Platinum is one of the least reactive metals. Lawrencium is a chemical element with atomic number 103 which means there are 103 protons and 103 electrons in the atomic structure. When prepared in chemical reactions, selenium is usually an amorphous, brick-red powder. There are only 5 parts per billion of tellurium in the earth's crust and 15 parts per billion of tellurium in seawater. Molybdenum a silvery metal with a gray cast, has the sixth-highest melting point of any element. The chemical symbol for Polonium is Po. The unit of measure for mass is the atomic mass unit (amu). Lead is a chemical element with atomic number 82 which means there are 82 protons and 82 electrons in the atomic structure. Selenium ek chemical element hae jiske chemical symbol Se, atomic number 34 aur mass number 78.96 hae. [100] Marine fishes and vertebrate thyroid glands have the highest concentration of selenium and iodine. [81] 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. Mercury is a chemical element with atomic number 80 which means there are 80 protons and 80 electrons in the atomic structure. Selenium disulfide has been used in shampoo as an antidandruff agent, an inhibitor in polymer chemistry, a glass dye, and a reducing agent in fireworks. For salmon, the optimal concentration of selenium is about 1 microgram selenium per gram of whole body weight. The origin of the name comes from the Greek word selene meaning moon. [56], During the electrowinning of manganese, the addition of selenium dioxide decreases the power necessary to operate the electrolysis cells. The chemical symbol for Oxygen is O. Selenium is a chemical element with atomic number 34 and symbol Se. Inorganic selenium bioaccumulates more readily in phytoplankton than zooplankton. Titanium can be used in surface condensers. Extreme cases of selenosis can exhibit cirrhosis of the liver, pulmonary edema, or death. The common mineral selenite is not a selenium mineral, and contains no selenite ion, but is rather a type of gypsum (calcium sulfate hydrate) named like selenium for the moon well before the discovery of selenium. 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). It rarely occurs in its elemental state or as pure ore compounds in the Earth’s crust. Zirconium is widely used as a cladding for nuclear reactor fuels. This is a list of chemical elements, sorted by atomic mass (or most stable isotope) and color coded according to type of element.Each element's atomic number, name, element symbol, and group and period numbers on the periodic table are given. Selenium is incorporated into several prokaryotic selenoprotein families in bacteria, archaea, and eukaryotes as selenocysteine,[98] where selenoprotein peroxiredoxins protect bacterial and eukaryotic cells against oxidative damage. All of its isotopes are radioactive. Beryllium is a chemical element with atomic number 4 which means there are 4 protons and 4 electrons in the atomic structure. Atomic Mass of Selenium. The chemical symbol for Hafnium is Hf. At levels of 1 mg/m3, selenium is immediately dangerous to life and health. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer (passivation) stabilizes the free metal somewhat against further oxidation. Because of its closed-shell electron configuration, its density and melting and boiling points differ significantly from those of most other lanthanides. Anwar Hossain, Ken Touhata, Takeshi Yabu, and Yumiko Yamashita, CS1 maint: multiple names: authors list (. Substantial physiological changes may occur in fish with high tissue concentrations of selenium. Diagram of the nuclear composition and electron configuration of an atom of selenium-80 (atomic number: 34), the most common isotope of this element. Its properties are thus intermediate between those of chlorine and iodine. These include silver selenite (Ag2SeO3) and sodium selenite (Na2SeO3). In nuclear industry, especially artificial xenon 135 has a tremendous impact on the operation of a nuclear reactor. The chemical symbol for Bromine is Br. Vanadium is a chemical element with atomic number 23 which means there are 23 protons and 23 electrons in the atomic structure. 1) You may use almost everything for non-commercial and educational use. [102][103][104][105], Dietary selenium comes from meat, nuts, cereals and mushrooms. The metal is found in the Earth’s crust in the pure, free elemental form (“native silver”), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. The chemical symbol for Samarium is Sm. [30][31][32] The development of selenium rectifiers began during the early 1930s, and these replaced copper oxide rectifiers because they were more efficient. Under standard conditions, it is the lightest metal and the lightest solid element. Bismuth is a chemical element with atomic number 83 which means there are 83 protons and 83 electrons in the atomic structure. Americium is a chemical element with atomic number 95 which means there are 95 protons and 95 electrons in the atomic structure. Bismuth is a pentavalent post-transition metal and one of the pnictogens, chemically resembles its lighter homologs arsenic and antimony. – kaufen Sie diese Vektorgrafik und finden Sie ähnliche Vektorgrafiken auf Adobe Stock The chemical symbol for Caesium is