Calcium is a metallic element, fifth in abundance in the earth's crust, of which it forms more than 3%. It is an essential constituent of leaves, bones, teeth, and shells.
The metal is a silvery colour and is rather hard. 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.
Calcium does not occur free in nature. Calcium is found mostly as limestone, gypsum and fluorite. Stalagmites and stalactites contain calcium carbonate.
Discoveror: Sir Humphrey Davy
Date discovered: 1808
Discovered at: England
Meaning of name: From the Latin word "calx" meaning "lime"
Standard state: solid at 298 K
Colour: silvery white
Density of solid at ambient temperature/kg m-3: 1550
Molar volume/cm3: 26.20
Covalent (single bond):
Pauling radius for the ion [Ca]-: no data
Valence shell orbital radius maxima (Rmax)
|radius||183.9||no data||no data||no data|
Both values are quoted on the Pauling scale.
Allred Rochow: 1.04
structure: ccp (cubic close-packed)
The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.
melting point: 1115
boiling point: 1757
Enthalpies /kJ mol-1
single bond enthalpies:
Ionization enthalpies /kJ mol-1
This section gives some data for naturally occurring isotopes.
||% natural abundance
|40Ca||39.9625906 (13)||96.941 (13)|
|42Ca||41.9586176 (13)||0.647 (3)|
|43Ca||42.9587662 (13)||0.135 (3)|
|44Ca||43.9554806 (14)||2.086 (5)|
|46Ca||45.953689 (4)||0.004 (3)|
|48Ca||47.952533 (4)||0.187 (3)|