Palladium (element)
Palladium, a soft, white, metallic element belonging to the platinum group of metals. It does not tarnish or corrode in air, but it is dissolved by aqua regia and by sulfuric acid. The metal can absorb 900 times its volume of hydrogen.
Palladium is used as a catalyst and in alloys that are used in jewelry, in dental work, and in electrical contacts for telephones. Palladium was discovered in 1803 by W. H. Wollaston in England, and named after the asteroid Pallas.
Symbol: Pd. Atomic number: 46. Atomic weight: 106.42. Specific gravity: 12.0. Melting point: 2,826 F. (1,552 C.). Boiling point: 5,684 F. (3,140 C.). It has six stable isotopes. It belongs to Group VIII of the Periodic Table. Valences: +2, 3, 4.