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

SymbolIr
Atomic number77
Group9
Period6
Blockd
Element categoryTransition Metal

Physical properties

Phase at STPSolid
Density22.56 g/cm3
Atomic weight192.217 u
Melting point2719 K
2445.85 °C
4434.53 °F
Boiling point4403 K
4129.85 °C
7465.73 °F

Atomära egenskaper

Electronegativity (Pauling Scale)2.2
Electron affinity150.94 kJ/mol
Ionization energies
1880 kJ/mol
2 1600 kJ/mol

Electron configuration

Electron configuration1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d7 6s2
Electrons per shell2, 8, 18, 32, 15, 2

History

Discovered1803
Discovered bySmithson Tennant