is a necessary nutrient and is naturally occurring in the environment in rocks, soil, air, and water. We come into contact with copper from these sources every day but the quantity is usually tiny. Some of that copper, particularly in water, may be absorbed and used by the body. But much of the copper we come into contact with is tightly bound to other compounds rendering it neither useful nor toxic. It is important to remember that the toxicity of a substance is based on how much an organism is exposed to and the duration and route of exposure.
Zinc is extremely durable, making it a desirable surface material. Zinc is used in countertops, range hoods, roofing, flashing and artistic designs. Zinc’s timeless patina blends beautifully with other materials and makes a stunning material for many architectural designs, from traditional to contemporary.
There are few materials which are as ecologically friendly as zinc. Zinc is extremely energy efficient in its extraction and processing and is 100% recyclable without the loss of its unique physical and chemical properties, significantly reducing the need for new raw materials. In fact, over 30% of today’s supply of zinc comes from the recycling process.
The corrosion rate of an exposed rolled zinc surface is influenced by: * sulphur dioxide (SO2), typically found in very urbanised or industrialised atmospheres, * chlorides, essentially present in a marine atmosphere, * the slope and direction of the exposed surface, * surface treatments.
No, zinc is not harmful to human health or living organisms, nor is it toxic in itself since it is necessary, and indeed essential, in small quantities for all living organisms whether they are human, vegetable or animal. They draw it from their food in order to ensure that their metabolism functions properly. Zinc is essential for human health, for example for growth and for the protection of the skin. It also plays an important role in the development of the brain, foetal development, immune functions, sense of taste, sense of smell, etc.
Gallium has no known natural role in biology. Gallium(III) behaves in a similar manner to ferric salts in biological systems and has been used in some medical applications, including pharmaceuticals and radiopharmaceuticals. Gallium thermometers are manufactured as an eco-friendly alternative to mercury thermometers.
Elemental gallium is not found in nature, but it is easily obtained by smelting. Very pure gallium metal has a silvery color and its solid metal fractures conchoidally like glass. Gallium metal expands by 3.1% when it solidifies, and therefore storage in either glass or metal containers is avoided, due to the possibility of container rupture with freezing. Gallium shares the higher-density liquid state with only a few materials, like water, silicon, germanium, bismuth, and plutonium.
Gallium does not exist in free form in nature, and the few high-gallium minerals such as gallite (CuGaS2) are too rare to serve as a primary source of the element or its compounds. Its abundance in the Earth's crust is approximately 16.9 ppm. Gallium is found and extracted as a trace component in bauxite and to a small extent from sphalerite. The amount extracted from coal, diaspore and germanite in which gallium is also present is negligible. The United States Geological Survey (USGS) estimates gallium reserves to exceed 1 million tonnes, based on 50 ppm by weight concentration in known reserves of bauxite and zinc ores. Some flue dusts from burning coal have been shown to contain small quantities of gallium, typically less than 1% by weight.
"Germaine" or germanium hydride is a colorless gas GeH4 prepared by the action of lithium aluminum hydride on germanium halide in an ether solution. Germaine is a hazardous substance UN2192 which is classified as a poisonous gas (2.3). It is also a flammable gas (2.1).
While it is produced mainly from sphalerite, it is also found in silver, lead, and copper ores. Another source of germanium is fly ash of coal power plants which use coal from some coal deposits with a large concentration of germanium. Russia and China used this as a source for germanium. Russia's deposits are located in the far east of the country on Sakhalin Island. The coal mines northeast of Vladivostok have also been used as a germanium source. The deposits in China are mainly located in the lignite mines near Lincang, Yunnan; coal mines near Xilinhaote, Inner Mongolia are also used.
Inorganic germanium and organic germanium are different chemical compounds of germanium and their properties are different. Germanium is not thought to be essential to the health of plants or animals. Germanium in the environment has little or no health impact. This is primarily because it usually occurs only as a trace element in ores and carbonaceous materials, and is used in very small quantities that are not likely to be ingested, in its various industrial and electronic applications. For similar reasons, germanium in end-uses has little impact on the environment as a biohazard. Some reactive intermediate compounds of germanium are poisonous (see precautions, below).
Because it occurs naturally in the environment and as a by-product of some agricultural and industrial activities, it can enter drinking water through the ground or as runoff into surface water sources.
Human exposure to arsenic can cause both short and long term health effects. Short or acute effects can occur within hours or days of exposure. Long term exposure to arsenic hasbeen linked to the cancer of the bladder, lungs, skin, kidneys etc.
Inorganic and organic arsenic occur naturally in the environment, with inorganic forms being most abundant. Inorganic arsenic is associated with other metals in igneous and sedimentary rocks, and it also occurs in combination with many other elements, especially oxygen, chlorine, and sulfur. Organic arsenic contains carbon and hydrogen. It should be noted that inorganic and organic are not terms used to indicate pesticide usage, or even human activity, but rather the other metals and elements they are bound to.
Selenium salts are toxic in large amounts, but trace amounts are necessary for cellular function in many organisms, including all animals. Selenium is an ingredient in many multivitamins and other dietary supplements, including infant formula. It is a component of the antioxidant enzymes glutathione peroxidase and thioredoxin reductase (which indirectly reduce certain oxidized molecules in animals and some plants). It is also found in three deiodinase enzymes, which convert one thyroid hormone to another. Selenium requirements in plants differ by species, with some plants requiring relatively large amounts, and others apparently requiring none
The substance loosely called selenium sulfide (approximate formula SeS2) is the active ingredient in some anti-dandruff shampoos.[90] The selenium compound kills the scalp fungus Malassezia, which causes shedding of dry skin fragments. The ingredient is also used in body lotions to treat tinea versicolor due to infection by a different species of Malassezia fungus.
Dietary selenium comes from nuts, cereals and mushrooms. Brazil nuts are the richest ordinary dietary source (though this is soil-dependent, since the Brazil nut does not require high levels of the element for its own needs).[85][86] Recommended Dietary Allowance ~ 55 µg/day. Selenium as a dietary supplement is available in many forms, including multi-vitamins/mineral supplements - typically 20 µg/day. Selenium-specific supplements may have -200 µg/day.
Bromine has been long believed to have no essential function in mammals, but recent research suggests that bromine is necessary for tissue development. In addition, bromine is used preferentially over chlorine by one antiparasitic enzyme in the human immune system. Organobromides are needed and produced enzymatically from bromide by some lower life forms in the sea, particularly algae, and the ash of seaweed was one source of bromine's discovery. As a pharmaceutical, the simple bromide ion (Br−) has inhibitory effects on the central nervous system, and bromide salts were once a major medical sedative, before being replaced by shorter-acting drugs. They retain niche uses as antiepileptics.
Bromide compounds, especially potassium bromide, were frequently used as general sedatives in the 19th and early 20th century. Bromides in the form of simple salts are still used as anticonvulsants in both veterinary and human medicine, although the latter use varies from country to country. For example, the U.S. Food and Drug Administration (FDA) does not approve bromide for the treatment of any disease, and it was removed from over-the-counter sedative products like Bromo-Seltzer, in 1975.[39] Thus, bromide levels are not routinely measured by medical laboratories in the U.S. However, U.S. veterinary medical diagnostic testing laboratories will measure blood bromide levels on request, as an aid to treatment of epilepsy in dogs.
Long-term use of potassium bromide (or any bromide salt) can lead to bromism. This state of central nervous system depression causes the moderate toxicity of bromide in multi-gram doses for humans and other mammals. The very long half-life of bromide ion in the body (~12 days) also contributes to toxicity from bromide build-up in body fluids. Bromide ingestion may also cause a skin eruption resembling acne.
Krypton is characterized by several sharp emission lines (spectral signatures) the strongest being green and yellow. It is one of the products of uranium fission. Solid krypton is white and has a face-centered cubic crystal structure, which is a common property of all noble gases (except helium, with a hexagonal close-packed crystal structure).
Krypton is considered to be a non-toxic asphyxiant. Krypton has a narcotic potency seven times greater than air, so breathing a gas containing 50% krypton and 50% air would cause narcosis similar to breathing air at four times atmospheric pressure. This would be comparable to scuba diving at a depth of 30 m (100 ft) (see nitrogen narcosis) and potentially could affect anyone breathing it. Nevertheless, that mixture would contain only 10% oxygen and hypoxia would be a greater concern.
Krypton, like the other noble gases, can be used in lighting and photography. Krypton light has a large number of spectral lines, and krypton's high light output in plasmas allows it to play an important role in many high-powered gas lasers (krypton ion and excimer lasers), which pick out one of the many spectral lines to amplify. There is also a specific krypton fluoride laser. The high power and relative ease of operation of krypton discharge tubes caused (from 1960 to 1983) the official length of a meter to be defined in terms of the wavelength of the 605 nm (orange) spectral line of krypton-86.
Although rubidium is more abundant in Earth's crust than caesium, the limited applications and the lack of a mineral rich in rubidium limits the production of rubidium compounds to 2 to 4 tonnes per year. Several methods are available for separating potassium, rubidium, and caesium. The fractional crystallization of a rubidium and caesium alum (Cs,Rb)Al(SO4)2·12H2O yields after 30 subsequent steps pure rubidium alum. Two other methods are reported, the chlorostannate process and the ferrocyanide process
Rubidium reacts violently with water and can cause fires. To ensure safety and purity, this metal is usually kept under a dry mineral oil or sealed in glass ampoules in an inert atmosphere. Rubidium forms peroxides on exposure even to small amount of air diffusing into oil, and is thus subject to similar peroxide precautions as storage of metallic potassium.
