In fact, the angiosperms (the dominant type of plant today) and most of their antioxidant pigments evolved during the late Jurassic period. Selenium has seven naturally occurring isotopes. Selenium is not produced in the body, but it is needed for proper thyroid and immune system function.  Ruminants grazing certain forages, e.g., some white clover varieties containing cyanogenic glycosides, may have higher selenium requirements, presumably because cyanide is released from the aglycone by glucosidase activity in the rumen and glutathione peroxidases is deactivated by the cyanide acting on the glutathione moiety. , Selenium is used with bismuth in brasses to replace more toxic lead. Because of its similarity to tellurium, named for the Earth, Berzelius named the new element after the Moon.. Although trace amounts of selenium are necessary for cellular function in many animals, including humans, both elemental selenium and (especially) selenium salts are toxic in even small doses, causing selenosis.  The resultant high selenium levels in waterways were found to cause congenital disorders in oviparous species, including wetland birds and fish. A few of these appeared more recently, in the last 50–200 million years, in fruits and flowers of angiosperm plants.  These lasted in commercial applications until the 1970s, following which they were replaced with less expensive and even more efficient silicon rectifiers. What is the formula for the ionic compound formed by calcium and selenium? , From about three billion years ago, prokaryotic selenoprotein families drive the evolution of selenocysteine, an amino acid. Rev. Selenoprotein families of GSH-Px and the deiodinases of eukaryotic cells seem to have a bacterial phylogenetic origin. Selenium is most commonly found as an impurity, replacing a small part of the sulfur in sulfide ores of many metals. , Although selenium is an essential trace element, it is toxic if taken in excess.  With so many humans consuming fish as a source of protein, it is important to be aware of the selenium pollution occurring in the oceans they get their fish from so we know what we are putting in our bodies. The regulation of lead in drinking water applications such as in the US with the Safe Drinking Water Act of 1974, made a reduction of lead in brass necessary. Another selenium-bearing enzyme in some plants and in animals (thioredoxin reductase) generates reduced thioredoxin, a dithiol that serves as an electron source for peroxidases and also the important reducing enzyme ribonucleotide reductase that makes DNA precursors from RNA precursors. Selenium forms two oxides: selenium dioxide (SeO2) and selenium trioxide (SeO3). and Informatics, https://doi.org/10.1103/PhysRevA.85.015401, Free energy of reaction at standard conditions, Enthalpy of reaction at standard conditions. For other applications, a red color may be desired, produced by mixtures of CdSe and CdS. The selenite anion is a selenium oxoanion with the chemical formula SeO 2− 3.. A selenite (compound) is a compound that contains this ion.. The sulfoxide in sulfur chemistry is represented in selenium chemistry by the selenoxides (formula RSe(O)R), which are intermediates in organic synthesis, as illustrated by the selenoxide elimination reaction. Berzelius and Gahn wanted to use the pyrite and they also observed that the red precipitate gave off a smell like horseradish when burned. Unlike the other allotropes, it is insoluble in CS2. Zinc selenide was the first material for blue LEDs, but gallium nitride dominates that market. Database and to verify that the data contained therein have This smell was not typical of arsenic, but a similar odor was known from tellurium compounds. Therefore the formula for selenium monoxide is SeO. This hydrolysis occurs because of the extreme basicity of the Se 2− ion. For this purpose, various selenite and selenate salts are added. , The most stable and dense form of selenium is gray and has a hexagonal crystal lattice consisting of helical polymeric chains, where the Se-Se distance is 237.3 pm and Se-Se-Se angle is 130.1° . Selenide is an ion. The selenium cell was used in the photophone developed by Alexander Graham Bell in 1879. Some of the selenium oxyhalides, such as selenium oxyfluoride (SeOF2) and selenium oxychloride (SeOCl2) have been used as specialty solvents. In plants, it occurs as a bystander mineral[clarification needed], sometimes in toxic proportions in forage (some plants may accumulate selenium as a defense against being eaten by animals, but other plants, such as locoweed, require selenium, and their growth indicates the presence of selenium in soil). , About 2,000 tonnes of selenium were produced in 2011 worldwide, mostly in Germany (650 t), Japan (630 t), Belgium (200 t), and Russia (140 t), and the total reserves were estimated at 93,000 tonnes. SO, the number of Ion is -2. because to far or difficult to donate 6. , In fish and other wildlife, selenium is necessary for life, but toxic in high doses. 