plat·i·num /ˈplætnəm, ˈplætṇəm/
 白金,鉑


 plat·i·num /ˈplætnəm, ṇəm/ 名詞
 鉑


 Plat·i·num n.  Chem. A metallic element of atomic number 78, one of the noble metals, classed with silver and gold as a precious metal, occurring native or alloyed with other metals and also as the platinum arsenide (sperrylite). It is a heavy tin-white metal which is ductile and malleable, but very infusible (melting point 1772° C), and characterized by its resistance to strong chemical reagents. It is used for crucibles in laboratory operations, as a catalyst, in jewelry, 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 195.1.  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.

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 platinum
      n : 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]


 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.