Rubidium compounds are sometimes used in fireworks to give them a purple color. Rubidium has also been considered for use in a thermoelectric generator using the magnetohydrodynamic principle, where rubidium ions are formed by heat at high temperature and passed through a magnetic field. These conduct electricity and act like an armature of a generator thereby generating an electric current. Rubidium, particularly vaporized 87Rb, is one of the most commonly used atomic species employed for laser cooling and Bose–Einstein condensation. Its desirable features for this application include the ready availability of inexpensive diode laser light at the relevant wavelength, and the moderate temperatures required to obtain substantial vapor pressures
Yes, 89Sr is the active ingredient in Metastron (the generic version of Metastron, Generic Strontium Chloride Sr-89 Injection, its manufactured by Bio-Nucleonics Inc.), a radiopharmaceutical used for bone pain secondary to metastatic bone cancer. The strontium acts like calcium and is preferentially incorporated into bone at sites of increased osteogenesis. This localization focuses the radiation exposure on the cancerous lesion.
The human body absorbs strontium as if it were calcium. Due to the chemical similarity of the elements, the stable forms of strontium might not pose a significant health threat — in fact, the levels found naturally may actually be beneficial (see below) – but the radioactive 90Sr can lead to various bone disorders and diseases, including bone cancer. The strontium unit is used in measuring radioactivity from absorbed 90Sr.
Strontium commonly occurs in nature, the 15th most abundant element on Earth, estimated to average approximately 360 parts per million in the Earth's crust and is found chiefly as the form of the sulfate mineral celestite (SrSO4) and the carbonate strontianite (SrCO3). Of the two, celestite occurs much more frequently in sedimentary deposits of sufficient size to make development of mining facilities attractive. Because strontium is used most often in the carbonate form, strontianite would be the more useful of the two common minerals, but few deposits have been discovered that are suitable for development.
Yttrium is a soft, silver-metallic, lustrous and highly crystalline transition metal in group 3. As expected by periodic trends, it is less electronegative than its predecessor in the group, scandium, and less electronegative than the next member of period 5, zirconium; additionally, it is of comparable electronegativity to its successor in its group, lutetium, due to the lanthanide contraction. Yttrium is the first d-block element in the fifth period.
The similarities of yttrium to the lanthanides are so strong that the element has historically been grouped with them as a rare earth element,[3] and is always found in nature together with them in rare earth minerals.[11] Chemically, yttrium resembles these elements more closely than its neighbor in the periodic table, scandium,[12] and if its physical properties were plotted against atomic number then it would have an apparent number of 64.5 to 67.5, placing it between the lanthanides gadolinium and erbium.
Yttrium was used in the yttrium barium copper oxide (YBa2Cu3O7, aka 'YBCO' or '1-2-3') superconductor developed at the University of Alabama and the University of Houston in 1987. This superconductor operated at 93 K, notable because this is above liquid nitrogen's boiling point (77.1 K). As the price of liquid nitrogen is lower than that of liquid helium, which must be used for the metallic superconductors, the operating costs would decrease.
Zirconium is mainly used as a refractory and opacifier, although it is used in small amounts as an alloying agent for its strong resistance to corrosion. Zirconium forms a variety of inorganic and organometallic compounds such as zirconium dioxide and zirconocene dichloride, respectively. Five isotopes occur naturally, three of which are stable. Zirconium compounds have no known biological role.
Cladding for nuclear reactor fuels consumes about 1% of the zirconium supply. For this purpose, it is mainly used in the form of zircaloys. The benefits of Zr alloys is their low neutron-capture cross-section and good resistance to corrosion under normal service conditions. The development of efficient methods for the separation of zirconium from hafnium was required for this application.
Although zirconium has no known biological role, the human body contains, on average, 250 milligrams of zirconium, and daily intake is approximately 4.15 milligrams (3.5 milligrams from food and 0.65 milligrams from water), depending on dietary habits.Zirconium is widely distributed in nature and is found in all biological systems, for example: 2.86 μg/g in whole wheat, 3.09 μg/g in brown rice, 0.55 μg/g in spinach, 1.23 μg/g in eggs, and 0.86 μg/g in ground beef. Further, zirconium is commonly used in commercial products (e.g. deodorant sticks, aerosol antiperspirants) and also in water purification (e.g. control of phosphorus pollution, bacteria- and pyrogen-contaminated water).
Niobium is used mostly in alloys, the largest part in special steel such as that used in gas pipelines. Although these alloys contain a maximum of 0.1%, the small percentage of niobium enhances the strength of the steel. The temperature stability of niobium-containing superalloys is important for its use in jet and rocket engines. Niobium is used in various superconducting materials. These superconducting alloys, also containing titanium and tin, are widely used in the superconducting magnets of MRI scanners
Niobium is an effective microalloying element for steel. Adding niobium to the steel causes the formation of niobium carbide and niobium nitride within the structure of the steel. These compounds improve the grain refining, retardation of recrystallization, and precipitation hardening of the steel. These effects in turn increase the toughness, strength, formability, and weldability of the microalloyed steel. Microalloyed stainless steels have a niobium content of less than 0.1%. It is an important alloy addition to high strength low alloy steels which are widely used as structural components in modern automobiles. These niobium-containing alloys are strong and are often used in pipeline construction.
Niobium has no known biological role. While niobium dust is an eye and skin irritant and a potential fire hazard, elemental niobium on a larger scale is physiologically inert (and thus hypoallergenic) and harmless. It is frequently used in jewelry and has been tested for use in some medical implants. Niobium-containing compounds are rarely encountered by most people, but some are toxic and should be treated with care. The short-and long-term exposure to niobates and niobium chloride, two chemicals that are water-soluble, have been tested in rats. Rats treated with a single injection of niobium pentachloride or niobates show a median lethal dose (LD50) between 10 and 100 mg/kg. For oral administration the toxicity is lower; a study with rats yielded a LD50 after seven days of 940 mg/kg.
Molybdenum works its way into your diet through plants, which take it up from the soil. It forms a crucial part of a little enzyme called sulfite oxidase. The enzyme breaks down incoming sulfites and turns them into useful food. Take away molybdenum, and the enzyme, and things get nasty. The lowest-level problem you can look forward to is a severe allergic reaction. Continued molybdenum deprivation causes uric acid to build up in the blood, which brings on horribly inflammed and painful joints. At it worst, molybdenum deficiency takes out the nervous system.
It’s possible. The FDA made it illegal to add sulfites to raw fruits and vegetables, but pretty much every other food has some sulfites in it. Preserved fruits, restaurant food (especially shellfish and potatoes), and almost anything you find on the shelf in the grocery store. Beer and wine both naturally contain sulfites. Basically, not enough molybdenum in your system makes it so nearly all your food will kill you.
About 86% of molybdenum produced is used in metallurgical applications such as alloys, with the rest of molybdenum used as compounds in chemical applications. Estimated fractional global industrial use of molybdenum is structural steel 35%, stainless steel 25%, chemicals 14%, tool & high-speed steels 9%, cast iron 6%, molybdenum elemental metal 6%, and superalloys, 5%. The ability of molybdenum to withstand extreme temperatures without significantly expanding or softening makes it useful in applications that involve intense heat, including the manufacture of armor, aircraft parts, electrical contacts, industrial motors and filaments.
The long half-life of technetium-99 and its ability to form an anionic species makes it a major concern for long-term disposal of radioactive waste. Many of the processes designed to remove fission products in reprocessing plants aim at cationic species like caesium (e.g., caesium-137) and strontium (e.g., strontium-90). Hence the pertechnetate is able to escape through these treatment processes. Current disposal options favor burial in continental, geologically stable rock. The primary danger with such a course is that the waste is likely to come into contact with water, which could leach radioactive contamination into the environment. The anionic pertechnetate and iodide do not adsorb well onto the surfaces of minerals, so they are likely to be washed away. By comparison plutonium, uranium, and caesium are much more able to bind to soil particles. Technetium could also be immobilized by some environments, such as lake bottom sediments, due to microbial activity; for this reason, the environmental chemistry of technetium is an active area of research.
The feasibility of technetium-99m production with the 22-MeV-proton bombardment of a molybdenum-100 target in medical cyclotrons following the reaction 100Mo(p,2n)99mTc was demonstrated in 1971. The recent shortages of medical technetium-99m reignited the interest in its production by proton bombardment of isotopically-enriched (>99.5%) molybdenum-100 targets. Other particle accelerator-based isotope production techniques have been investigated to obtain molybdenum-99 from molybdenum-100 via (n,2n) or (γ,n) reactions.
Technetium-99m ("m" indicates that this is a metastable nuclear isomer) is used in radioactive isotope medical tests, for example as the radioactive part of a radioactive tracer that medical equipment can detect in the human body. It is well suited to the role because it emits readily detectable 140 keV gamma rays, and its half-life is 6.01 hours (meaning that about 94% of it decays to technetium-99 in 24 hours). The chemistry of technetium allows it to be bound to a variety of non-radioactive compounds. It is the entire compound that determines how it is metabolized. Therefore a single radioactive isotope can be used for a multitude of diagnostic tests. There are more than 50 commonly used radiopharmaceuticals based on technetium-99m for imaging and functional studies of the brain, myocardium, thyroid, lungs, liver, gallbladder, kidneys, skeleton, blood, and tumors.
Roughly 12 tonnes of ruthenium is mined each year with world reserves estimated as 5,000 tonnes. The composition of the mined platinum group metal (PGM) mixtures varies in a wide range depending on the geochemical formation. For example, the PGMs mined in South Africa contain on average 11% ruthenium while the PGMs mined in the former USSR contain only 2% based on research dating from 1992.
Chemical vapor deposition of ruthenium is used as a method to produce thin films of pure ruthenium on substrates. These films show promising properties for the use in microchips and for the giant magnetoresistive read element for hard disk drives.[54] Ruthenium was also suggested as a possible material for microelectronics because its use is compatible with semiconductor processing techniques.
Ruthenium is a versatile catalyst. Hydrogen sulfide can be split by light by using an aqueous suspension of CdS particles loaded with ruthenium dioxide. This may be useful in the removal of H2S in oil refineries and other industrial processing facilities.[51] Organometallic ruthenium carbene and alkylidene complexes have been found to be highly efficient catalysts for olefin metathesis, a process with important applications in organic and pharmaceutical chemistry.[52] Ruthenium-promoted cobalt catalysts are used in Fischer-Tropsch synthesis.