22788-28-9 [all data], Go To: Top, Gas phase ion energetics data, References. These findings suggest that, with the exception of vertebrates, aquatic life supports selenium use, whereas terrestrial habitats lead to reduced use of this trace element. All rights reserved. A, 2012, 85, 1, 015401, https://doi.org/10.1103/PhysRevA.85.015401  Hydrogen selenide is an extremely toxic, corrosive gas. Salts of selenous acid are called selenites. Sources of pollution include waste materials from certain mining, agricultural, petrochemical, and industrial manufacturing operations. 104791. , Selenium reacts with cyanides to yield selenocyanates:, Selenium, especially in the II oxidation state, forms stable bonds to carbon, which are structurally analogous to the corresponding organosulfur compounds. Copyright for NIST Standard Reference Data is governed by These data exclude two major producers: the United States and China. 6397996. Selenium compounds commonly exist in the oxidation states −2, +2, +4, and +6. What is the formula for the ionic compound formed by calcium ions and nitrate ions? The selenocysteine-containing form occurs in species as diverse as green algae, diatoms, sea urchins, fish, and chickens. Selenium rectifiers were first used in 1933. In solution it is a diprotic acid: H 2 SeO 3 ⇌ H + + HSeO − 3 (pK a = 2.62) HSeO − 3 ⇌ H + + SeO 2− 3 (pK a = 8.32) © 2018 by the U.S. Secretary of Commerce  Neonate ruminants at risk of white muscle disease may be administered both selenium and vitamin E by injection; some of the WMD myopathies respond only to selenium, some only to vitamin E, and some to either. This color cancels out the green or yellow tints that arise from iron impurities typical for most glass. Further concentration through bioaccumulation occurs along the food chain, as predators consume selenium rich prey.  Elevated dietary methylmercury levels can amplify the harm of selenium toxicity in oviparous species. When prepared in chemical reactions, selenium is usually an amorphous, brick-red powder. , Anthropogenic sources of selenium include coal burning, and the mining and smelting of sulfide ores. On 19 April 2009, 21 polo ponies died shortly before a match in the United States Polo Open. Also naturally occurring is the long-lived primordial radionuclide 82Se, with a half-life of 9.2×1019 years. Consistent with trends indicated by the double bond rule, selenoketones, R(C=Se)R, and selenaldehydes, R(C=Se)H, are rarely observed. Further studies are needed to confirm these interactions. 16. Selenous acid is bubbled with sulfur dioxide (reduction step) to give elemental selenium. What is the formula for the ionic compound formed by calcium and selenium? See more Selenium products. Selenides are reducing agents when pure. In 1954, the first hints of specific biological functions of selenium were discovered in microorganisms by biochemist, Jane Pinsent.  Isolation of selenium is often complicated by the presence of other compounds and elements. ), Selenium may inhibit Hashimoto's disease, in which the body's own thyroid cells are attacked as foreign. Tetraselenium tetranitride, Se4N4, is an explosive orange compound analogous to tetrasulfur tetranitride (S4N4). Magnesium and selenium Express your answers as ions and chemical formula separated by a commas. Copper has two common ion charges, Cu+ and Cu2+. (i) Selenium forms an ionic compound with potassium. Use o to represent an electron from an atom of potassium. References The data on these compounds pages are assembled and adapted from the primary literature and several other sources including the following. a. Se^-2, selenide ion b. Ba^+2 + 2e^-, barium ion c. P^-3, phosphide ion d. I^-, iodide ion. , This article is about the chemical element. been selected on the basis of sound scientific judgment. Selenium came to medical notice later because of its toxicity to industrial workers. , In the regions (e.g. Data compilation copyright Se2. National Institute of Standards and Selenium (atomic symbol: Se, atomic number: 34) is a Block P, Group 16, Period 4 element with an atomic radius of 78.96. In high concentrations, selenium acts as an environmental contaminant. Synonyms. Small amounts of organoselenium compounds have been used to modify the catalysts used for the vulcanization for the production of rubber..  This 400 µg Tolerable Upper Intake Level is based primarily on a 1986 study of five Chinese patients who exhibited overt signs of selenosis and a follow up study on the same five people in 1992. Selenium is an ingredient in many multivitamins and other dietary supplements, including infant formula. Data from NIST Standard Reference Database 69: The National Institute of Standards and Technology (NIST) , Dietary selenium comes from meat, nuts, cereals and mushrooms. The pyrite from the Falun Mine created a red precipitate in the lead chambers which was presumed to be an arsenic compound, so the pyrite's use to make acid was discontinued. , Selenium poisoning of water systems may result whenever new agricultural runoff courses through normally dry, undeveloped lands.  