Chemical elements
    Physical Properties
    Chemical Properties
    PDB 158d-1ajq
    PDB 1ak9-1ayk
    PDB 1ayo-1bg7
    PDB 1bg9-1byh
    PDB 1byn-1c8q
    PDB 1c8t-1cq1
    PDB 1cq9-1daq
    PDB 1dav-1dva
    PDB 1dvi-1el1
    PDB 1ela-1f4n
    PDB 1f4o-1fkq
    PDB 1fkv-1fzd
    PDB 1fze-1g9i
    PDB 1g9j-1gr3
    PDB 1gsl-1h5h
    PDB 1h5i-1hn4
    PDB 1hny-1i9z
    PDB 1ia6-1iyi
    PDB 1iz7-1jc2
    PDB 1jc9-1jui
    PDB 1jv2-1kck
    PDB 1kcl-1kvx
    PDB 1kvy-1led
    PDB 1lem-1lqd
    PDB 1lqe-1may
    PDB 1mbq-1mxe
    PDB 1mxg-1nfy
    PDB 1ng0-1nwg
    PDB 1nwk-1o3g
    PDB 1o3h-1om7
    PDB 1om8-1p7v
    PDB 1p7w-1pva
    PDB 1pvb-1qdo
    PDB 1qdt-1qq9
    PDB 1qqj-1rin
    PDB 1rio-1s10
    PDB 1s18-1scv
    PDB 1sdd-1su4
    PDB 1sub-1tf4
    PDB 1tf8-1top
    PDB 1tpa-1ujb
    PDB 1ujc-1uyy
    PDB 1uyz-1v73
    PDB 1v7v-1w2k
    PDB 1w2m-1wua
    PDB 1wun-1xkv
    PDB 1xmf-1y3x
    PDB 1y3y-1yqr
    PDB 1yr5-1zde
    PDB 1zdp-2a3x
    PDB 2a3y-2arb
    PDB 2are-2bd2
    PDB 2bd3-2bu4
    PDB 2bue-2c6g
    PDB 2c6p-2cy6
    PDB 2cyf-2dso
    PDB 2dtw-2eab
    PDB 2eac-2fe1
    PDB 2ff1-2fwn
    PDB 2fws-2gjp
    PDB 2gjr-2hd9
    PDB 2hes-2i6o
    PDB 2i7a-2ivz
    PDB 2iwa-2j7g
    PDB 2j7h-2jke
    PDB 2jkh-2kuh
    PDB 2kxv-2o1k
    PDB 2o39-2ovz
    PDB 2ow0-2pf2
    PDB 2pfj-2pyz
    PDB 2pz0-2qu1
    PDB 2qua-2re1
    PDB 2rex-2tmv
    PDB 2tn4-2vcb
    PDB 2vcc-2vqy
    PDB 2vr0-2w3i
    PDB 2w3j-2wlj
    PDB 2wm4-2wzs
    PDB 2x0g-2xmr
    PDB 2xn5-2z2z
    PDB 2z30-2zn9
    PDB 2zni-3a51
    PDB 3a5l-3ahw
    PDB 3ai7-3bcf
    PDB 3bdc-3bx1
    PDB 3bxi-3ch2
    PDB 3chj-3d34
    PDB 3d3i-3djl
    PDB 3dng-3e4q
    PDB 3e5s-3eqf
    PDB 3eqg-3faq
    PDB 3faw-3fou
    PDB 3foz-3gci
    PDB 3gcj-3gwz
    PDB 3gxo-3hjr
    PDB 3hkr-3i4i
    PDB 3i4p-3io6
    PDB 3ior-3k5m
    PDB 3k5s-3kqa
    PDB 3kqf-3lei
    PDB 3lek-3lum
    PDB 3lun-3mip
    PDB 3mis-3n7b
    PDB 3n7x-3nvn
    PDB 3nx7-3owf
    PDB 3ox5-3prq
    PDB 3prr-3sg5
    PDB 3sg6-3u39
    PDB 3u43-3vpp
    PDB 3zqx-4awy
    PDB 4awz-4dtu
    PDB 4dtx-4eoa
    PDB 4epz-5apr
    PDB 5bca-8tln
    PDB 966c-9rnt

Element Calcium, Ca, Alkaline Earth Metal

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.


Chemical Elements


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