Calcium
Caclium is the twentieth element on the periodic table, and the third of the alkaline
earth metals. Its atomic mass is 40.078 amu, and its density is only 1.55 g/cm cubed.
Its electron levels are 2-8-8-2, and as do all of the alkaline earths, has a valence
of +2. Ca was discovered in 1878 by Sir Humphry Davy of England. Ca melts at 838.85
degrees C, and boils at 1483.85 degrees C. Calcium is the most common metal in the human body,
making up about 2% of our total mass. Pure Ca has been prepared by electrolyzing
calcium carbonate (chalk) in mercury. Calcium is the fifth most abundant metal in the earth's crust.
It is silvery and hard, readily reacts with water, and burns orange. It is alloyed
with aluminum, beryllium, copper, lead, and magnesium.
May 18, 1997
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