Also, selenium interacts with other minerals, such as zinc and copper. Inorganic selenium bioaccumulates more readily in phytoplankton than zooplankton. They all have relatively low, monoclinic crystal symmetries and contain nearly identical puckered Se8 rings with different arrangements, as in sulfur. Selenium's semiconductor properties found numerous other applications in electronics. Other problems include degeneration of liver tissue, swelling around the heart, damaged egg follicles in ovaries, cataracts, and accumulation of fluid in the body cavity and head. Three days later, a pharmacy released a statement explaining that the horses had received an incorrect dose of one of the ingredients used in a vitamin/mineral supplement compound that had been incorrectly prepared by a compounding pharmacy. How many electrons were lost or gained to form these ions? , The selenium content in the human body is believed to be in the 13–20 mg range. Electron affinity of selenium measured by photodetachment microscopy, Selenium occurs naturally in a number of inorganic forms, including selenide, selenate, and selenite, but these minerals are rare.  Like lead and sulfur, selenium improves the machinability of steel at concentrations around 0.15%. , Although it is toxic in large doses, selenium is an essential micronutrient for animals. It is involved as a catalyst in several important enzymes. Ka W. asked • 10/17/19 What is the chemical formula that results when sodium and selenium combine to form an ionic bond? Vandevraye, M.; Drag, C.; Blondel, C., By contrast, selenates and selenites have an oxidant mode of action similar to that of arsenic trioxide and are very toxic.  It has also been suggested that season could have an impact on the harmful effects of selenium on fish. Selenium dioxide is formed by the reaction of elemental selenium with oxygen:, It is a polymeric solid that forms monomeric SeO2 molecules in the gas phase. Selenium transmits an electric current proportional to the amount of light falling on its surface. Selenium tetrabromide. Sheets of amorphous selenium convert X-ray images to patterns of charge in xeroradiography and in solid-state, flat-panel X-ray cameras.  The development of selenium rectifiers began during the early 1930s, and these replaced copper oxide rectifiers because they were more efficient. Formula: Se-Molecular weight: 78.96; Information on this page: Gas phase ion energetics data; References; Notes; Other data available: Reaction … , Industrial production of selenium usually involves the extraction of selenium dioxide from residues obtained during the purification of copper. shall not be liable for any damage that may result from selenium anion. The chemistry of the selenides and sulfides is similar. The recoding mechanism was worked out first in bacteria and then in mammals (see SECIS element).. ions, formula = rubidium and phosphorus Express your answers as ions and chemical formula separated by a commas. Selenium is found in metal sulfide ores, where it partially replaces the sulfur. SeBr4 or Br4Se. Selenium dichloride is an important reagent in the preparation of selenium compounds (e.g. , Selenium deficiency can occur in patients with severely compromised intestinal function, those undergoing total parenteral nutrition, and in those of advanced age (over 90). ... An ionic molecule with a formula of CsO_2 is possible. The price was relatively stable during 2004–2010 at about US$30 per pound (in 100 pound lots) but increased to $65/lb in 2011. During the 1980s, selenocysteine was shown to be encoded by the codon UGA. Michiaki Yamashita, Shintaro Imamura, Md. Common production from the residue then begins by oxidation with sodium carbonate to produce selenium dioxide, which is mixed with water and acidified to form selenous acid (oxidation step). Other selenium allotropes may contain Se6 or Se7 rings. In solution it ionizes to HSe−. Minerals that are pure selenide or selenate compounds are known but rare. Electrolytic metal refining is particularly productive of selenium as a byproduct, obtained from the anode mud of copper refineries. I was thinking Krypton because it is a noble gas and it is the closest to Selenium but I am not sure. However, it can damage plants at higher doses. Cancer patients receiving daily oral doses of selenothionine may achieve very high plasma and urine selenium concentrations. selenium, vanadium, magnesium, copper, and zinc, may have been lacking in some terrestrial mineral-deficient areas. Na_4PO_4.  About 200 million years ago, new selenoproteins were developed as mammalian GSH-Px enzymes. 3.4 Naming Ionic Compounds Multiple-choice questions 15. ions, formula Previous Answers Request Answer Submit Part C sodium and phosphorus Express your answers as ions and chemical formula separated by a commas.  There are, however, a few species that have been seen to survive these events and tolerate the increased selenium. In Belews Lake North Carolina, 19 species of fish were eliminated from the lake due to 150-200 μg Se/L wastewater discharged from 1974 to 1986 from a Duke Energy coal-fired power plant. , During the electrowinning of manganese, the addition of selenium dioxide decreases the power necessary to operate the electrolysis cells.  