Palladium

Palladium is a chemical element with symbol Pd and atomic number 46. It is named after the asteroid Pallas. Palladium is a soft silver-white metal that resembles platinum. It is the least dense and has the lowest melting point of the platinum group metals. It is soft and ductile when annealed and greatly increases its strength and hardness when it is cold-worked. Palladium dissolves slowly in concentrated nitric acid, in hot, concentrated sulfuric acid, and, when finely divided, in hydrochloric acid.

Naturally occurring palladium is composed of seven isotopes, which includes six stable isotopes.

Palladium does not react with oxygen at normal temperatures. Palladium heated to 800 °C will produce a layer of palladium(II) oxide (PdO). It tarnishes lightly in a moist atmosphere containing sulfur.

The main use for palladium by the Union is in full-weight coin.