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Technetium Compounds
Technetium compounds are chemical compounds containing the chemical element technetium. Technetium can form multiple oxidation states, but often forms in the +4 and +7 oxidation states. Because technetium is radioactive, technetium compounds are extremely rare on Earth. Pertechnetate and derivatives The most prevalent form of technetium that is easily accessible is sodium pertechnetate, Na cO4 The majority of this material is produced by radioactive decay from 99MoO4.html" ;"title="sup>99MoO4">sup>99MoO4sup>2−: : 99MoO4.html" ;"title="sup>99MoO4">sup>99MoO4sup>2− → 99mTcO4.html" ;"title="sup>99mTcO4">sup>99mTcO4sup>− + e− Pertechnetate (tetroxidotechnetate) behaves analogously to perchlorate, both of which are tetrahedral. Unlike permanganate (), it is only a weak oxidizing agent. Related to pertechnetate is technetium heptoxide. This pale-yellow, volatile solid is produced by oxidation of Tc metal and related precursors: :4 Tc + 7 O2 → 2 Tc2O7 It is a molecul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Element
A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species. Unlike chemical compounds, chemical elements cannot be broken down into simpler substances by any chemical reaction. The number of protons in the nucleus is the defining property of an element, and is referred to as its atomic number (represented by the symbol ''Z'') – all atoms with the same atomic number are atoms of the same element. Almost all of the baryonic matter of the universe is composed of chemical elements (among rare exceptions are neutron stars). When different elements undergo chemical reactions, atoms are rearranged into new compounds held together by chemical bonds. Only a minority of elements, such as silver and gold, are found uncombined as relatively pure native element minerals. Nearly all other naturally occurring elements occur in the Earth as compounds or mixtures. Air is primarily a mixture o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telluride (chemistry)
The telluride ion is the anion Te2− and its derivatives. It is analogous to the other chalcogenide anions, the lighter O2−, S2−, and Se2−, and the heavier Po2−. In principle, Te2− is formed by the two-e− reduction of tellurium. The redox potential is −1.14 V. :Te(s) + 2 e− ↔ Te2− Although solutions of the telluride dianion have not been reported, soluble salts of bitelluride (TeH−) are known. Organic tellurides ''Tellurides'' also describe a class of organotellurium compounds formally derived from Te2−. An illustrative member is dimethyl telluride, which results from the methylation of telluride salts: :2 CH3I + Na2Te → (CH3)2Te + 2 NaI Dimethyl telluride is formed by the body when tellurium is ingested. Such compounds are often called telluroethers because they are structurally related to ethers with tellurium replacing oxygen, although the length of the C–Te bond is much longer than a C–O bond. C–Te–C angles tend to be close ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Technetium Trichloride
Technetium trichloride is an inorganic compound of technetium and chlorine with the formula TcCl3. Preparation and properties Two polymorphs of technetium trichloride are known. The α-polymorph is prepared as a black solid from ditechnetium(III) tetraacetate dichloride and hydrogen chloride at 300 °C. It has a bioctahedral structure, consisting of triangular Tc3Cl9 units with ''C''3v symmetry, with each Tc atom coordinated to two Tc neighbors and five chloride ligands (Tc-Tc bond length 2.44 angstrom The angstromEntry "angstrom" in the Oxford online dictionary. Retrieved on 2019-03-02 from https://en.oxforddictionaries.com/definition/angstrom.Entry "angstrom" in the Merriam-Webster online dictionary. Retrieved on 2019-03-02 from https://www.m ...). The Tc-Tc distances are indicative of double bonded Tc atoms. Tc3Cl9 is isostructural to its rhenium homologue, trirhenium nonachloride. β-TcCl3 is obtained by the reaction between technetium metal and chlorine gas. Its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platinum
Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish , a diminutive of "silver". Platinum is a member of the platinum group of elements and group 10 of the periodic table of elements. It has six naturally occurring isotopes. It is one of the rarer elements in Earth's crust, with an average abundance of approximately 5 μg/kg. It occurs in some nickel and copper ores along with some native deposits, mostly in South Africa, which accounts for ~80% of the world production. Because of its scarcity in Earth's crust, only a few hundred tonnes are produced annually, and given its important uses, it is highly valuable and is a major precious metal commodity. Platinum is one of the least reactive metals. It has remarkable resistance to corrosion, even at high temperatures, and is therefore considered a noble metal. Consequent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hafnium
Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1923, by Dirk Coster and George de Hevesy, making it the penultimate stable element to be discovered (the last being rhenium in 1925). Hafnium is named after , the Latin name for Copenhagen, where it was discovered. Hafnium is used in filaments and electrodes. Some semiconductor fabrication processes use its oxide for integrated circuits at 45 nanometers and smaller feature lengths. Some superalloys used for special applications contain hafnium in combination with niobium, titanium, or tungsten. Hafnium's large neutron capture cross section makes it a good material for neutron absorption in control rods in nuclear power plants, but at the same time requires that it be removed from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zirconium
Zirconium is a chemical element with the symbol Zr and atomic number 40. The name ''zirconium'' is taken from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian '' zargun'' (zircon; ''zar-gun'', "gold-like" or "as gold"). It is a lustrous, grey-white, strong transition metal that closely resembles hafnium and, to a lesser extent, titanium. Zirconium is mainly used as a refractory and opacifier, although small amounts are used 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, four of which are stable. Zirconium compounds have no known biological role. Characteristics Zirconium is a lustrous, greyish-white, soft, ductile, malleable metal that is solid at room temperature, though it is hard and brittle at lesser purities. In powder form, zirconium is highl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidation State
In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. Conceptually, the oxidation state may be positive, negative or zero. While fully ionic bonds are not found in nature, many bonds exhibit strong ionicity, making oxidation state a useful predictor of charge. The oxidation state of an atom does not represent the "real" formal charge on that atom, or any other actual atomic property. This is particularly true of high oxidation states, where the ionization energy required to produce a multiply positive ion is far greater than the energies available in chemical reactions. Additionally, the oxidation states of atoms in a given compound may vary depending on the choice of electronegativity scale used in their calculation. Thus, the oxidation state of an atom in a compound is purely a formalism. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TcCl4
Technetium(IV) chloride is the inorganic compound with the formula TcCl4. It was discovered in 1957 as the first binary halide of technetium. It is the highest oxidation binary chloride of technetium that has been isolated as a solid. It is volatile at elevated temperatures and its volatility has been used for separating technetium from other metal chlorides. Colloidal solutions of technetium(IV) chloride are oxidized to form Tc(VII) ions when exposed to gamma rays. Technetium tetrachloride can be synthesized from the reaction of Cl2 with technetium metal at elevated temperatures between 300 and 500 °C: :Tc + 2 Cl2 → TcCl4 Technetium tetrachloride has also been prepared from the reaction of technetium(VII) oxide with carbon tetrachloride in a sealed vessel at elevated temperature: :Tc2O7 + 7 CCl4 → 2 TcCl4 + 7 COCl2 + 3 Cl2 At 450 °C under vacuum, TcCl4 decomposes to TcCl3 and TcCl2. As verified by X-ray crystallography X-ray crystallography is the exper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TcF6
Technetium hexafluoride or technetium(VI) fluoride ( Tc F6) is a yellow inorganic compound with a low melting point. It was first identified in 1961. In this compound, technetium has an oxidation state of +6, the highest oxidation state found in the technetium halides. In this respect, technetium differs from rhenium, which forms a heptafluoride, ReF7. Technetium hexafluoride occurs as an impurity in uranium hexafluoride, as technetium is a fission product of uranium (spontaneous fission in natural uranium, possible contamination from induced fission inside the reactor in reprocessed uranium). The fact that the boiling point of the hexafluorides of uranium and technetium are very close to each other presents a problem in using fluoride volatility in nuclear reprocessing. Preparation Technetium hexafluoride is prepared by heating technetium metal with an excess of F2 at 400 °C. :Tc + 3 → Description Technetium hexafluoride is a golden-yellow solid at room temperatu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Nonahydridorhenate
Potassium nonahydridorhenate(VII) is an inorganic compound having the formula K2ReH9. This colourless salt is soluble in water but only poorly soluble in most alcohols. The anion is a rare example of a coordination complex bearing only hydride ligands. History The study of rhenium hydrides can be traced to the 1950s and included reports of the "rhenide" anion, supposedly Re−. These reports led to a series of investigations by A. P. Ginsberg and coworkers on the products from the reduction of perrhenate. The ''rhenide'' anion, Re−, was based on the product of the reduction of perrhenate salts, such as the reduction of potassium perrhenate () by potassium metal. "Potassium rhenide" was shown to exist as a tetrahydrated complex, with the postulated chemical formula . This compound exhibits strongly reducing properties, and slowly yields hydrogen gas when dissolved in water. The lithium and thallous salts were also reported. Later research, however, indicates that the "rhen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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