osmium

[oz-mee-uhm]
noun Chemistry.
a hard, heavy, metallic element having the greatest density of the known elements and forming octavalent compounds, as OsO 4 and OsF 8 : 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.

Origin:
1795–1805; < Neo-Latin < Greek osm() smell + -ium -ium; named from the penetrating odor of one of its oxides

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World English Dictionary
osmium (ˈɒzmɪəm)
 
n
a very hard brittle bluish-white metal occurring with platinum and alloyed with iridium in osmiridium: used to produce platinum alloys, mainly for pen tips and instrument pivots, as a catalyst, and in electric-light filaments. Symbol: Os; atomic no: 76; atomic wt: 190.2; valency: 0 to 8; relative density: 22.57; melting pt: 3033±30°C; boiling pt: 5012±100°C
 
[C19: from Greek osmē smell, so called from its penetrating odour]

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Word Origin & History

osmium
metallic element, 1803, coined in Mod.L. by its discoverer, Eng. chemist Smithson Tennant (1761-1815) from Gk. osme "smell, odor" (cognate with L. odor, see odor). So called for the strong smell of its oxide.
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Medical Dictionary

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.

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Science Dictionary
osmium   (ŏz'mē-əm)  Pronunciation Key 
Symbol Os
A hard, brittle, bluish-white metallic element that is the densest naturally occurring element. It is used to make very hard alloys for fountain pen points, electrical contacts, 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 Periodic Table.
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Encyclopedia Britannica
Encyclopedia

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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Example sentences
Two elements sometimes found inside gold, rhenium and osmium, help serve as a radioactive clock.
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