See Also: Platinum(medicine)
platinum(encyclopedia)
platinum(dictionary)
PLATINUM(finance)
platinum(dictionary)
Eastern Platinum(finance)
platinum blonde(dictionary)
platinum compounds(medicine)
platinum foil(medicine)
Southern Platinum(finance)

platinum (sh)




Metallic chemical element, one of the transition elements, chemical symbol Pt, atomic number 78.

A very heavy, silvery white precious metal, it is soft and ductile, with a high melting point (3,216 ¡ãF [1,769 ¡ãC]) and good resistance to corrosion and chemical attack. Small amounts of iridium are commonly added for a harder, stronger alloy that retains platinum's advantages. Platinum is found usually as alloys of 80-90% purity in placer deposits or more rarely combined with arsenic or sulfur. It is indispensable in high-temperature laboratory work for electrodes, dishes, and electrical contacts that resist chemical attack even when very hot. Platinum is used in dental alloys and surgical pins; alloys typically containing 90-95% platinum are used in expensive jewelry. The international primary standard for the kilogram is made of 90% platinum, 10% iridium. Platinum has valence 2 or 4 in its compounds, which include many coordination complexes. It and some compounds are useful catalysts, particularly for hydrogenation and in catalytic converters for reducing automobile emissions.