Atomic number:76

Group numbers:8

Period:6

Electronic configuration:[Xe] 4f¹⁴ 5d⁶ 6s²

Formal oxidation number:+3 +4

Electronegativities:2.2

Atomic radius / pm:133.8

Relative atomic mass:190.23 ± 0.03

 

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.

Density / g dm^-3:22590 (293 K)

 20100 (m.p.)

Molar volume / cm³mol^-1:8.42 (293 K)

 9.46 (m.p.)

Electrical resistivity / μΩcm:9.5 (20 °C)

Thermal conductivity / W m^-1K^-1:87.6

Melting point / °C:3033

Boiling point / °C:5012

Heat of fusion / kJ mol^-1:29.3

Heat of vaporization / kJ mol^-1:738.06

Heat of atomization / kJ mol^-1:791

1st ionization energy / kJ mol^-1:814.17

2nd ionization energy / kJ mol^-1:-

3rd ionization energy / kJ mol^-1:-

in the atmosphere / ppm:-

in the Earth's crust / ppm:0.005

in the oceans / ppm:-