Relative atomic mass: 192.217 +- 0.003

English: Iridium
French: Iridium
Croatian: Iridij
German: Iridium
Italian: Iridio
Spanish: Iridio

Atomic number: 77
Group numbers: 9
Period: 6
Standard state (20 oC): solid

Discovery: 1803 Smithson Tennant (GB)
Iridium was discovered by Smithson Tennant (GB) in 1803. The origin of the name comes from the Latin word iris, meaning rainbow, because its salts are highly coloured. It is a heavy, brittle, white metal that is unreactive in air, water and acids but reacts with fused NaOH. Metal ignites and burns readily. Iridium is found in gravel deposits with platinum. It is used with osmium to tip gold pen points, to make crucible and special containers, also to make alloys used for standard weights and measures and heat-resistant alloys. It is used as a hardening agent for platinum. The price of 99.95 % pure iridium sponge is 829.60 for 10 g.
Electronic configuration: [Xe] 4f14 5d7 6s2
Formal oxidation number: +3 +4
Atomic radius: 135.7 pm

Electronegativities: 2.2
Thermal conductivity: 147 W/(m K)
Electrical resistivity (20 oC): 5.3 microOhm cm

Melting point: 2446 oC
Boiling point: 4428 oC

Heat of fusion: 26.4 kJ/mol
Heat of vaporization: 612.1 kJ/mol
Heat of atomization: 664.34 kJ/mol

76Os <= 77Ir => 78Pt

ASCII Periodic Table of the Elements
29 Aug. 2017
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