Roughly 12 tonnes of ruthenium is mined each year with world reserves estimated as 5,000 tonnes. The composition of the mined platinum group metal (PGM) mixtures varies in a wide range depending on the geochemical formation. For example, the PGMs mined in South Africa contain on average 11% ruthenium while the PGMs mined in the former USSR contain only 2% based on research dating from 1992.
Rhodium is a fission product of uranium-235; therefore, each kilogram of fission products contains significant amounts of the lighter platinum group metals including rhodium. Used nuclear fuel might be a possible source for rhodium. However, the extraction is complex and expensive, and the also present radioactive isotopes of rhodium would require a storage for several half-lives of the longest-lived decaying isotope (i.e. about 10 years) to reduce the radioactivity. This makes this source of rhodium unattractive and no large-scale extraction has been attempted
Being a noble metal, pure rhodium is inert. However, chemical complexes of rhodium can be reactive. Median lethal dose (LD50) for rats is 198 mg of rhodium chloride (RhCl3) per kilogram of body weight.[42] Like the other noble metals, all of which are too inert to occur as chemical compounds in nature, rhodium has not been found to play any biological role. If used in elemental form rather than as compounds, the metal is harmless.
Over half of the supply of palladium and its congener platinum goes into catalytic converters, which convert up to 90% of harmful gases from auto exhaust (hydrocarbons, carbon monoxide, and nitrogen dioxide) into less-harmful substances (nitrogen, carbon dioxide and water vapor). Palladium is also used in electronics, dentistry, medicine, hydrogen purification, chemical applications, groundwater treatment and jewelry. Palladium plays a key role in the technology used for fuel cells, which combine hydrogen and oxygen to produce electricity, heat, and water.
Palladium is a metal with low toxicity. It is poorly absorbed by human body when digested. Plants such as the water hyacinth are killed by low levels of palladium salts. Most other plants tolerate it, although tests show that at levels above 0.0003% growth is affected. High doses of palladium could be poisonous; tests on rodents suggest it may be carcinogenic, but there is no clear evidence that the element has any adverse effects on humans.
The second-biggest application of palladium in electronics is in the manufacture of multilayer ceramic capacitors, in which palladium (and palladium-silver alloys) are used as electrodes. Palladium (sometimes alloyed with nickel) is used in connector platings in consumer electronics. It is also used in plating of electronic components and in soldering materials. The electronic sector consumed 1.07 million troy ounces (33.2 tonnes) of palladium in 2006, according to a Johnson Matthey report.
Unlike other "essential" elements such as calcium, human bodies don't need silver to function. Though silver was once used in medical applications, modern substitutes have largely superceded these uses, and there would be no ill health effects from going through life without ever contacting silver.
Silver is the reflective coating of choice for concentrated solar power reflectors. In 2009, scientists at the National Renewable Energy Laboratory (NREL) and SkyFuel teamed to develop large curved sheets of metal that have the potential to be 30% less expensive than today's best collectors of concentrated solar power by replacing glass-based models with a silver polymer sheet that has the same performance as the heavy glass mirrors, but at much lower cost and weight. It also is much easier to deploy and install. The glossy film uses several layers of polymers, with an inner layer of pure silver.
The medical uses of silver include its incorporation into wound dressings, and its use as an antibiotic coating in medical devices. Wound dressings containing silver sulfadiazine or silver nanomaterials may be used to treat external infections. Silver is also used in some medical applications, such as urinary catheters and endotracheal breathing tubes, where there is tentative evidence that it is effective in reducing catheter-related urinary tract infections and ventilator-associated pneumonia respectively. The silver ion (Ag+) is bioactive and in sufficient concentration readily kills bacteria in vitro. Silver and silver nanoparticles are used as an antimicrobial in a variety of industrial, healthcare and domestic applications.
Cadmium is a soft, malleable, ductile, bluish-white divalent metal. It is similar in many respects to zinc but forms complex compounds. Unlike most other metals, cadmium is resistant to corrosion and as a result it is used as a protective layer when deposited on other metals. As a bulk metal, cadmium is insoluble in water and is not flammable; however, in its powdered form it may burn and release toxic fumes.
In 2009, 86% of cadmium was used in batteries, predominantly in rechargeable nickel-cadmium batteries. Nickel-cadmium cells have a nominal cell potential of 1.2 V. The cell consists of a positive nickel hydroxide electrode and a negative cadmium electrode plate separated by an alkaline electrolyte (potassium hydroxide). The European Union set the allowed use of cadmium in electronics in 2004 to limits of 0.01%,[35] with several exceptions, but reduced the allowed content of cadmium in batteries to 0.002%.
Cadmium has no known useful role in higher organisms, but a cadmium-dependent carbonic anhydrase has been found in some marine diatoms. The diatoms live in environments with very low zinc concentrations and cadmium performs the function normally carried out by zinc in other anhydrases. The discovery was made using X-ray absorption fluorescence spectroscopy (XAFS). The highest concentration of cadmium has been found to be absorbed in the kidneys of humans, and up to about 30 mg of cadmium is commonly inhaled throughout childhood and adolescence. Cadmium can be used to block calcium channels in chicken neurons.Analytical methods for the determination of cadmium in biological samples have been reviewed.
Indium has no metabolic role in any organism. In a similar way to aluminium salts, indium(III) ions can be toxic to the kidney when given by injection, but oral indium compounds do not have the chronic toxicity of salts of heavy metals, probably due to poor absorption in basic conditions. Radioactive indium-111 (in very small amounts on a chemical basis) is used in nuclear medicine tests, as a radiotracer to follow the movement of labeled proteins and white blood cells in the body.
Indium is created via the long-lasting, (up to thousands of years), s-process in low-to-medium mass stars (which range in mass between 0.6 and 10 solar masses). When a silver-109 atom (the isotope of which approximately half of all silver in existence is composed), catches a neutron, it undergoes a beta decay to become cadmium-110. Capturing further neutrons, it becomes cadmium-115, which decays to indium-115 via another beta decay. This explains why the radioactive isotope predominates in abundance compared to the stable one.
The health effects of exposure to Indium have been little studied. The EU does not consider it a chemical of "high concern". Indium tin oxide and indium phosphide have been shown to cause harm to the pulmonary and immune systems, predominantly through ionic indium. Mild eye irritation may result from exposure to its dust or vapor. Lab studies in animals have shown injection may cause liver and kidney damage. Because of its rarity, little is known about its ecological fate, and bioaccumulation has not been ruled out.
Tin is produced by carbothermic reduction of the oxide ore with carbon or coke. Both reverberatory furnace and electric furnace can be used.
The major commercial application of organotin compounds is in the stabilization of PVC plastics. In the absence of such stabilizers, PVC would otherwise rapidly degrade under heat, light, and atmospheric oxygen, to give discolored, brittle products. Tin scavenges labile chloride ions (Cl−), which would otherwise initiate loss of HCl from the plastic material.[72] Typical tin compounds are carboxylic acid derivatives of dibutyltin dichloride, such as the dilaurate.
Cases of poisoning from tin metal, its oxides, and its salts are "almost unknown". On the other hand, certain organotin compounds are almost as toxic as cyanide. People can be exposed to tin in the workplace by breathing it in, skin contact, and eye contact. The Occupational Safety and Health Administration (OSHA) has set the legal limit (Permissible exposure limit) for tin exposure in the workplace as 2 mg/m3 over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 2 mg/m3 over an 8-hour workday. At levels of 100 mg/m3, tin is immediately dangerous to life and health.
Antimony is in the nitrogen group (group 15) and has an electronegativity of 2.05. As expected from periodic trends, it is more electronegative than tin or bismuth, and less electronegative than tellurium or arsenic. Antimony is stable in air at room temperature, but reacts with oxygen if heated, to form antimony trioxide, Sb2O3. Antimony is a silvery, lustrous gray metal that has a Mohs scale hardness of 3. Thus pure antimony is too soft to make hard objects; coins made of antimony were issued in China's Guizhou province in 1931, but because of their rapid wear, their minting was discontinued. Antimony is resistant to attack by acids.
The major commercial application of organotin compounds is in the stabilization of PVC plastics. In the absence of such stabilizers, PVC would otherwise rapidly degrade under heat, light, and atmospheric oxygen, to give discolored, brittle products. Tin scavenges labile chloride ions (Cl−), which would otherwise initiate loss of HCl from the plastic material. Typical tin compounds are carboxylic acid derivatives of dibutyltin dichloride, such as the dilaurate.
The effects of antimony and its compounds on human and environmental health differ widely. The massive antimony metal does not affect human and environmental health. Inhalation of antimony trioxide (and similar poorly soluble Sb(III) dust particles such as antimony dust) is considered harmful and suspected of causing cancer. However, these effects are only observed with female rats and after long-term exposure to high dust concentrations. The effects are hypothesized to be attributed to inhalation of poorly soluble Sb particles leading to impaired lung clearance, lung overload, inflammation and ultimately tumour formation, not to exposure to antimony ions (OECD, 2008). Antimony chlorides are corrosive to skin. The effects of antimony are not comparable to arsenic; this might be caused by the significant differences of uptake, metabolism and excretion between arsenic and antimony.
Tellurium has no biological function, although fungi can incorporate it in place of sulfur and selenium into amino acids such as tellurocysteine and telluromethionine. In humans, tellurium is partly metabolized into dimethyl telluride, (CH3)2Te, a gas with a garlic-like odor which is exhaled in the breath of victims of tellurium toxicity or exposure.
The largest consumer of tellurium is metallurgy, where it is used in iron, copper and lead alloys. When added to stainless steel and copper it makes these metals more machinable. It is alloyed into cast iron for promoting chill for spectroscopic purposes, as the presence of electrically conductive free graphite tends to deleteriously affect spark emission testing results. In lead it improves strength and durability and decreases the corrosive action of sulfuric acid.
