Iridium

Source of the photo
http://commons.wikimedia.org/wiki/File:Electron_shell_077_iridium.png
Author of the description
Gruiz Katalin

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.