Platinum has the chemical symbol Pt and atomic number 78. It’s a dense, malleable, ductile, highly unreactive, precious, grey-white transition metal. Its name is derived from the Spanish term platina, which is literally translated into “little silver”.
Platinum occurs in the wild as the pure element as well as alloyed with iridium, known as platiniridium. It is one of the rarest elements in the Earth’s crust with an average abundance of approximately 5 μg/kg.
In addition to its high density, resistance to oxidation and other desirable qualities, platinum is remarkably chemically unreactive. For these reasons, a 90-10% alloy of platinum-iridium is still used as the International Prototype Kilogram. Originally, this prototype kilogram was made of pure platinum, but iridium was added to increase its hardness while retaining platinum’s many desirable qualities.
Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, and jewellery. Being a heavy metal, it leads to health issues upon exposure to its salts, but due to its corrosion resistance, it is not as toxic as some metals. Some compounds containing platinum are applied in chemotherapy against certain types of cancer.
Platinum;s resistance to wear and tarnish is well suited to its use in fine jewellery.
Platinum is obtained commercially as a by-product from nickel and copper mining and processing. As an example, of the 245 tonnes of platinum sold in 2010, 113 tonnes were used for vehicle emissions control devices (46%), 76 tonnes for jewellery (31%). The remaining 35.5 tonnes went to various other minor applications, such as investment, electrodes, anticancer drugs, oxygen sensors, spark plugs and turbine engines.
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