Tellurium and tellurium compounds are considered to be mildly toxic and need to be handled with care, although acute poisoning is rare. Tellurium poisoning is particularly difficult to treat as many chelation agents used in the treatment of metal toxicities will increase the toxicity of tellurium. Tellurium is not reported to be carcinogenic. Humans exposed to as little as 0.01 mg/m3 or less in air exude a foul garlic-like odor known as "tellurium breath." This is caused from the tellurium being metabolized by the body, converting it from any oxidation state to dimethyl telluride, (CH3)2Te. This is a volatile compound with a highly pungent garlic-like smell. Even though the metabolic pathways of tellurium are not known, it is generally assumed that they resemble those of the more extensively studied selenium, because the final methylated metabolic products of the two elements are similar.
Iodine is an element that is needed for the production of thyroid hormone. The body does not make iodine, so it is an essential part of your diet. Iodine is found in various foods (see Table 1). If you do not have enough iodine in your body, you cannot make enough thyroid hormone.
Elemental iodine (I2) is toxic if taken orally. The lethal dose for an adult human is 30 mg/kg, which is about 2.1–2.4 grams for a human weighing 70 to 80 kg (even if experiments on rats demonstrated that these animals could survive after eating a 14000 mg/kg dose). Excess iodine can be more cytotoxic in the presence of selenium deficiency. Iodine supplementation in selenium-deficient populations is, in theory, problematic, partly for this reason Its toxicity derives from its oxidizing properties, which make it able to denaturate proteins (including enzymes).
Some people develop a hypersensitivity to iodine-containing products and foods. Applications of tincture of iodine or Betadine can cause rashes, sometimes severe. Parenteral use of iodine-based contrast agents (see above) can cause reactions ranging from a mild rash to fatal anaphylaxis. Such reactions have led to the misconception (widely held, even among physicians) that some people are allergic to iodine itself; even allergies to iodine-rich seafood have been so construed. In fact, there has never been a confirmed report of a true iodine allergy, and an allergy to elemental iodine or simple iodide salts is theoretically impossible. Hypersensitivity reactions to iodine-containing products and foods are apparently related to their other molecular components; thus, a person who has demonstrated an allergy to one iodine-containing food or product should not be assumed to have an allergy to another one. Patients with various food allergies (shellfish, egg, milk, etc.) as well as asthma are more likely to suffer reactions to iodine-containing contrast media; so as with all medications, the potential severity of reactions to medical iodine-containing products should prompt questions about a patient's allergy history before they are administered
In 1962, a group of researchers at Bell Laboratories discovered laser action in xenon, and later found that the laser gain was improved by adding helium to the lasing medium. The first excimer laser used a xenon dimer (Xe2) energized by a beam of electrons to produce stimulated emission at an ultraviolet wavelength of 176 nm. Xenon chloride and xenon fluoride have also been used in excimer (or, more accurately, exciplex) lasers. The xenon chloride excimer laser has been employed, for example, in certain dermatological uses.
Gamma emission from the radioisotope 133Xe of xenon can be used to image the heart, lungs, and brain, for example, by means of single photon emission computed tomography. 133Xe has also been used to measure blood flow. Xenon, particularly hyperpolarized 129Xe, is a useful contrast agent for magnetic resonance imaging (MRI). In the gas phase, it can be used to image empty space such as cavities in a porous sample or alveoli in lungs. Hyperpolarization renders 129Xe much more detectable via magnetic resonance imaging and has been used for studies of the lungs and other tissues. It can be used, for example, to trace the flow of gases within the lungs. Because xenon is soluble in water and also in hydrophobic solvents, it can be used to image various soft living tissues.
Many oxygen-containing xenon compounds are toxic due to their strong oxidative properties, and explosive due to their tendency to break down into elemental xenon plus diatomic oxygen (O2), which contains much stronger chemical bonds than the xenon compounds. Xenon gas can be safely kept in normal sealed glass or metal containers at standard temperature and pressure. However, it readily dissolves in most plastics and rubber, and will gradually escape from a container sealed with such materials.[180] Xenon is non-toxic, although it does dissolve in blood and belongs to a select group of substances that penetrate the blood–brain barrier, causing mild to full surgical anesthesia when inhaled in high concentrations with oxygen.
Caesium is a very soft (it has the lowest hardness of all elements, 0.2 Mohs), very ductile, pale metal, which darkens in the presence of trace amounts of oxygen. It has a melting point of 28.4 °C (83.1 °F), making it one of the few elemental metals that are liquid near room temperature. Mercury is the only elemental metal with a known melting point lower than caesium. In addition, the metal has a rather low boiling point, 641 °C (1,186 °F), the lowest of all metals other than mercury. Its compounds burn with a blue or violet colour.
Caesium-based atomic clocks observe electromagnetic transitions in the hyperfine structure of caesium-133 atoms and use it as a reference point. The first accurate caesium clock was built by Louis Essen in 1955 at the National Physical Laboratory in the UK. They have been improved repeatedly over the past half-century, and form the basis for standards-compliant time and frequency measurements, and have been regarded as "the most accurate realization of a unit that mankind has yet achieved." These clocks measure frequency with an error of 2 to 3 parts in 1014, which would correspond to a time measurement accuracy of 2 nanoseconds per day, or one second in 1.4 million years. The latest versions are accurate to better than 1 part in 1015, which means they would be off by about 1 second in 20 million years,. Caesium clocks are also used in networks that oversee the timing of cell phone transmissions and the information flow on the Internet.
Nonradioactive caesium compounds are only mildly toxic. Exposure to large amounts can cause hyperirritability and spasms, due to the chemical similarity of caesium to potassium, but such amounts would not ordinarily be encountered in natural sources and nonradioactive caesium is not a significant environmental hazard. The median lethal dose (LD50) value for caesium chloride in mice is 2.3 g per kilogram, which is comparable to the LD50 values of potassium chloride and sodium chloride. The principal use of nonradioactive caesium, as caesium formate in petroleum drilling fluids, takes advantage of its low toxicity compared to less costly alternatives.
Barium, as a metal or when alloyed with aluminium, is used to remove unwanted gases (gettering) from vacuum tubes, such as TV picture tubes. Barium is suitable for this purpose because of its low vapor pressure and reactivity towards oxygen, nitrogen, carbon dioxide, and water; it can even partly remove noble gases by dissolving them in the crystal lattice. This application is gradually disappearing due to the rising popularity of the tubeless LCD and plasma sets.
A barium-containing mineral benitoite (barium titanium silicate) occurs as a very rare blue fluorescent gemstone, and is the official state gem of California.
Because of the high reactivity of the metal, toxicological data are available only for compounds. Water-soluble barium compounds are poisonous. At low doses, barium ions act as a muscle stimulant, whereas higher doses affect the nervous system, causing cardiac irregularities, tremors, weakness, anxiety, dyspnea and paralysis. This may be due to the ability of Ba2+ to block potassium ion channels, which are critical to the proper function of the nervous system. Other target organs for water-soluble barium compounds (i.e., barium ions) are eyes, immune system, heart, respiratory system, and skin. They affect the body strongly, causing, for example, blindness and sensitization.
Zirconium is a good nuclear fuel-rod cladding metal, with the desirable properties of a very low neutron capture cross-section and good chemical stability at high temperatures. However, because of hafnium's neutron-absorbing properties, hafnium impurities in zirconium would cause it to be far less useful for nuclear-reactor applications. Thus, a nearly complete separation of zirconium and hafnium is necessary for their use in nuclear power. The production of hafnium-free zirconium is the main source for hafnium.
Hafnium is used in alloys with iron, titanium, niobium, tantalum, and other metals. An alloy used for liquid rocket thruster nozzles, for example the main engine of the Apollo Lunar Modules, is C103 which consists of 89% niobium, 10% hafnium and 1% titanium. Small additions of hafnium increase the adherence of protective oxide scales on nickel-based alloys. It improves thereby the corrosion resistance especially under cyclic temperature conditions that tend to break oxide scales by inducing thermal stresses between the bulk material and the oxide layer.
Care needs to be taken when machining hafnium because it is pyrophoric—fine particles can spontaneously combust when exposed to air. Compounds that contain this metal are rarely encountered by most people. The pure metal is not considered toxic, but hafnium compounds should be handled as if they were toxic because the ionic forms of metals are normally at greatest risk for toxicity, and limited animal testing has been done for hafnium compounds.
Zirconium is a good nuclear fuel-rod cladding metal, with the desirable properties of a very low neutron capture cross-section and good chemical stability at high temperatures. However, because of hafnium's neutron-absorbing properties, hafnium impurities in zirconium would cause it to be far less useful for nuclear-reactor applications. Thus, a nearly complete separation of zirconium and hafnium is necessary for their use in nuclear power. The production of hafnium-free zirconium is the main source for hafnium.
Tantalum is considered a conflict resource. Coltan, the industrial name for a columbite–tantalite mineral from which columbium (i.e. niobium) and tantalum are extracted, can also be found in Central Africa, which is why tantalum is being linked to warfare in the Democratic Republic of the Congo (formerly Zaire). According to an October 23, 2003 United Nations report, the smuggling and exportation of coltan has helped fuel the war in the Congo, a crisis that has resulted in approximately 5.4 million deaths since 1998 – making it the world’s deadliest documented conflict since World War II. Ethical questions have been raised about responsible corporate behavior, human rights, and endangering wildlife, due to the exploitation of resources such as coltan in the armed conflict regions of the Congo Basin. However, although important for the local economy in Congo, the contribution of coltan mining in Congo to the world supply of tantalum is usually small. The United States Geological Survey reports in its yearbook that this region produced a little less than 1% of the world's tantalum output in 2002–2006, peaking at 10% in 2000 and 2008.
