Relative atomic mass: 190.23 +- 0.03

English: Osmium
French: Osmium
Croatian: Osmij
German: Osmium
Italian: Osmio
Spanish: Osmio

Atomic number: 76
Group numbers: 8
Period: 6
Standard state (20 oC): solid

Discovery: 1803 Smithson Tennant (GB)
Osmium was discovered by Smithson Tennant (GB) in 1803. The origin of the name comes from the Greek word osme meaning smell. It is a hard fine black powder or hard, lustrous, blue-white metal. Osmium is unaffected by air, water and acids. It has a characteristic acrid, chlorine like odour due to tetroxide compound. Osmium tetroxide is highly toxic. Osmium is obtained from the same ores as platinum. It is used to tip gold pen points, instrument pivots, to make electric light filaments, and also used for high temperature alloys and pressure bearings. Osmium is very hard and resists corrosion better than any other element. The price of 99.95 % pure osmium powder is 2159.60 for 25 g.
Electronic configuration: [Xe] 4f14 5d6 6s2
Formal oxidation number: +3 +4
Atomic radius: 133.8 pm

Electronegativities: 2.2
Thermal conductivity: 87.6 W/(m K)
Electrical resistivity (20 oC): 9.5 microOhm cm

Melting point: 3033 oC
Boiling point: 5012 oC

Heat of fusion: 29.3 kJ/mol
Heat of vaporization: 738.06 kJ/mol
Heat of atomization: 791 kJ/mol

75Re <= 76Os => 77Ir

ASCII Periodic Table of the Elements
29 Aug. 2017
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