[oz-mee-uh
m] 
| a hard, heavy, metallic element having the greatest density of the known elements and forming octavalent compounds, as OsO4 and OsF8: used chiefly as a catalyst, in alloys, and in the manufacture of electric-light filaments. Symbol: Os; atomic weight: 190.2; atomic number: 76; specific gravity: 22.57. |
) smell + -ium -ium; named from the penetrating odor of one of its oxides| os·mi·um (ŏz'mē-əm) n. Symbol Os A bluish-white, hard metallic element, found in small amounts in osmiridium, nickel, and platinum ores. It is used as a platinum hardener and in making pen points, phonograph needles, and instrument pivots. Atomic number 76; atomic weight 190.2; melting point 3,000°C; boiling point 5,000°C; specific gravity 22.57; valence 2, 3, 4, 8. See Table at element. [From Greek osmē, smell (from the strong odor of osmium tetroxide).] |
osmium os·mi·um (ŏz'mē-əm)
n.
Symbol Os
A hard metallic element, found in small amounts in osmiridium and platinum ores. Atomic number 76; atomic weight 190.2; melting point 3,000°C; boiling point 5,000°C; specific gravity 22.57; valence 3, 4, 6, 8.
osmium
((Os), chemical element, one of the platinum metals of Group VIIIb of the periodic table and the densest naturally occurring element. A gray-white metal, osmium is very hard, brittle, and difficult to work, even at high temperatures. Of the platinum metals it has the highest melting point, so fusing and casting are difficult. Osmium wires were used for filaments of early incandescent lamps before the introduction of tungsten. It has been used chiefly as a hardener in alloys of the platinum metals, though ruthenium has generally replaced it. A hard alloy of osmium and iridium has been used for tips of fountain pens and phonograph needles, and osmium tetroxide is used in certain organic syntheses.
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