Compounds containing tantalum are rarely encountered in the laboratory. The metal is highly biocompatible and is used for body implants and coatings, therefore attention may be focused on other elements or the physical nature of the chemical compound People can be exposed to tantalum in the workplace by breathing it in, skin contact, or eye contact. The Occupational Safety and Health Administration (OSHA) has set the legal limit (permissible exposure limit) for tantalum exposure in the workplace as 5 mg/m3 over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 5 mg/m3 over an 8-hour workday and a short-term limit of 10 mg/m3. At levels of 2500 mg/m3, tantalum is immediately dangerous to life and health.
The hardness and density of tungsten are applied in obtaining heavy metal alloys. A good example is high speed steel, which can contain as much as 18% tungsten. Tungsten's high melting point makes tungsten a good material for applications like rocket nozzles, for example in the UGM-27 Polaris submarine-launched ballistic missile. Tungsten alloys are used in a wide range of different applications, including the aerospace and automotive industries and radiation shielding. Superalloys containing tungsten, such as Hastelloy and Stellite, are used in turbine blades and wear-resistant parts and coatings.
Tungsten, usually alloyed with nickel and iron or cobalt to form heavy alloys, is used in kinetic energy penetrators as an alternative to depleted uranium, in applications where uranium's radioactivity is problematic even in depleted form, or where uranium's additional pyrophoric properties are not required (for example, in ordinary small arms bullets designed to penetrate body armor). Similarly, tungsten alloys have also been used in cannon shells, grenades and missiles, to create supersonic shrapnel. Tungsten has also been used in Dense Inert Metal Explosives, which use it as dense powder to reduce collateral damage while increasing the lethality of explosives within a small radius.
Because tungsten is rare and its compounds are generally inert, the effects of tungsten on the environment are limited. The median lethal dose LD50 depends strongly on the animal and the method of administration and varies between 59 mg/kg (intravenous, rabbits) and 5000 mg/kg (tungsten metal powder, intraperitoneal, rats). People can be exposed to tungsten in the workplace by breathing it in, swallowing it, skin contact, and eye contact. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 5 mg/m3 over an 8-hour workday and a short term limit of 10 mg/m3.
Rhenium is one of the rarest elements in Earth's crust with an average concentration of 1 ppb; other sources quote the number of 0.5 ppb making it the 77th most abundant element in Earth's crust. Rhenium is probably not found free in nature (its possible natural occurrence is uncertain), but occurs in amounts up to 0.2% in the mineral molybdenite (which is primarily molybdenum disulfide), the major commercial source, although single molybdenite samples with up to 1.88% have been found. Chile has the world's largest rhenium reserves, part of the copper ore deposits, and was the leading producer as of 2005.
The nickel-based superalloys have improved creep strength with the addition of rhenium. The alloys normally contain 3% or 6% of rhenium. Second-generation alloys contain 3%; these alloys were used in the engines for the F-15 and F-16, whereas the newer single-crystal third-generation alloys contain 6% of rhenium; they are used in the F-22 and F-35 engines. Rhenium is also used in the superalloys, such as CMSX-4 (2nd gen) and CMSX-10 (3rd gen) that are used in industrial gas turbine engines like the GE 7FA. Rhenium can cause superalloys to become microstructurally unstable, forming undesirable TCP (topologically close packed) phases. In 4th- and 5th-generation superalloys, ruthenium is used to avoid this effect.
Very little is known about the toxicity of rhenium and its compounds because they are used in very small amounts. Soluble salts, such as the rhenium halides or perrhenates, could be hazardous due to elements other than rhenium or due to rhenium itself.Only a few compounds of rhenium have been tested for their acute toxicity; two examples are potassium perrhenate and rhenium trichloride, which were injected as a solution into rats. The perrhenate had an LD50 value of 2800 mg/kg after seven days (this is very low toxicity, similar to that of table salt) and the rhenium trichloride showed LD50 of 280 mg/kg.
Osmium is obtained commercially as a by-product from nickel and copper mining and processing. During electrorefining of copper and nickel, noble metals such as silver, gold and the platinum group metals, together with non-metallic elements such as selenium and tellurium settle to the bottom of the cell as anode mud, which forms the starting material for their extraction. In order to separate the metals, they must first be brought into solution.
Because of the volatility and extreme toxicity of its oxide, osmium is rarely used in its pure state, and is instead often alloyed with other metals. Those alloys are utilized in high-wear applications. Osmium alloys such as osmiridium are very hard and, along with other platinum group metals, are used in the tips of fountain pens, instrument pivots, and electrical contacts, as they can resist wear from frequent operation. They were also used for the tips of phonograph styli during the late 78 rpm and early "LP" and "45" record era, circa 1945 to 1955. Although very durable compared to steel and chromium needle points, osmium alloy tips wore out far more rapidly than competing but costlier sapphire and diamond tips and were discontinued.
Finely divided metallic osmium is pyrophoric and reacts with oxygen at room temperature forming volatile osmium tetroxide. Some osmium compounds are also converted to the tetroxide if oxygen is present. This makes osmium tetroxide the main source of contact with the environment. Osmium tetroxide is highly volatile and penetrates skin readily, and is very toxic by inhalation, ingestion, and skin contact. Airborne low concentrations of osmium tetroxide vapor can cause lung congestion and skin or eye damage, and should therefore be used in a fume hood. Osmium tetroxide is rapidly reduced to relatively inert compounds by polyunsaturated vegetable oils, such as corn oil.
The Cretaceous–Paleogene boundary of 66 million years ago, marking the temporal border between the Cretaceous and Paleogene periods of geological time, was identified by a thin stratum of iridium-rich clay. A team led by Luis Alvarez proposed in 1980 an extraterrestrial origin for this iridium, attributing it to an asteroid or comet impact. Their theory, known as the Alvarez hypothesis, is now widely accepted to explain the extinction of the non-avian dinosaurs. A large buried impact crater structure with an estimated age of about 66 million years was later identified under what is now the Yucatán Peninsula (the Chicxulub crater).Dewey M. McLean and others argue that the iridium may have been of volcanic origin instead, because Earth's core is rich in iridium, and active volcanoes such as Piton de la Fournaise, in the island of Réunion, are still releasing iridium.
The high melting point, hardness and corrosion resistance of iridium and its alloys determine most of its applications. Iridium and especially iridium–platinum alloys or osmium–iridium alloys have a low wear and are used, for example, for multi-pored spinnerets, through which a plastic polymer melt is extruded to form fibers, such as rayon. Osmium–iridium is used for compass bearings and for balances. Their resistance to arc erosion makes iridium alloys ideal for electrical contacts for spark plugs, and iridium-based spark plugs are particularly used in aviation.
Iridium in bulk metallic form is not biologically important or hazardous to health due to its lack of reactivity with tissues; there are only about 20 parts per trillion of iridium in human tissue.[12] Like most metals, finely divided iridium powder can be hazardous to handle, as it is an irritant and may ignite in air.[44] Very little is known about the toxicity of iridium compounds because they are used in very small amounts, but soluble salts, such as the iridium halides, could be hazardous due to elements other than iridium or due to iridium itself. However, most iridium compounds are insoluble, which makes absorption into the body difficult.
The Cretaceous–Paleogene boundary of 66 million years ago, marking the temporal border between the Cretaceous and Paleogene periods of geological time, was identified by a thin stratum of iridium-rich clay. A team led by Luis Alvarez proposed in 1980 an extraterrestrial origin for this iridium, attributing it to an asteroid or comet impact. Their theory, known as the Alvarez hypothesis, is now widely accepted to explain the extinction of the non-avian dinosaurs. A large buried impact crater structure with an estimated age of about 66 million years was later identified under what is now the Yucatán Peninsula (the Chicxulub crater).Dewey M. McLean and others argue that the iridium may have been of volcanic origin instead, because Earth's core is rich in iridium, and active volcanoes such as Piton de la Fournaise, in the island of Réunion, are still releasing iridium.
Platinum's rarity as a metal has caused advertisers to associate it with exclusivity and wealth. "Platinum" debit and credit cards have greater privileges than "gold" cards. "Platinum awards" are the second highest possible, ranking above "gold", "silver" and "bronze", but below diamond. For example, in the United States, a musical album that has sold more than 1 million copies, will be credited as "platinum", whereas an album that sold more than 10 million copies will be certified as "diamond". Some products, such as blenders and vehicles, with a silvery-white color are identified as "platinum".
According to the Centers for Disease Control and Prevention, short-term exposure to platinum salts may cause irritation of the eyes, nose, and throat, and long-term exposure may cause both respiratory and skin allergies. The current OSHA standard is 2 micrograms per cubic meter of air averaged over an 8-hour work shift. The National Institute for Occupational Safety and Health has set a recommended exposure limit (REL) for platinum as 1 mg/m3 over an 8-hour workday. Platinum-based antineoplastic agents are used in chemotherapy, and show good activity against some tumors.
Gold resists attacks by individual acids, but it can be dissolved by aqua regia (nitro-hydrochloric acid, literally "royal water"). The acid mixture causes the formation of a soluble gold tetrachloride anion. Gold metal also dissolves in alkaline solutions of cyanide, which are used in mining and electroplating. It is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to refine gold and to confirm the presence of gold in items, giving rise to the term acid test; it dissolves in mercury, though, forming amalgam alloys, but this is not a chemical reaction.
Gold extraction is most economical in large, easily mined deposits. Ore grades as little as 0.5 mg/kg (0.5 parts per million, ppm) can be economical. Typical ore grades in open-pit mines are 1–5 mg/kg (1–5 ppm); ore grades in underground or hard rock mines are usually at least 3 mg/kg (3 ppm). Because ore grades of 30 mg/kg (30 ppm) are usually needed before gold is visible to the naked eye, in most gold mines the gold is invisible. The average gold mining and extraction costs were about US$317/oz in 2007, but these can vary widely depending on mining type and ore quality; global mine production amounted to 2,471.1 tonnes.
Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps and other devices, though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alternatives such as alcohol- or galinstan-filled glass thermometers and thermistor- or infrared-based electronic instruments. Likewise, mechanical pressure gauges and electronic strain gauge sensors have replaced mercury sphygmomanometers. Mercury remains in use in scientific research applications and in amalgam for dental restoration in some locales. It is used in fluorescent lighting. Electricity passed through mercury vapor in a fluorescent lamp produces short-wave ultraviolet light which then causes the phosphor in the tube to fluoresce, making visible light.
Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is obtained by grinding natural cinnabar or synthetic mercuric sulfide.
Mercury poisoning can result from exposure to water-soluble forms of mercury (such as mercuric chloride or methylmercury), by inhalation of mercury vapor, or by eating food contaminated with mercury.
Commercially, however, thallium is produced not from potassium ores, but as a byproduct from refining of heavy metal sulfide ores. Approximately 60–70% of thallium production is used in the electronics industry, and the remainder is used in the pharmaceutical industry and in glass manufacturing. It is also used in infrared detectors. The radioisotope thallium-201 (as the soluble chloride TlCl) is used in small, nontoxic amounts as an agent in a nuclear medicine scan, during one type of nuclear cardiac stress test.
According to the United States Environmental Protection Agency (EPA), man-made sources of thallium pollution include gaseous emission of cement factories, coal burning power plants, and metal sewers. The main source of elevated thallium concentrations in water is the leaching of thallium from ore processing operations
Soluble thallium salts (many of which are nearly tasteless) are highly toxic in quantity, and were historically used in rat poisons and insecticides. Use of these compounds has been restricted or banned in many countries, because of their nonselective toxicity. Notably, thallium poisoning results in hair loss. Because of its historic popularity as a murder weapon, thallium has gained notoriety as "the poisoner's poison" and "inheritance powder" (alongside arsenic).
Fish bones are being researched for their ability to bioremediate lead in contaminated soil. The fungus Aspergillus versicolor is both greatly effective and fast at removing lead ions. Several bacteria have been researched for their ability to reduce lead; including the sulfate reducing bacteria Desulfovibrio and Desulfotomaculum; which are highly effective in aqueous solutions.
Powdered lead burns with a bluish-white flame. As with many metals, finely divided powdered lead exhibits pyrophoricity. Bulk lead released to the air forms a protective layer of insoluble lead oxide, which covers the metal from undergoing further reactions. Other insoluble compounds, such as sulfate or chloride, may form the protective layer if lead is exposed to a different chemical environment. Fluorine reacts with lead at room temperature, forming lead(II) fluoride. The reaction with chlorine is similar, although it requires heating: the chloride layer diminishes the reactivity of the elements.[25][26] Molten lead reacts with chalcogens.
If ingested or inhaled, lead and its compounds are poisonous to animals and humans. Lead is a neurotoxin that accumulates both in soft tissues and the bones, damaging the nervous system and causing brain disorders. Excessive lead also causes blood disorders in mammals. Lead poisoning has been documented since ancient Rome, ancient Greece, and ancient China.
Bismuth subsalicylate is used as an antidiarrheal; it is the active ingredient in such "Pink Bismuth" preparations as Pepto-Bismol, as well as the 2004 reformulation of Kaopectate. It is also used to treat some other gastro-intestinal diseases. The mechanism of action of this substance is still not well documented, although an oligodynamic effect (toxic effect of small doses of heavy metal ions on microbes) may be involved in at least some cases. Salicylic acid from hydrolysis of the compound is antimicrobial for toxogenic E. coli, an important pathogen in traveler's diarrhea.
Bismuth oxychloride (BiOCl) is sometimes used in cosmetics, as a pigment in paint for eye shadows, hair sprays and nail polishes. This compound is found as the mineral bismoclite and in crystal form contains layers of atoms (see figure above) that refract light chromatically, resulting in an iridescent appearance similar to nacre of pearl. It was used as a cosmetic in ancient Egypt and in many places since. Bismuth white (also "Spanish white") can refer to either bismuth oxychloride or bismuth oxynitrate (BiONO3), when used as a white pigment.
Scientific literature concurs that bismuth and most of its compounds are less toxic compared to other heavy metals (lead, antimony, etc.) and that it is not bioaccumulative. They have low solubilities in the blood, are easily removed with urine, and showed no carcinogenic, mutagenic or teratogenic effects in long-term tests on animals (up to 2 years).[83] Its biological half-life for whole-body retention is 5 days but it can remain in the kidney for years in patients treated with bismuth compounds.
Polonium-based sources of alpha particles were produced in the former Soviet Union. Such sources were applied for measuring the thickness of industrial coatings via attenuation of alpha radiation. Because of intense alpha radiation, a one-gram sample of 210Po will spontaneously heat up to above 500 °C (932 °F) generating about 140 watts of power. Therefore, 210Po is used as an atomic heat source to power radioisotope thermoelectric generators via thermoelectric materials. For instance, 210Po heat sources were used in the Lunokhod 1 (1970) and Lunokhod 2 (1973)Moon rovers to keep their internal components warm during the lunar nights, as well as the Kosmos 84 and 90 satellites (1965).
The median lethal dose (LD50) for acute radiation exposure is generally about 4.5 Sv. The committed effective dose equivalent 210Po is 0.51 µSv/Bq if ingested, and 2.5 µSv/Bq if inhaled. So a fatal 4.5 Sv dose can be caused by ingesting 8.8 MBq (240 µCi), about 50 nanograms (ng), or inhaling 1.8 MBq (49 µCi), about 10 ng. One gram of 210Po could thus in theory poison 20 million people of whom 10 million would die. The actual toxicity of 210Po is lower than these estimates, because radiation exposure that is spread out over several weeks (the biological half-life of polonium in humans is 30 to 50 days) is somewhat less damaging than an instantaneous dose. It has been estimated that a median lethal dose of 210Po is 15 megabecquerels (0.41 mCi), or 0.089 micrograms, still an extremely small amount. For comparison, one grain of table salt is about 0.06 mg = 60 μg.
Yes, Polonium-210 in tobacco contributes to many of the cases of lung cancer worldwide. Most of this polonium is derived from lead-210 deposited on tobacco leaves from the atmosphere; the lead-210 is a product of radon-222 gas, much of which appears to originate from the decay of radium-226 from fertilizers applied to the tobacco soils. The presence of polonium in tobacco smoke has been known since the early 1960s. Some of the world's biggest tobacco firms researched ways to remove the substance—to no avail—over a 40-year period. The results were never published.
Newly formed astatine-211 is the subject of ongoing research in nuclear medicine. It must be used quickly as it decays with a half-life of 7.2 hours; this is long enough to permit multistep labeling strategies. Astatine-211 has potential for targeted alpha particle radiotherapy, since it decays either via emission of an alpha particle (to bismuth-207), or via electron capture (to an extremely short-lived nuclide, polonium-211, which undergoes further alpha decay). Polonium X-rays emitted as a result of the electron capture branch, in the range of 77–92 keV, enable the tracking of astatine in animals and patients.
Radon is formed as one intermediate step in the normal radioactive decay chains through which thorium and uranium slowly decay into lead. Thorium and uranium are the two most common radioactive elements on earth; they have been around since the earth was formed. Their naturally occurring isotopes have very long half-lives, on the order of billions of years. Thorium and uranium, their decay product radium, and its decay product radon, will therefore continue to occur for tens of millions of years at almost the same concentrations as they do now.
Yes, Unlike all the other intermediate elements in the aforementioned decay chains, radon is gaseous and easily inhaled. Thus, naturally-occurring radon is responsible for the majority of the public exposure to ionizing radiation. It is often the single largest contributor to an individual's background radiation dose, and is the most variable from location to location. Despite its short lifetime, some radon gas from natural sources can accumulate to far higher than normal concentrations in buildings, especially in low areas such as basements and crawl spaces due to its density. It can also occur in water where the water comes from a ground source -e.g. in some spring waters and hot springs.
An important question is if also passive smoking can cause a similar synergy effect with residential radon. This has been insufficiently studied. The basic data for the European pooling study makes it impossible to exclude that such synergy effect is an explanation for the (very limited) increase in the risk from radon that was stated for non-smokers. A study from 2001, which included 436 cases (never smokers who had lung cancer), and a control group (1649 never smokers) showed that exposure to radon increased the risk of lung cancer in never smokers. But the group that had been exposed to passive smoking at home appeared to bear the entire risk increase, while those who were not exposed to passive smoking did not show any increased risk with increasing radon level.
Radium is not necessary for living organisms, and adverse health effects are likely when it is incorporated into biochemical processes because of its radioactivity and chemical reactivity.
Currently, other than its use in nuclear medicine, radium has no commercial applications; formerly, it was used as a radioactive source for radioluminescent devices and also in radioactive quackery for its supposed curative powers. Today, these former applications are no longer in vogue because radium's toxicity has since become known, and less dangerous isotopes are used instead in radioluminescent devices.
Lanthanum is usually found in combination with cerium and other rare earth elements, and it was first found by the Swedish chemist Carl Gustav Mosander in 1839 as an impurity in cerium nitrate – hence the name lanthanum, from the Greek λανθανειν (lanthanein), meaning "to lie hidden". Although it is classified as a rare earth element, lanthanum is the 28th most abundant element in the Earth's crust, being just under three times as abundant as lead. In minerals such as monazite and bastnäsite, lanthanum makes up over a quarter of the lanthanide content. It is extracted from these minerals using a complex multistage extraction process; due to the complexity of these processes, pure lanthanum metal was not isolated until 1923.
Lanthanum has no known biological role. The element is very poorly absorbed after oral administration and when injected its elimination is very slow. Lanthanum carbonate (Fosrenol) was approved as a phosphate binder to absorb excess phosphate in cases of end stage renal disease. While lanthanum has pharmacological effects on several receptors and ion channels, its specificity for the GABA receptor is unique among trivalent cations. Lanthanum acts at the same modulatory site on the GABA receptor as zinc- a known negative allosteric modulator. The lanthanum cation La3+ is a positive allosteric modulator at native and recombinant GABA receptors, increasing open channel time and decreasing desensitization in a subunit configuration dependent manner.
