Naturally occurring iridium is a mixture of two isotopes: 191Ir and 193Ir with natural abundances of 37.3% and 62.7% respectively. Isotopes: Iridium has 34 isotopes whose half-lives are known, with mass numbers from 165 to 198. Commercially, iridium is recovered as a by-product from the nickel mining industry. Source: Iridium is found in natural alloys with platinum and osmium in alluvial deposits. Radioactive isotopes of iridium are used in radiation therapy for the treatment of cancer.Ībundance earth’s crust: 0.4 parts per billion by weight, 0.05 parts per billion by molesĪbundance solar system: 2 parts per billion by weight, 0.01 parts per billion by moles Iridium is the most corrosion-resistant metal known Physical Properties Phase Solid Density 22.56 g/cm 3 Melting Point 2739.15 K 2466 C 4470.8 F Boiling Point 4701.15 K 4428 C 8002.4 F Heat of Fusion 26 kJ/mol Heat of Vaporization 560 kJ/mol Specific Heat Capacity 0. Iridium was used in making the international standard kilogram, which is an alloy of 90% platinum and 10% iridium. It is also used to make heavy-duty electrical contacts. Iridium is used in making crucibles and other equipment that is used at high temperatures. Iridium, symbol Ir, has a Face Centered Cubic structure and Silver. With osmium, it forms an alloy that is used for tipping pens, and compass bearings. Element 77 of Periodic table is Iridium with atomic number 77, atomic weight 192.217. The main use of iridium is as a hardening agent for platinum alloys. 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. Iridium is attacked by molten salts such as sodium chloride (NaCl) and sodium cyanide (NaCN). It is the most corrosion-resistant metal known and it resists attack by any acid. Iridium is a rare, hard, lustrous, brittle, very dense platinum-like metal. Iridium in powder form is a known irritant and is a fire hazard. Iridium is considered to be of low toxicity.
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