Palladium ( Pd )
Discovered in 1803 by W.H. Woollaston-England.
Palladium has a melting point of 1554°C, boiling point of 2970°C, specific gravity of 12.02 (20°C), and valence of 2, 3, or 4. It is a steel-white metal which does not tarnish in air. Palladium has the lowest melting point and density of the platinum metals. Annealed palladium is soft and ductile, but it becomes much stronger and harder through coldworking.
Palladium can be beaten into leaf as thin as 1/250,000 of an inch. Palladium is used as an alloying agent and for making jewelry and in dentistry. White gold is an alloy of gold which has been decolorized by the addition of palladium. The metal is also used to make surgical instruments, electrical contacts, and watches.