Palladium
n.
A rare metallic element of the light platinum group, found native, and also alloyed with platinum and gold. It is a silver-white metal resembling platinum, and like it permanent and untarnished in the air, but is more easily fusible, with a melting point of 1555° C. It can also be prepared as a finely divided black powder. It is unique in its power of absorbing hydrogen, which it does to the extent of nearly a thousand volumes, forming the alloy Pd2H . It is used for graduated circles and verniers, for plating certain silver goods, and somewhat in dentistry. It was so named in 1804 by Wollaston from the asteroid Pallas , which was discovered in 1802. Symbol Pd. Atomic number, 46. Atomic weight, 106.42. Density 12.0.
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