Iridium Facts - Periodic Table of the Elements

Iridium Facts - Periodic Table of the Elements Iridium  Basic Facts Atomic Number: 77 Symbol: Ir Atomic Weight: 192.22 Discovery: S.Tenant, A.F.Fourcory, L.N.Vauquelin, H.V.Collet-Descoltils 1803/1804 (England/France) Electron Configuration: [Xe] 6s2 4f14 5d7 Word Origin: Latin iris rainbow, because the salts of iridium are highly colored Properties: Iridium has a melting point of 2410 °C, boiling point of 4130 °C, specific gravity of 22.42 (17 °C), and valence of 3 or 4. A member of the platinum family, iridium is white like platinum, but with a slight yellowish cast. The metal is very hard and brittle and is the most corrosion resistant metal known. Iridium is not attacked by acids or aqua regia, but it is attacked by molten salts, including NaCl and NaCN. Either iridium or osmium is the densest known element, but the data do not allow for selection between the two. Uses: The metal is used for hardening platinum. It is used in crucibles and other applications requiring high temperatures. Iridium is combined with osmium to form an alloy used in compass bearings and for tipping pens. Iridium is also used for electrical contacts and in the jewelry industry. Sources: Iridium occurs in nature uncombined or with platinum and other related metals in alluvial deposits. It is recovered as a by-product from the nickel mining industry. Element Classification: Transition Metal Iridium Physical Data Density (g/cc): 22.42 Melting Point (K): 2683 Boiling Point (K): 4403 Appearance: white, brittle metal Atomic Radius (pm): 136 Atomic Volume (cc/mol): 8.54 Covalent Radius (pm): 127 Ionic Radius: 68 (4e) Specific Heat (20 °C J/g mol): 0.133 Fusion Heat (kJ/mol): 27.61 Evaporation Heat (kJ/mol): 604 Debye Temperature (K): 430.00 Pauling Negativity Number: 2.20 First Ionizing Energy (kJ/mol): 868.1 Oxidation States: 6, 4, 3, 2, 1, 0, -1 Lattice Structure: Face-Centered Cubic Lattice Constant (Ã…): 3.840 References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Langes Handbook of Chemistry (1952), CRC Handbook of Chemistry Physics (18th Ed.) Return to the Periodic Table Chemistry Encyclopedia