From Wikipedia, the free encyclopediaIridium is a chemical element with symbol Ir and atomic number 77. 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. It is also the most corrosion-resistant metal, even at temperatures as high as 2000 °C. Although only certain molten salts and halogens are corrosive to solid iridium, finely divided iridium dust is much more reactive and can be flammable. | |||||
Iridium in the periodic table | |||||
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Symbol | Ir | ||||
Atomic number | 77 | ||||
Group | 9 | ||||
Period | 6 | ||||
Block | d | ||||
Element category | Transition Metal | ||||
Physical properties | |||||
Phase at STP | Solid | ||||
Density | 22.56 g/cm3 | ||||
Atomic weight | 192.217 u | ||||
Melting point | 2719 K 2445.85 °C 4434.53 °F | ||||
Boiling point | 4403 K 4129.85 °C 7465.73 °F | ||||
Atomic properties | |||||
Electronegativity (Pauling Scale) | 2.2 | ||||
Electron affinity | 150.94 kJ/mol | ||||
Oxidation states | −3, −1, 0, +1, +2, +3, +4, +5, +6, +7, +8, +9 () | ||||
Ionization energies |
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Electron configuration | |||||
Elektronkonfiguration (shorthand) | [Xe] 4f14 5d7 6s2 | ||||
Electron configuration | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d7 6s2 | ||||
Electrons per shell | 2, 8, 18, 32, 15, 2 | ||||
History | |||||
Discovered | 1803 | ||||
Discovered by | Smithson Tennant |