cadmiumCdchemical element, metal of Group IIb, or the zinc group, of the periodic table.
Properties, occurrence, and uses



Most cadmium produced is electroplated onto steel, iron, copper, brass, and other alloys to protect them from corrosion. Cadmium plating is especially resistant to attack by alkali. Some is used as the anode material in rechargeable storage batteries in which the oxide of nickel or silver is the cathode. Cadmium unites combines with many heavy metals to yield alloys; the most important are bearing alloys and low-melting alloys used for soldering and brazing. Because it efficiently absorbs thermal neutrons, it is used in control rods for some nuclear reactors.

Natural cadmium is a mixture of eight isotopes: 106Cd (1.2 percent), 108Cd (0.9 percent), 110Cd (12.4 percent), 111Cd (12.8 percent), 112Cd (24.0 percent), 113Cd (12.3 percent), 114Cd (28.8 percent), and 116Cd (7.6 percent).


In its compounds cadmium exhibits almost exclusively the +2 oxidation state, as in the colourless Cd2+ ion, which forms a number of stable complex ions, especially halide complexes. A few compounds of the +1 oxidation state have been prepared by dissolving cadmium metal in molten doubly charged cadmium (IICd2+) halides. The resultant diatomic cadmium (I) ion, Cd22+ (where cadmium is in the +1 oxidation state), is unstable in water and immediately disproportionates to cadmium metal and Cd2+.


atomic number48atomic weight112.40melting point321° C (610° F)boiling point765° C (1,409° F)specific gravity8.65 (20° C, 68° F)valence2electronic configuration2-8-18-18-2 or (Kr)oxidation state+2electronic configuration[Kr]4d105s2