Cs. Discoverer: Scientists at Dubna, Russia (1964)/Albert Ghiorso et. In nuclear reactors, promethium equilibrium exists in power operation. The chemical symbol for Magnesium is Mg. Magnesium is a shiny gray solid which bears a close physical resemblance to the other five elements in the second column (group 2, or alkaline earth metals) of the periodic table: all group 2 elements have the same electron configuration in the outer electron shell and a similar crystal structure. The chemical symbol for Argon is Ar. Related terms: Arsenic ; Tellurium; Selenites; Protein; Peroxidase; Glutathione; Annealing; View all Topics. [23], Selenium reacts with cyanides to yield selenocyanates:[6], Selenium, especially in the II oxidation state, forms stable bonds to carbon, which are structurally analogous to the corresponding organosulfur compounds. Cerium is a soft, ductile and silvery-white metal that tarnishes when exposed to air, and it is soft enough to be cut with a knife. Chemically, indium is similar to gallium and thallium. These condensers use tubes that are usually made of stainless steel, copper alloys, or titanium depending on several selection criteria (such as thermal conductivity or corrosion resistance). Discoverer: Davy, Sir H. and Thénard, L.-J. Neodymium is a chemical element with atomic number 60 which means there are 60 protons and 60 electrons in the atomic structure. The chemical symbol for Sodium is Na. Since nucleons (protons and neutrons) make up most of the mass of ordinary atoms, the density of normal matter tends to be limited by how closely we can pack these nucleons and depends on the internal atomic structure of a substance. [55], Researchers found that application of selenium fertilizer to lettuce crops decreased the accumulation of lead and cadmium. Minerals that are pure selenide or selenate compounds are known but rare. Though once widely used, selenium rectifiers have mostly been replaced (or are being replaced) by silicon-based devices. The chemical symbol for Lanthanum is La. Naturally occurring potassium is composed of three isotopes, of which 40K is radioactive. Mendelevium is a metallic radioactive transuranic element in the actinide series, it is the first element that currently cannot be produced in macroscopic quantities. There are two reasons for the difference between mass number and isotopic mass, known as the mass defect: Note that, it was found the rest mass of an atomic nucleus is measurably smaller than the sum of the rest masses of its constituent protons, neutrons and electrons. It is fairly soft and slowly tarnishes in air. Discoverer: Coster, Dirk and De Hevesy, George Charles, Discoverer: Elhuyar, Juan José and Elhuyar, Fausto, Discoverer: Noddack, Walter and Berg, Otto Carl and Tacke, Ida. Its abundance in rocky planets like Earth is due to its abundant production by fusion in high-mass stars. Selenium is a metalloid with atomic number 34 (discovered in 1817 by J. J. Berzelius) that has been demonstrated to be essential for living organisms. [139], It has been suggested that selenium supplementation may help prevent cancer incidence in people, but research has established there is no evidence to support such claims. The chemical symbol for Antimony is Sb. [132], Selenium interacts with other nutrients, such as iodine and vitamin E. The effect of selenium deficiency on health remains uncertain, particularly in relation to Kashin-Beck disease. [6][8], Owing to its use as a photoconductor in flat-panel x-ray detectors (see below), the optical properties of amorphous selenium (α-Se) thin films have been the subject of intense research.[9][10][11]. Plutonium is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. Nearly all technetium is produced synthetically, and only minute amounts are found in the Earth’s crust. Atomic mass of Selenium is 78.96 u. In these compounds, selenium plays a role analogous to that of sulfur. The chemical symbol for Strontium is Sr. Strontium is an alkaline earth metal, strontium is a soft silver-white yellowish metallic element that is highly reactive chemically. [84] 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. The selenocysteine-containing form occurs in species as diverse as green algae, diatoms, sea urchins, fish, and chickens. Respiratory capacity is further reduced due to selenium binding to hemoglobin. Scandium is a silvery-white metallic d-block element, it has historically been sometimes classified as a rare-earth element, together with yttrium and the lanthanides. Small amounts of organoselenium compounds have been used to modify the catalysts used for the vulcanization for the production of rubber.