(So named (Greek osme, odor) in 1804 by S. Tennant, English chemist because of the odor of one of its oxides) A very hard, bluish-white, amorphous, metallic chemical element, one of the platinum metals. It occurs in the form of an alloy with platinum and iridium and is used in pen points, electric light filaments, etc. and as a catalyst.

Symbol: Os
Atomic number: 76
Atomic weight: 190.23
Density (at room temperature and pressure): 22.59 g/cc
Melting point: 3,000°C
Boiling point: 5,000°C
Valence: +3, +4
Ground state electron configuration: [Xe]4f¹⁴5d⁶6s²

Osmium
Symbol: Os
Atomic Number: 76
Atomic Weight: 190.23
Boiling Point: 5300 K
Melting Point: 3300 K
Density at 300K: 22.6 g/cm³
Covalent radius: 1.26
Atomic radius: 1.92
Atomic volume: 8.43 cm³/mol
First ionization potental: 8.7 V
Specific heat capacity: 0.13 Jg^-1K^-1
Thermal conductivity: 87.6 Wm^-1K^-1
Electrical conductivity: 12.3*10⁶Ω^-1m^-1
Heat of fusion: 29.29 kJ/mol
Heat of vaporization: 627.6 kJ/mol
Electronegativity: 2.2 (Pauling's)

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Os"mi*um (?), n. [Gr. a smell, odor, akin to to smell. So named in allusion to the strong chlorinelike odor of osmic tetroxide. See Odor.] Chem.

A rare metallic element of the platinum group, found native as an alloy in platinum ore, and in iridosmine. It is a hard, infusible, bluish or grayish white metal, and the heaviest substance known. Its tetroxide is used in histological experiments to stain tissues. Symbol Os. Atomic weight 191.1. Specific gravity 22.477.

 

© Webster 1913.