osmium


Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.
Related to osmium: osmium tetroxide

osmium

(ŏz`mēəm), metallic chemical element; symbol Os; at. no. 76; at. wt. 190.23; m.p. 3,045±30°C;; b.p. 5,027±100°C;; sp. gr. 22.57 at 20°C;; valence usually +0 to +8. Osmium is a very hard, brittle, lustrous bluish-white metal with a close-packed hexagonal crystalline structure. It immediately precedes iridium in Group 8 of the periodic tableperiodic table,
chart of the elements arranged according to the periodic law discovered by Dmitri I. Mendeleev and revised by Henry G. J. Moseley. In the periodic table the elements are arranged in columns and rows according to increasing atomic number (see the table entitled
..... Click the link for more information.
. The measured densities of osmium and iridium indicate that osmium is slightly more dense than iridium, and osmium is generally credited as the heaviest element. Osmium does not oxidize readily in air except when heated or in powdered form; it then forms the unpleasant smelling, highly toxic tetroxide, OsO4. The tetroxide is used in microscopy as a stain, in fingerprint detection, and as a catalyst. Osmium is not affected by common acids but is oxidized to the tetroxide by hot nitric acid, hot sulfuric acid, or aqua regia. Osmium reacts with fluorine or chlorine gas at high temperatures to give the tetrafluoride or tetrachloride. In addition to the valences noted above, osmium assumes other valences between 0 and +8 in various compounds. Osmium is found in platinum ores and in the mineral osmiridium. It is recovered commercially as a byproduct of the refining of nickel ores mined near Sudbury, Ont., Canada. The metal is used largely for the production of hard alloys for use in fountain pen points, phonograph needles, and instrument bearings. Osmium was discovered by Smithson Tennant in 1804 in a residue left after dissolving crude platinum in aqua regia.

Osmium

 

Os, a chemical element in group VIII of the Mendeleev periodic system. Atomic number, 76; atomic weight, 190.2. One of the platinum metals.

osmium

[′äz·mē·əm]
(chemistry)
A chemical element, symbol Os, atomic number 76, atomic weight 190.2.
(metallurgy)
A hard white metal of rare natural occurrence.

osmium

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
References in periodicals archive ?
Ramon, "Osmium impregnated on magnetite as a heterogeneous catalyst for the syndihydroxylation of alkenes," Applied Catalysis A: General, vol.
Andy Oppenheimer, a nuclear, biological and chemical weapons expert for Jane's Information Group, said osmium tetroxide was an unusual choice as a chemical weapon but it could kill.
Andy Oppenheimer, a nuclear,biological and chemical weapons expert for Jane's InformationGroup, said osmium tetroxide was an unusual choice of chemical but it could kill.
Suspects' conversations were eavesdropped on at the GCHQ electronic listening centre and police moved to disrupt the plot at an early stage before any osmium tetroxide was obtained.
According to Webster's New World Dictionary of Science (1998, Helicon), osmium's discoverer, Smithson Tennant, named the element "after the irritating smell of one of its oxides."--P.
A volatile form of osmium is generated during platinum refinement and also during the normal operation of cars, and it gets dispersed globally through the atmosphere.
In a surprising overturn, the lustrous, blue-white element osmium has beaten diamond in a test of compressibility.
Washington, Dec 9 (ANI): Researchers at University of Warwick say that a precious metal called osmium, which has never been used in a clinical setting before, may lead to next generation of improved cancer treatments.
Certain metals, such as osmium, would have been pulled into Earth's central core if they had been present before the planet got wet.
Suspecting that hassium has properties similar to osmium and other so-called group 8 elements, chemists placed hassium on the periodic table directly below osmium.
Smotkin then tested the most promising ones in fuel cells and found that a particular blend of platinum, ruthenium, osmium, and iridium is much more active than the platinum-ruthenium alloy now considered the best catalyst available.
They reacted a 50-50 mixture of carbon-76 molecules with an osmium compound and a plant alkaloid that preferentially grabs one version of the molecule (SN: 1/2/93, p.6).