Lanthanum has a low to moderate level of toxicity and should be handled with care. The injection of lanthanum solutions produces hyperglycemia, low blood pressure, degeneration of the spleen and hepatic alterations. The application in carbon arc light led to the exposure of people to rare earth element oxides and fluorides, sometimes led to pneumoconiosis.
Cerium is the most abundant of the rare earth elements, making up about 0.0046% of the Earth's crust by weight. It is found in a number of minerals, the most important being monazite and bastnäsite. Commercial applications of cerium are numerous. They include catalysts, additives to fuel to reduce emissions and to glass and enamels to change their color. Cerium oxide is an important component of glass polishing powders and phosphors used in screens and fluorescent lamps. It is also used in the "flint" (actually ferrocerium) of lighters.
Cerium can act similar to calcium in organisms, so accumulates in bones in small amounts. Cerium is also found in small amounts in tobacco plants, barley, and the wood of beech trees. However, very little cerium accumulates in the food chain. Human blood contains 0.001 ppm, human bones contain 3 ppm, and human tissue contains 0.3 ppm of cerium. There is a total of 40 milligrams of cerium in a typical 70-kilogram human. Humans typically consume less than a milligram per day of cerium. Cerium (or other lanthanides) are the cofactor for the methanol dehydrogenase of the methanotrophic bacterium Methylacidiphilum fumariolicum SolV. Cerium salts can stimulate metabolism.
Cerium, like all rare-earth metals, is of low to moderate toxicity. Cerium is a strong reducing agent and ignites spontaneously in air at 65 to 80 °C. Fumes from cerium fires are toxic. Water should not be used to stop cerium fires, as cerium reacts with water to produce hydrogen gas. Workers exposed to cerium have experienced itching, sensitivity to heat, and skin lesions. Cerium is not toxic when consumed orally, but animals injected with large doses of cerium have died due to cardiovascular collapse. Cerium is more dangerous to aquatic organisms, on account of being damaging to cell membranes. Cerium(IV) oxide is a powerful oxidizing agent at high temperatures and will react with combustible organic materials. While cerium is not radioactive, the impure commercial grade may contain traces of thorium, which is weakly radioactive.
Praseodymium has no known biological role.
Like all rare earth metals, praseodymium is of low to moderate toxicity.
Use of neodymium is as a component in the alloys used to make high-strength neodymium magnets—powerful permanent magnets. These magnets are widely used in such products as microphones, professional loudspeakers, in-ear headphones, and computer hard disks, where low magnet mass (or volume) or strong magnetic fields are required. Larger neodymium magnets are used in high-power-versus-weight electric motors (for example in hybrid cars) and generators (for example aircraft and wind turbine electric generators)
Neodymium magnets (actually an alloy, Nd2Fe14B) are the strongest permanent magnets known. A neodymium magnet of a few grams can lift a thousand times its own weight. These magnets are cheaper, lighter, and stronger than samarium–cobalt magnets. However, they are not superior in every aspect, as neodymium-based magnets lose their magnetism at comparatively lower[vague] temperatures and tend to rust, while samarium-cobalt magnets do not.
Neodymium metal dust is combustible and therefore an explosion hazard. Neodymium compounds, as with all rare earth metals, are of low to moderate toxicity; however, its toxicity has not been thoroughly investigated. Neodymium dust and salts are very irritating to the eyes and mucous membranes, and moderately irritating to skin. Breathing the dust can cause lung embolisms, and accumulated exposure damages the liver. Neodymium also acts as an anticoagulant, especially when given intravenously.
There are two possible sources for natural promethium: rare decays of natural europium-151 (producing promethium-147), and uranium (various isotopes). Practical applications exist only for chemical compounds of promethium-147, which are used in luminous paint, atomic batteries and thickness measurement devices, even though promethium-145 is the most stable promethium isotope. Because natural promethium is exceedingly scarce, it is typically synthesized by bombarding uranium-235 (enriched uranium) with thermal neutrons to produce promethium-147.
Most promethium is used only for research purposes, except for promethium-147, which can be found outside laboratories. It is obtained as the oxide or chloride, in milligram quantities. This isotope does not emit gamma rays, and its radiation has a relatively small penetration depth in matter and a relatively long half-life. Some signal lights use a luminous paint, containing a phosphor that absorbs the beta radiation emitted by promethium-147 and emits light. This isotope does not cause aging of the phosphor, as alpha emitters do, and therefore the light emission is stable for a few years. Originally, radium-226 was used for the purpose, but it was later replaced by promethium-147 and tritium (hydrogen-3). Promethium may be favored over tritium for safety reasons.
The element, like other lanthanides, has no biological role. Promethium-147 can emit X-rays during its beta decay, which are dangerous for all lifeforms. Interactions with tiny quantities of promethium-147 are not hazardous if certain precautions are observed. In general, gloves, footwear covers, safety glasses, and an outer layer of easily removed protective clothing should be used.
The major commercial application of samarium is in samarium-cobalt magnets, which have permanent magnetization second only to neodymium magnets; however, samarium compounds can withstand significantly higher temperatures, above 700 °C (1,292 °F), without losing their magnetic properties, due to the alloy's higher Curie point. The radioactive isotope samarium-153 is the major component of the drug samarium (153Sm) lexidronam (Quadramet), which kills cancer cells in the treatment of lung cancer, prostate cancer, breast cancer and osteosarcoma.
There are two samarium ions in the active part of the enzyme flap endonuclease 1, which is involved in DNA replication and repair. Samarium salts stimulate metabolism, but it is unclear whether this is the effect of samarium or other lanthanides present with it. The total amount of samarium in adults is about 50 µg, mostly in liver and kidneys and with about 8 µg/L being dissolved in the blood. Samarium is not absorbed by plants to a measurable concentration and therefore is normally not a part of human diet. However, a few plants and vegetables may contain up to 1 part per million of samarium. Insoluble salts of samarium are non-toxic and the soluble ones are only slightly toxic.
It is a dopant in some types of glass in lasers and other optoelectronic devices. Europium oxide (Eu2O3) is widely used as a red phosphor in television sets and fluorescent lamps, and as an activator for yttrium-based phosphors. Color TV screens contain between 0.5 and 1 g of europium oxide. Whereas trivalent europium gives red phosphors, the luminescence of divalent europium depends on the host lattice, but tends to be on the blue side. The two classes of europium-based phosphor (red and blue), combined with the yellow/green terbium phosphors give "white" light, the color temperature of which can be varied by altering the proportion or specific composition of the individual phosphors. This phosphor system is typically encountered in helical fluorescent light bulbs. Combining the same three classes is one way to make trichromatic systems in TV and computer screens. Europium is also used in the manufacture of fluorescent glass. One of the more common persistent after-glow phosphors besides copper-doped zinc sulfide is europium-doped strontium aluminate. Europium fluorescence is used to interrogate biomolecular interactions in drug-discovery screens. It is also used in the anti-counterfeiting phosphors in euro banknotes.
There are no clear indications that europium is particularly toxic compared to other heavy metals. Europium chloride, nitrate and oxide have been tested for toxicity: europium chloride shows an acute intraperitoneal LD50 toxicity of 550 mg/kg and the acute oral LD50 toxicity is 5000 mg/kg. Europium nitrate shows a slightly higher intraperitoneal LD50 toxicity of 320 mg/kg, while the oral toxicity is above 5000 mg/kg. The metal dust presents a fire and explosion hazard.
Gadolinium is paramagnetic at room temperature, with a ferromagnetic Curie point of 20 °C. Paramagnetic ions, such as gadolinium, enhance nuclear relaxation rates. This trait makes gadolinium useful for magnetic resonance imaging (MRI). Solutions of organic gadolinium complexes and gadolinium compounds are used as intravenous MRI contrast agent to enhance images in medical magnetic resonance imaging and magnetic resonance angiography (MRA) procedures. Magnevist is the most widespread example. Nanotubes packed with gadolinium, dubbed "gadonanotubes", are 40 times more effective than this traditional gadolinium contrast agent. Once injected, gadolinium-based contrast agents accumulate in abnormal tissues of the brain and body. This accumulation provides a greater contrast between normal and abnormal tissues, allowing doctors to better locate uncommon cell growths and tumors.
Gadolinium has no known native biological role, but its compounds are used as research tools in biomedicine. Gd3+ compounds are components of MRI contrast agents. It is used in various ion channel electrophysiology experiments to block sodium leak channels and stretch activated ion channels.
Dysprosium is used, in conjunction with vanadium and other elements, in making laser materials and commercial lighting. Because of dysprosium's high thermal-neutron absorption cross-section, dysprosium-oxide–nickel cermets are used in neutron-absorbing control rods in nuclear reactors. Dysprosium–cadmium chalcogenides are sources of infrared radiation, which is useful for studying chemical reactions. Because dysprosium and its compounds are highly susceptible to magnetization, they are employed in various data-storage applications, such as in hard disks.
Like many powders, dysprosium powder may present an explosion hazard when mixed with air and when an ignition source is present. Thin foils of the substance can also be ignited by sparks or by static electricity. Dysprosium fires cannot be put out by water. It can react with water to produce flammable hydrogen gas. Dysprosium chloride fires, however, can be extinguished with water, while dysprosium fluoride and dysprosium oxide are non-flammable. Dysprosium nitrate, Dy(NO3)3, is a strong oxidizing agent and will readily ignite on contact with organic substances.
Holmium has the highest magnetic permeability of any element and therefore is used for the polepieces of the strongest static magnets. Because holmium strongly absorbs neutrons, it is also used as a burnable poison in nuclear reactors.
Holmium plays no biological role in humans, but its salts are able to stimulate metabolism. Humans typically consume about a milligram of holmium a year. Plants do not readily take up holmium from the soil. Some vegetables have had their holmium content measured, and it amounted to 100 parts per trillion.