[52]. ), woody asters (Xylorhiza sp. [120] The resultant high selenium levels in waterways were found to cause congenital disorders in oviparous species, including wetland birds[121] and fish. [59] Like lead and sulfur, selenium improves the machinability of steel at concentrations around 0.15%. Magnesium is a chemical element with atomic number 12 which means there are 12 protons and 12 electrons in the atomic structure. Aluminium is a silvery-white, soft, nonmagnetic, ductile metal in the boron group. [109], Certain species of plants are considered indicators of high selenium content of the soil because they require high levels of selenium to thrive. Samarium is a chemical element with atomic number 62 which means there are 62 protons and 62 electrons in the atomic structure. Palladium, platinum, rhodium, ruthenium, iridium and osmium form a group of elements referred to as the platinum group metals (PGMs). it exists in the form of ores and minerals. Mass numbers of typical isotopes of Selenium are 74; 76; 77; 78; 80. Element : Symbol : Atomic Mass # of Atoms : Mass Percent: Selenium: Se: 78.96: 1: 100.000% ›› Calculate the molecular weight of a chemical compound. Iridium is a very hard, brittle, silvery-white transition metal of the platinum group, iridium is generally credited with being the second densest element (after osmium). [33][34][35] These lasted in commercial applications until the 1970s, following which they were replaced with less expensive and even more efficient silicon rectifiers. In fact, the angiosperms (the dominant type of plant today) and most of their antioxidant pigments evolved during the late Jurassic period. Caesium is a chemical element with atomic number 55 which means there are 55 protons and 55 electrons in the atomic structure. [73], Selenium is a catalyst in some chemical reactions, but it is not widely used because of issues with toxicity. Peaches and pears given a foliar selenium spray contained higher levels selenium and also stayed firm and ripe longer when in storage. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with about two-thirds the density of air. Cadmium is a soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. The atomic mass or relative isotopic mass refers to the mass of a single particle, and therefore is tied to a certain specific isotope of an element. Convert grams Selenium to moles or moles Selenium to grams ›› Percent composition by element. [80] Fish are a major source of protein for humans. The chemical symbol for Fermium is Fm. As the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine. Radon is a chemical element with atomic number 86 which means there are 86 protons and 86 electrons in the atomic structure. [97], From about three billion years ago, prokaryotic selenoprotein families drive the evolution of selenocysteine, an amino acid. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium. Selenium—from Ancient Greek σελήνη (selḗnē) "Moon" – was discovered in 1817 by Jöns Jacob Berzelius, who noted the similarity of the new element to the previously discovered tellurium (named for the Earth). Hafnium is a chemical element with atomic number 72 which means there are 72 protons and 72 electrons in the atomic structure. The packing is most dense in the α form. Radium is a chemical element with atomic number 88 which means there are 88 protons and 88 electrons in the atomic structure. Selenium (atomic symbol: Se, atomic number: 34) is a Block P, Group 16, Period 4 element with an atomic radius of 78.96. Molar mass of Se = 78.96 g/mol. Like the other metals of the platinum group, ruthenium is inert to most other chemicals. Selenium poisoning can be passed from parents to offspring through the egg, and selenium poisoning may persist for many generations. Lawrencium is the final member of the actinide series. The atomic mass is the mass of an atom. Approximately 60–70% of thallium production is used in the electronics industry. Atomic mass of Selenium is 78.96 u. [clarification needed]. [7], 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° . The commercial use of beryllium requires the use of appropriate dust control equipment and industrial controls at all times because of the toxicity of inhaled beryllium-containing dusts that can cause a chronic life-threatening allergic disease in some people called berylliosis. Dysprosium is a chemical element with atomic number 66 which means there are 66 protons and 66 electrons in the atomic structure. 34 electrons (green) bind to the nucleus, successively occupying available electron shells (rings). Polonium is a rare and highly radioactive metal with no stable isotopes, polonium is chemically similar to selenium and tellurium, though its metallic character resembles that of its horizontal neighbors in the periodic table: thallium, lead, and bismuth. Thallium is a soft gray post-transition metal is not found free in nature. The chemical symbol for Gadolinium is Gd. Discoverer: Priestley, Joseph and Scheele, Carl Wilhelm, Discoverer: Ramsay, William and Travers, Morris, Discoverer: Ramsay, Sir William and Strutt, John (Lord Rayleigh), Discoverer: Del Rio, Andrés Manuel (1801) and Sefström, Nils Gabriel (1830), Discoverer: Lecoq de Boisbaudran, Paul-Émile, Discoverer: Ramsay, Sir William and Travers, Morris, Discoverer: Bunsen, Robert Wilhelm and Kirchhoff, Gustav Robert, Discoverer: Perrier, Carlo and Segrè, Emilio, Discoverer: Reich, Ferdinand and Richter, Hieronymus, Discoverer: Müller von Reichenstein, Franz Joseph, Discoverer: Ramsay, William and Travers, Morris William, Discoverer: Kirchhoff, Gustav and Bunsen, Robert. Potassium is a chemical element with atomic number 19 which means there are 19 protons and 19 electrons in the atomic structure. Representatives of selenides, diselenides, and selenols include respectively selenomethionine, diphenyldiselenide, and benzeneselenol. The chemical symbol for Ytterbium is Yb. Download as PDF. The chemical symbol for Krypton is Kr. Berkelium is a member of the actinide and transuranium element series. The chemical symbol for Helium is He. Francium is the second-least electronegative element, behind only caesium, and is the second rarest naturally occurring element (after astatine). Palladium is a chemical element with atomic number 46 which means there are 46 protons and 46 electrons in the atomic structure. Radon is a radioactive, colorless, odorless, tasteless noble gas. The chemical symbol for Aluminum is Al. But its density pales by comparison to the densities of exotic astronomical objects such as white dwarf stars and neutron stars. