Palladium (Pd), chemical element, the least dense and lowest-melting of the platinum group metals

A precious gray-white metal, palladium is extremely ductile and easily worked. Palladium is not tarnished by the atmosphere at ordinary temperatures. Thus, the metal and its alloys serve as substitutes for platinum in jewelry and in electrical contacts; the beaten leaf is used for decorative purposes. Relatively small amounts of palladium alloyed with gold yield the best white gold. Palladium is used also in dental alloys. The chief use of palladium, however, is in automobile catalytic converters (often in combination with rhodium); the palladium serves as a catalyst to convert polluting hydrocarbons, carbon monoxide, and nitrogen oxide in the exhaust to water, carbon dioxide, and nitrogen. Palladium coatings, electrodeposited or chemically plated, have been used in printed-circuit components, and palladium is also used in multilayer ceramic capacitors.