Calcium
For cement and plaster of paris.
Atomic Number: 20
Atomic Symbol: Ca
Atomic Weight: 40.08
Electron Configuration:[Ar]4s^2History
(L. calx, lime) Though lime was prepared by the Romans in the first century under the name
calx, the metal was not discovered until 1808. After learning that Berzelius and Pontin prepared
calcium amalgam by electrolyzing lime in mercury, Davy was able to isolate the impure metal.
Sources
Calcium is a metallic element, fifth in abundance in the earth's crust, of which if forms more than
3%. It is an essential constituent of leaves, bones, teeth, and shells. Never found in nature
uncombined, it occurs abundantly as limestone, gypsum, and fluorite. Apatite is the
fluorophosphate or chlorophosphate of calcium.
Properties
The metal has a silvery color, is rather hard, and is prepared by electrolysis of the fused chloride
to which calcium fluoride is added to lower the melting point.
Chemically it is one of the alkaline earth elements; it readily forms a white coating of nitride in
air, reacts with water, burns with a yellow-red flame, forming largely the nitride.
Uses
The metal is used as a reducing agent in preparing other metals such as thorium, uranium,
zirconium, etc., and is used as a deoxidizer, desulfurizer, or decarburizer for various ferrous and
nonferrous alloys. It is also used as an alloying agent for aluminum, beryllium, copper, lead, and
magnesium alloys, and serves as a "getter" for residual gases in vacuum tubes, etc.
Calcium