CALCIUM

The calcium (of the Latin calx, calis, lime) is a chemical element, of symbol Ca and of atomic number 20.
It is a gray silver metal .El metal is hard enough. The calcium is an essential component of the leaves, bones, teeth and shells. The calcium is the most abundant fifth element in the bark of the land and represents more than 3 % of the bark.
One finds in the internal way of the organisms as Ion calcium or forming a part of other molecules; in some alive beings it is precipitated in the shape of internal or external skeleton.
It intervenes in the metabolism of the glucógeno, close to the potassium and the sodium they regulate the muscular contraction. The percentage of calcium in the organisms is variable and depends on the species, for average term it represents 2,45 % in the set of the alive beings; in the vegetables, only it represents 0,007 %.
The calcium was discovered in 1808 by Humphry Davy by means of electrolysis of an amalgam of mercury and lime .Davy mixed lime moistened with oxide of mercury that he placed on a sheet of platinum, the anode, and plunged a part of mercury inside the pasta that it was doing of cathode; for electrolysis it obtained an amalgam that, revealed, left a solid residue very oxidable; later Bunsen in 1854 and Matthiessen in 1856 obtained the metal for electrolysis of the chloride of calcium and Henri Moissan obtained calcium with a purity of 99 % for electrolysis of the iodide. Until beginning of the 20th century the calcium only was obtained in laboratory.
Information extracted of: www.wikipedia.com and www.webelements.com