Atomic number | 77 |
Atomic mass | 192.2 g.mol -1 |
Electronegativity | 2.2 |
Density | 22.4 g.cm-3 at 20°C |
Melting point | 2450 °C |
Boiling point | 4527 °C |
Vanderwaals radius | 0.126 nm |
Ionic radius | 0.066 nm (+4) |
Isotopes | 11 |
Electronic shell | [ Xe ] 4f14 5d7 6s2 |
Energy of first ionisation | 886 kJ.mol -1 |
Standard potential | + 1.0 V ( Ir2+/ Ir ) |
Discovered by | Smithson Tennant in 1804 |
Iridium is a hard, brittle, lustrous, dense, transition metal of the platinum family. It is silvery-white and it is notable for being the most corrosion resistant element known. It is unaffected by air, water and acids.
Applications
Nowadays demand for iridium comes mainly from the electronic industry, the automotive industry and from the chemical industry, where it is used to coat the electrodes in the chlor-alkali process, and in catalyst.
Some applications are in pivot bearings and in scientific and other special equipment, but it is principally used in alloys: osmium/iridium alloys are used for tipping fountain pen nibs and for compass bearings.