Discovery date : 1808
Discovered by: Humphry Davy
Origin of the name:The name is derived from the Latin 'calx' meaning lime.
Allotropes :
~>CALCIUM is a chemical element with symbol Ca and atomic number 20. An alkaline earth metal, calcium is a reactive pale yellow metal that forms a dark oxide-nitride layer when exposed to air.
| FACT BOX | |||
| Group | 2 | Melting point | 842°C, 1548°F, 1115 K |
| Period | 4 | Boiling point | 1484°C, 2703°F, 1757 K |
| Block | s | Density (g cm−3) | 1.54 |
| Atomic number | 20 | Relative atomic mass | 40.078 |
| State at 20°C | Solid | Key isotopes | 40 Ca |
| Electron configuration | [Ar] 4s2 | CAS number | 7440-70-2 |
| ChemSpider ID | 4573905 | ChemSpider is a free chemical structure database | |
Lime (calcium oxide, CaO) was the useful material obtained by heating limestone and used for centuries to make plaster and mortar. Antoine Lavoisier classified it as an ‘earth’ because it seemed impossible to reduce it further, but he suspected it was the oxide of an unknown element. In 1808, Humphry Davy tried to reduce moist lime by electrolysis, just as he had done with sodium and potassium, but he was not successful. So he tried a mixture of lime and mercury oxide and while this produced an amalgam of calcium and mercury, it was not enough to confirm that he’d obtained a new element. (Jöns Jacob Berzelius had conducted a similar experiment and also obtained the amalgam.) Davy tried using more lime in the mixture and produced more of the amalgam from which he distilled off the mercury leaving just calcium.