Osmium Platinum

Iridium (Ir)

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

Symbol

Atomic number

Group

Period

Block

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

Atomära egenskaper

Electronegativity (Pauling Scale)

2.2

Electron affinity

150.94 kJ/mol

Ionization energies

1	880 kJ/mol
2	1600 kJ/mol

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