Platinum is a chemical element in the periodic table that has the symbol Pt and atomic number 78. Platinum is a heavy, malleable, ductile, precious, gray-white transition metal, and platinum is resistant to corrosion and occurs in some nickel and copper ores along with some native deposits. Platinum is used in jewelry, laboratory equipment, electrical contacts, dentistry, and automobile emissions control devices.
Platinum appears silvery-white when pure, and firm. Platinum is corrosion-resistant. The catalytic properties of the six platinum family metals are outstanding (a mixture of hydrogen and oxygen explodes in the presence of platinum). For this catalytic property platinum is used in catalytic converters, incorporated in automobile exhaust systems.
Platinum's wear- and tarnish-resistance characteristics are well suited for making fine jewelry. Platinum is more precious than gold. The price of platinum changes along with its availability, but it normally costs about twice as much as gold. In the 18th century, platinum's rarity made King Louis XV of France declare it the only metal fit for a king.
Other distinctive properties of platinum include resistance to chemical attack, excellent high-temperature characteristics, and stable electrical properties. All these properties of platinum have been exploited for industrial applications. Platinum does not oxidize in air at any temperature but can be corroded by cyanides, halogens, sulfur, and caustic alkalis. Platinum is insoluble in hydrochloric and nitric acid but does dissolve in the mixture known as aqua regia (forming chloroplatinic acid). Common oxidation states of platinum include +2, +3, and +4.