In addition to optical fiber amplifier-lasers, a large variety of medical applications (i.e. dermatology, dentistry) rely on the erbium ion's 2940 nm emission (see Er:YAG laser), which is highly absorbed in water in tissues, making its effect very superficial. Such shallow tissue deposition of laser energy is helpful in laser surgery, and for the efficient production of steam which produces enamel ablation by common types of dental laser.
Erbium does not have a biological role, but erbium salts can stimulate metabolism. Humans consume 1 milligram of erbium a year on average. The highest concentration of erbium in humans is in the bones, but there is also erbium in the human kidneys and liver.
Thulium is the second least abundant of the lanthanides after promethium, which is only found in trace quantities on Earth. It is an easily workable metal with a bright silvery-gray luster. It is fairly soft and slowly tarnishes in air. Despite its high price and rarity, thulium is used as the radiation source in portable X-ray devices and in solid-state lasers. It has no significant biological role and is not particularly toxic.
There is only a very small amount of thulium in the human body, but the exact amount is unknown. Thulium has not been observed to have a biological role, but small amounts of soluble thulium salts stimulate metabolism.[dubious – discuss] Soluble thulium salts are mildly toxic, but insoluble thulium salts are completely nontoxic. When injected, thulium can cause degeneration of the liver and spleen and can also cause hemoglobin concentration to fluctuate.
Ytterbium clocks hold the record for stability with ticks stable to within less than two parts in 1 quintillion (2×10−18).The clocks developed at the National Institute of Standards and Technology (NIST) rely on about 10,000 rare-earth atoms cooled to 10 microkelvin (10 millionths of a degree above absolute zero) and trapped in an optical lattice—a series of pancake-shaped wells made of laser light. Another laser that "ticks" 518 trillion times per second provokes a transition between two energy levels in the atoms. The large number of atoms is key to the clocks' high stability.
Although ytterbium is fairly stable chemically, it is stored in airtight containers and in an inert atmosphere such as a nitrogen-filled dry box to protect the metal from air and moisture. All compounds of ytterbium are treated as highly toxic, although initial studies appear to indicate that the danger is minimal. Ytterbium compounds are, however, known to cause irritation to the human skin and eyes, and some might be teratogenic. Metallic ytterbium dust can spontaneously combust, and the resulting fumes are hazardous. Ytterbium fires cannot be extinguished using water, and only dry chemical class D fire extinguishers can extinguish the fires.
Because of the rarity and high price, lutetium has very few commercial uses. However, stable lutetium can be used as catalysts in petroleum cracking in refineries and can also be used in alkylation, hydrogenation, and polymerization applications. Lutetium aluminium garnet (Al5Lu3O12) has been proposed for use as a lens material in high refractive index immersion lithography.Additionally, a tiny amount of lutetium is added as a dopant to gadolinium gallium garnet (GGG), which is used in magnetic bubble memory devices. Cerium-doped lutetium oxyorthosilicate (LSO) is currently the preferred compound for detectors in positron emission tomography (PET).[23][24] Lutetium is used as a phosphor in LED light bulbs.
Like other rare-earth metals, lutetium is regarded as having a low degree of toxicity, but its compounds should be handled with care nonetheless: for example, lutetium fluoride inhalation is dangerous and the compound irritates skin.[8] Lutetium nitrate may be dangerous as it may explode and burn once heated. Lutetium oxide powder is toxic as well if inhaled or ingested.
Owing to its scarcity, high price and radioactivity, actinium currently has no significant industrial use. 227Ac is highly radioactive and was therefore studied for use as an active element of radioisotope thermoelectric generators, for example in spacecraft. The oxide of 227Ac pressed with beryllium is also an efficient neutron source with the activity exceeding that of the standard americium-beryllium and radium-beryllium pairs.[38] In all those applications, 227Ac (a beta source) is merely a progenitor which generates alpha-emitting isotopes upon its decay.
227Ac is highly radioactive and experiments with it are carried out in a specially designed laboratory equipped with a glove box. When actinium trichloride is administered intravenously to rats, about 33% of actinium is deposited into the bones and 50% into the liver. Its toxicity is comparable to, but slightly lower than that of americium and plutonium
Thoria is a material for heat-resistant ceramics, as used in high-temperature laboratory crucibles. When added to glass, it helps increase refractive index and decrease dispersion. Such glass finds application in high-quality lenses for cameras and scientific instruments.[9] The radiation from these lenses can darken them and turn them yellow over a period of years and degrade film, but the health risks are minimal. Yellowed lenses may be restored to their original colorless state with lengthy exposure to intense ultraviolet radiation.
As thorium occurs naturally, it exists in very small quantities almost everywhere on Earth: the average human contains about 100 micrograms of thorium and typically consumes three micrograms per day of thorium. This exposure is raised for people who live near uranium, phosphate, or tin processing factories, thorium deposits, radioactive waste disposal sites, and for those who work in uranium, thorium, tin, or phosphate mining or gas mantle production industries. When thorium is ingested, 99.98% does not remain in the body. Out of the thorium that does remain in the body, three quarters of it accumulates in the skeleton. While absorption through the skin is possible, it is not a likely means of thorium exposure.[101] Powdered thorium metal is pyrophoric and often ignites spontaneously in air.
Although protactinium is located in the periodic table between uranium and thorium, which both have numerous applications, owing to its scarcity, high radioactivity and high toxicity, there are currently no uses for protactinium outside of scientific research.
Protactinium is both toxic and highly radioactive and thus all manipulations with it are performed in a sealed glove box. Its major isotope 231Pa has a specific activity of 0.048 curies (1.8 GBq) per gram and primarily emits alpha-particles with an energy of 5 MeV, which can be stopped by a thin layer of any material.
Many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 has the distinction of being the only naturally occurring fissile isotope. Uranium-238 is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor. Another fissile isotope, uranium-233, can be produced from natural thorium and is also important in nuclear technology. While uranium-238 has a small probability for spontaneous fission or even induced fission with fast neutrons, uranium-235 and to a lesser degree uranium-233 have a much higher fission cross-section for slow neutrons. In sufficient concentration, these isotopes maintain a sustained nuclear chain reaction. This generates the heat in nuclear power reactors, and produces the fissile material for nuclear weapons. Depleted uranium (238U) is used in kinetic energy penetrators and armor plating.
Normal functioning of the kidney, brain, liver, heart, and other systems can be affected by uranium exposure, because, besides being weakly radioactive, uranium is a toxic metal. Uranium is also a reproductive toxicant. Radiological effects are generally local because alpha radiation, the primary form of 238U decay, has a very short range, and will not penetrate skin. Uranyl (UO2+2) ions, such as from uranium trioxide or uranyl nitrate and other hexavalent uranium compounds, have been shown to cause birth defects and immune system damage in laboratory animals.
Neptunium accumulates in commercial household ionization-chamber smoke detectors from decay of the (typically) 0.2 microgram of americium-241 initially present as a source of ionizing radiation. With a half-life of 432 years, the americium-241 in an ionization smoke detector includes about 3% neptunium after 20 years, and about 15% after 100 years. Neptunium-237 is the most mobile actinide in the deep geological repository environment. This makes it and its predecessors such as americium-241 candidates of interest for destruction by nuclear transmutation. Due to its long half-life, neptunium will become the major contributor of the total radiotoxicity in 10,000 years. As it is unclear what happens to the containment in that long time span, an extraction of the neptunium would minimize the contamination of the environment if the nuclear waste could be mobilized after several thousand years.
Neptunium does not have a biological role, as it has a short half-life and occurs only in small traces naturally. Animal tests showed that it is not absorbed via the digestive tract. When injected it concentrates in the bones, from which it is slowly released. Finely divided neptunium metal presents a fire hazard because neptunium is pyrophoric; small grains will ignite spontaneously in air at room temperature.
Americium is an artificial element of recent origin, and thus does not have a biological requirement. It is harmful to life. It has been proposed to use bacteria for removal of americium and other heavy metals from rivers and streams. Thus, Enterobacteriaceae of the genus Citrobacter precipitate americium ions from aqueous solutions, binding them into a metal-phosphate complex at their cell walls. Several studies have been reported on the biosorption and bioaccumulation of americium by bacteria and fungi.
As a highly radioactive element, americium and its compounds must be handled only in an appropriate laboratory under special arrangements. Although most americium isotopes predominantly emit alpha particles which can be blocked by thin layers of common materials, many of the daughter products emit gamma-rays and neutrons which have a long penetration depth.
The most practical application of 244Cm — though rather limited in total volume — is as α-particle source in the alpha particle X-ray spectrometers (APXS). These instruments were installed on the Sojourner, Mars, Mars 96, Mars Exploration Rovers and Philae comet lander, as well as the Mars Science Laboratory to analyze the composition and structure of the rocks on the surface of planet Mars. APXS was also used in the Surveyor 5–7 moon probes but with a 242Cm source.
Owing to its high radioactivity, curium and its compounds must be handled in appropriate laboratories under special arrangements. Whereas curium itself mostly emits α-particles which are absorbed by thin layers of common materials, some of its decay products emit significant fractions of beta and gamma radiation, which require a more elaborate protection. If consumed, curium is excreted within a few days and only 0.05% is absorbed in the blood. From there, about 45% goes to the liver, 45% to the bones, and the remaining 10% is excreted. In the bone, curium accumulates on the inside of the interfaces to the bone marrow and does not significantly redistribute with time; its radiation destroys bone marrow and thus stops red blood cell creation. The biological half-life of curium is about 20 years in the liver and 50 years in the bones. Curium is absorbed in the body much more strongly via inhalation, and the allowed total dose of 244Cm in soluble form is 0.3 μC. Intravenous injection of 242Cm and 244Cm containing solutions to rats increased the incidence of bone tumor, and inhalation promoted pulmonary and liver cancer.