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Iridium metal4/3/2024 ![]() Copyright © 2024, Columbia University Press. The Columbia Electronic Encyclopedia, 6th ed. Iridium was discovered in 1804 by Smithson Tennant it is so named because of its various highly colored salts. It resists attack by fused bases and by most molten metals. It is oxidized slowly at high temperatures. The geometric shape selected for the iridium target pieces is dependent on its eventual use. Therefore, natural iridium metal, with its natural abundance of 37 191 Ir, is the target material for production of 192 Ir by the n, reaction in a nuclear reactor. ![]() Fluorine and chlorine attack it only at a red heat. Iridium metal is one of the most chemically inert materials in existence. Pure iridium metal is not attacked by acids or acid mixtures, not even by aqua regia, which dissolves gold. It is the most corrosion-resistant metal known, and was used in making the standard meter bar of Paris, which is a 90 percent platinum and 10 percent iridium alloy. Because iridium is very hard and brittle, it is hard to machine, form, or work. Formerly the international meter standard was the distance between two marks on a bar made of that same alloy it is now based on the wavelength of a line in the spectrum of an isotope of krypton. Iridium, a metal of the platinum family, is white (similar to platinum) but with a slight yellowish cast. Since iridium is less reactive, it is generally considered. An alloy of 10 parts iridium with 90 parts platinum is used in the international kilogram standard in Paris. Iridium and Osmium: Iridium is the only metal known to be corrosion resistant and resist extreme temperatures even up to 2000 ☌ 294. It is referred to as a transition metal and also as a platinum metal, along with ruthenium, rhodium, palladium, osmium, and platinum itself. On the periodic table of elements, it is found in Group 9, between platinum and osmium. Alloys with platinum are used in heavy-duty electrical contacts. Iridium is a metallic element with the atomic number 77 and the symbol Ir. An alloy with osmium is used to make fountain-pen nibs. It is also used in making chemical crucibles. A very hard, brittle, silvery-white transition metal of the platinum group, iridium is generally credited with being the second densest element (after osmium) based on measured density, although calculations involving the space lattices of the elements show that iridium is denser. The metal is used in pivot bearings and in scientific and other special equipment, such as surgical tools. Iridium is a chemical element with symbol Ir and atomic number 77. It is obtained commercially from osmiridium, a byproduct of platinum production. Iridium is found uncombined in nature as the metal and in combination with osmium and platinum. It is not certain whether osmium or iridium is the most dense element. It falls between platinum and osmium in Group 9 of the periodic table. Iridium is a very hard, usually brittle, extremely corrosion-resistant silver-white metal with a face-centered cubic crystalline structure. Iridium ĭrĭdˈēəm, metallic chemical element symbol Ir at.
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