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype. Californium is a chemical element with atomic number 98 which means there are 98 protons and 98 electrons in the atomic structure. 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. Einsteinium is the seventh transuranic element, and an actinide. About this page. The US Recommended Dietary Allowance (RDA) of selenium for teenagers and adults is 55 µg/day. Their use continued into the 1990s. Selenium is not an abundant element. Selenium is a nonmetal with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, and also has similarities to arsenic. The atomic mass or relative isotopic mass refers to the mass of a single particle, and therefore is tied to a certain specific isotope of an element. The chemical symbol for Neon is Ne. Units of measure have been defined for mass and energy on the atomic scale to make measurements more convenient to express. Titanium is resistant to corrosion in sea water, aqua regia, and chlorine. [46][47], Anthropogenic sources of selenium include coal burning, and the mining and smelting of sulfide ores. The chemical symbol for Lutetium is Lu. [134], In the regions (e.g. The chemical symbol for Phosphorus is P. As an element, phosphorus exists in two major forms—white phosphorus and red phosphorus—but because it is highly reactive, phosphorus is never found as a free element on Earth. These have similar chemical properties, but palladium has the lowest melting point and is the least dense of them. The chemical symbol for Radium is Ra. In fact their absorption cross-sections are the highest among all stable isotopes. This coal was shown to have selenium content as high as 9.1%, the highest concentration in coal ever recorded.[115]. Helium is a chemical element with atomic number 2 which means there are 2 protons and 2 electrons in the atomic structure. Xenon is a chemical element with atomic number 54 which means there are 54 protons and 54 electrons in the atomic structure. Density is defined as the mass per unit volume. Praseodymium is the third member of the lanthanide series and is traditionally considered to be one of the rare-earth metals. Selenium A r (Se) = 78.971(8) since 2013 The name derives from the Greek Selene, who was the Greek goddess of the Moon because the element is chemically found with tellurium (Tellus was the Roman goddess of the Earth). In solution it ionizes to HSe−. Selenium: Symbol: Se: Atomic Number: 34: Atomic Mass: 78.96 atomic mass units Number of Protons: 34: Number of Neutrons: 45: Number of Electrons: 34: Melting Point: 217.0° C: Boiling Point: 684.9° C: Density: 4.79 grams per cubic centimeter: Normal Phase: Solid: Family: Nonmetals: Period: 4: Costs: $300 per pound The chemical symbol for Calcium is Ca. [116] Elemental selenium and most metallic selenides have relatively low toxicities because of low bioavailability. Classification: Non-metal. It is an intensive property, which is mathematically defined as mass divided by volume: In words, the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance. It is a synthetic element (first synthesised at Hasse in Germany) and radioactive. Number of Neutrons: 45. Reproduction of mallard ducks is impaired at dietary concentrations of 7 ug Se/L. These data exclude two major producers: the United States and China. 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. The chemical symbol for Francium is Fr. [15], Selenium trioxide may be synthesized by dehydrating selenic acid, H2SeO4, which is itself produced by the oxidation of selenium dioxide with hydrogen peroxide:[17], Hot, concentrated selenic acid can react with gold to form gold(III) selenate.[18]. Holmium is a relatively soft and malleable silvery-white metal. Selenium can be refined from these muds by a number of methods. Hydrogen sulfide reacts with aqueous selenous acid to produce selenium disulfide: Selenium disulfide consists of 8-membered rings. Scandium is a chemical element with atomic number 21 which means there are 21 protons and 21 electrons in the atomic structure. Gold is a transition metal and a group 11 element. The chemical symbol for Thallium is Tl. Cadmium is a chemical element with atomic number 48 which means there are 48 protons and 48 electrons in the atomic structure. Selenous acid is bubbled with sulfur dioxide (reduction step) to give elemental selenium. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, and also has similarities to arsenic.

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