Platinum : (noun)
1: a heavy precious metallic element; gray-white and resistant
to corroding; occurs in some nickel and copper ores and
is also found native in some deposits [syn: Pt, atomic
number 78]
Based on WordNet 2.0
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Platinum : \Plat"i*num\, n. [NL., fr. Sp. platina, from plata
silver, LL. plata a thin plate of metal. See Plate, and cf.
Platina.] (Chem.)
A metallic element, intermediate in value between silver and
gold, occurring native or alloyed with other metals, also as
the platinum arsenide (sperrylite). It is heavy tin-white
metal which is ductile and malleable, but very infusible, and
characterized by its resistance to strong chemical reagents.
It is used for crucibles, for stills for sulphuric acid,
rarely for coin, and in the form of foil and wire for many
purposes. Specific gravity 21.5. Atomic weight 194.3. Symbol
Pt. Formerly called platina.
Platinum black (Chem.), a soft, dull black powder,
consisting of finely divided metallic platinum obtained by
reduction and precipitation from its solutions. It absorbs
oxygen to a high degree, and is employed as an oxidizer.
Platinum lamp (Elec.), a kind of incandescent lamp of which
the luminous medium is platinum. See under Incandescent.
Platinum metals (Chem.), the group of metallic elements
which in their chemical and physical properties resemble
platinum. These consist of the light platinum group, viz.,
rhodium, ruthenium, and palladium, whose specific
gravities are about 12; and the heavy platinum group,
viz., osmium, iridium, and platinum, whose specific
gravities are over 21.
Platinum sponge (Chem.), metallic platinum in a gray,
porous, spongy form, obtained by reducing the double
chloride of platinum and ammonium. It absorbs oxygen,
hydrogen, and certain other gases, to a high degree, and
is employed as an agent in oxidizing.
Based on Webster's Revised Unabridged Dictionary
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Platinum, AK (city, FIPS 61080)
Location: 58.97394 N, 161.72523 W
Population (1990): 64 (45 housing units)
Area: 115.4 sq km (land), 0.0 sq km (water)
Zip code(s): 99651
Based on U.S. Gazetteer (1990) [Census_Database]:
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Platinum : Symbol: Pt
Atomic number: 78
Atomic weight: 195.078
Attractive greyish-white metal. When pure, it is malleable and ductile.
Does not oxidize in air, insoluble in hydrochloric and nitric acid.
Corroded by halogens, cyandies, sulphur and alkalis. Hydrogen and
oxygen react explosively in the presence of platinum. There are six
stable isotopes and three radioisotopes, the most stable being Pt-193
with a half-life of 60 years. Platinum is used in jewelry, laboratory
equipment, electrical contacts, dentistry, and anti-pollution devices in
cars. PtCl2(NH3)2 is used to treat some forms of cancer. Platinum-{cobalt
alloys have magnetic properties. It is also used in the definition of
the Standard Hydrogen Electrode. Discovered by Antonio de Ulloa in South
America in 1735. The name comes from the Spanish word platina which means
silver. Platinum metal is generally not a health concern due to its
unreactivity, however platinum compounds should be considered highly
toxic.
Based on U.S. Gazetteer (1990) [Census_Database]:
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