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Chemical elements
  Calcium
    Isotopes
    Energy
    Preparation
    Physical Properties
    Chemical Properties
    Glass
    Cement
    PDB 158d-1ajq
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    PDB 1byn-1c8q
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    PDB 1dav-1dva
    PDB 1dvi-1el1
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    PDB 1ia6-1iyi
    PDB 1iz7-1jc2
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    PDB 1jv2-1kck
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    PDB 1kvy-1led
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    PDB 3jq5-3kfy
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    PDB 3nju-3oiu
    PDB 3oiv-3p7w
    PDB 3p85-3qfe
    PDB 3qgm-4tf4
    PDB 4tli-830c
    PDB 8cgt-9rnt

Element Calcium, Ca, Alkaline Earth Metal

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About Calcium

The compounds of calcium have an exceedingly wide distribution in the earth's crust, and form one of the most abundant constituents of the latter. It is the carbonate chiefly that occurs in nature; in the silicates of the earth's crust, also, calcium is seldom absent. The element also takes part in the most varied way in the building up of the organisms.

Metallic calcium was comparatively late in being prepared in the pure condition. Davy and Berzelius, at the beginning of the nineteenth century, attempted to obtain it from the electrolytically prepared amalgam by distilling off the mercury, but they did not obtain a sufficiently pure material to allow of its properties being ascertained. At the present day, however, large quantities of calcium are prepared by the electrolysis of fused calcium chloride. Prepared in this way, or by the decomposition of calcium iodide with sodium (whereby, after removal of the excess of sodium, crystallised calcium is obtained, it is found that this element is a white (not, as previously stated, a yellow) metal of density 1.83 which can be remelted in a vacuum at 760°, and can then be cut; it is, however, not so soft as potassium. It is not affected by oxygen, chlorine, bromine, or iodine at the ordinary temperature, but combines with these only on being heated. When heated in the air, it burns, forming a compound both with the oxygen and the nitrogen. It is only slowly attacked by water, but quickly by dilute acids.

Calcium Occurrence

Calcium, always in the combined form, is among the more widely distributed and the more abundant of the elements. It is an important constituent of many rocks, both igneous and sedimentary, occurring chiefly as carbonate, sulphate, silicate, phosphate, and fluoride. There are, in fact, whole ranges of mountains composed largely of calcium carbonate. Calcium is also a common mineral ingredient of most natural waters. Finally, animal skeletons owe their rigidity mainly to calcium phosphate, and the shells of molluscs and of birds' eggs to the carbonate.

The metal forms 3.47 per cent, of the older or primitive part of the earth's crust, or 3.25 per cent, of the outer part of the earth, including crust and sea. The amount of calcium in sea-water is from 0.03 per cent, to 0.05 per cent.

Calcium has also been found in meteorites, and by spectral analysis in the sun and fixed stars.

The chief calcium minerals, together with their more important physical constants, are given in the table on the following page.

Calcium History

Compounds of calcium have been employed for building purposes since very early times. A mortar composed of sand and either lime or burnt gypsum was used by the Egyptians, and in the first century a.d. Dioscorides and Pliny described lime-burning and slaking. In 1693 Homberg heated together sal-ammoniac and lime for the production of Homberg's phosphorus, a phosphorescent calcium chloride. In 1722 Hofmann showed that lime was a distinct earth. Black noted its alkalinity in 1755. Lime was regarded as a simple body until the time of Lavoisier, who suspected it to be an oxide. The metal was isolated by Davy in 1808, and independently by Berzelius and Pontin.

Neighbours

Chemical Elements
¹¹Na 23.0 Sodium	¹²Mg 24.3 Magnesium	¹³Al 27.0 Aluminium
¹⁹K 39.1 Potassium	²⁰Ca 40.1 Calcium	²¹Sc 45.0 Scandium
³⁷Rb 85.5 Rubidium	³⁸Sr 87.6 Strontium	³⁹Y 88.9 Yttrium