Precious Metal Elements

Iridium[   Atomic number77   Atomic weight192.217   ]

Used for vehicle spark plugs because of excellent hardness and corrosion resistance, and for the crucibles used to manufacture sapphire substrates for LEDs because of high heat resistance.

Ir Iridium
Atomic number 77
Atomic weight 192.217
Isotope 191Ir, 193Ir
Crystal Structure fcc
Metallicity Trans.Metal
Shell 2,8,18,32,15,2
Filling Orbital 5d7
Oxidation States 2,3,4,6
Atomic Radius Å 1.87
Covalent Radius Å 1.36
Atomic Volume cm3/mol 8.54
Density at 293K g/cm3 22.42
Melting Point 2443
Boiling Point 4437
Specific Heat J/gK 0.130
Heat of Fusion kJ/mol 26.10
Heat of Vaporization kJ/mol 604.0
Thermal Conductivity at 273K W/cmK 1.47
Specific Resistance at 273K 10-6 Ωcm 4.7
Coefficient of Linear expansion at 293K 10-6 K-1 6.4
Ionization Potential V 8.96702
2nd Ionization Potential V
Electron Affinity eV 1.5638
Electronegativity 2.2
Discovery year 1804