Isotopes lighter than the stable isotopes primarily undergo beta plus decay to isotopes of arsenic, and isotopes heavier than the stable isotopes undergo beta minus decay to isotopes of bromine, with some minor neutron emission branches in the heaviest known isotopes. Fish affected by selenium may experience swelling of the gill lamellae, which impedes oxygen diffusion across the gills and blood flow within the gills. Select the correct name of Pd 4+ a. palladium(iv) ion b. palladium (4) ion c. palladium 4+ ion d. palladium ion 17. In humans, selenium is a trace element nutrient that functions as cofactor for reduction of antioxidant enzymes, such as glutathione peroxidases and certain forms of thioredoxin reductase found in animals and some plants (this enzyme occurs in all living organisms, but not all forms of it in plants require selenium). Chromium (III) oxide. , Selenium forms several allotropes that interconvert with temperature changes, depending somewhat on the rate of temperature change. Selenium is a component of the unusual amino acids selenocysteine and selenomethionine. ions, formula = Previous Answers Submit Reauest Answer Especially common are selenides (R2Se, analogues of thioethers), diselenides (R2Se2, analogues of disulfides), and selenols (RSeH, analogues of thiols). It dissolves in water to form selenous acid, H2SeO3. Molecular Formula. The glutathione peroxidase family of enzymes (GSH-Px) catalyze certain reactions that remove reactive oxygen species such as hydrogen peroxide and organic hydroperoxides: The thyroid gland and every cell that uses thyroid hormone use selenium, which is a cofactor for the three of the four known types of thyroid hormone deiodinases, which activate and then deactivate various thyroid hormones and their metabolites; the iodothyronine deiodinases are the subfamily of deiodinase enzymes that use selenium as the otherwise rare amino acid selenocysteine. As a crystalline solid, the compound can be seen as pyramidal molecules that are interconnected with hydrogen bonds. : A previous sharp increase was observed in 2004 from $4–$5 to $27/lb. The selenide dianion Se2− forms a variety of compounds, including the minerals from which selenium is obtained commercially. However, NIST makes no warranties to that effect, and NIST I am not sure about this. Selenium was also recognized as an important veterinary toxin, which is seen in animals that have eaten high-selenium plants. Part B rubidium and selenium Express your answers as ions and chemical formula separated by a commas. Anwar Hossain, Ken Touhata, Takeshi Yabu, and Yumiko Yamashita, CS1 maint: multiple names: authors list (. , Certain soils are selenium-rich, and selenium can be bioconcentrated by some plants. Selenium poisoning can be passed from parents to offspring through the egg, and selenium poisoning may persist for many generations.  Its photovoltaic and photoconductive properties are still useful in photocopying, photocells, light meters and solar cells. UNII-8O54YXR180.  It can be synthesized by the reaction of selenium tetrachloride (SeCl4) with [((CH3)3Si)2N]2Se. The lithium–selenium (Li–Se) battery is one of the most promising systems for energy storage in the family of lithium batteries. However, most elemental selenium comes as a byproduct of refining copper or producing sulfuric acid. Technology, Office of Data Selenium is incorporated into several prokaryotic selenoprotein families in bacteria, archaea, and eukaryotes as selenocysteine, where selenoprotein peroxiredoxins protect bacterial and eukaryotic cells against oxidative damage. Selenium does not exhibit the changes in viscosity that sulfur undergoes when gradually heated. , Selenium is used in the toning of photographic prints, and it is sold as a toner by numerous photographic manufacturers. Selenium is found in metal sulfide ores, where it partially replaces sulfur (Wikipedia, 2015). , Increased dietary selenium reduces the effects of mercury toxicity, although it is effective only at low to modest doses of mercury. In X-ray crystallography, incorporation of one or more selenium atoms in place of sulfur helps with multiple-wavelength anomalous dispersion and single wavelength anomalous dispersion phasing. Organoselenium compounds can be concentrated over 200,000 times by zooplankton when water concentrations are in the 0.5 to 0.8 μg Se/L range. This process leaches natural soluble selenium compounds (such as selenates) into the water, which may then be concentrated in new "wetlands" as the water evaporates.  To help reduce the amount of selenium entering our oceans, policies can be put into place such as using microbes or enzymes that target and break down metalloids like selenium. At the Kesterson National Wildlife Refuge in California, thousands of fish and waterbirds were poisoned by selenium in agricultural irrigation drainage. The subscripts for the base formula can be determined using either of the methods described above. Respiratory capacity is further reduced due to selenium binding to hemoglobin. The ion symbol for the cation is currently written first, as is required in an ionic chemical formula, so the order in which the ions are written should not change.
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