Atomic number:20

Group numbers:2

Period:4

Electronic configuration:[Ar] 4s²

Formal oxidation number:+2

Electronegativities:1

Atomic radius / pm:197.4

Relative atomic mass:40.078 ± 0.004

 

Calcium was discovered by Sir Humphry Davy (GB) in 1808. The origin of the name comes from the Latin word calx meaning lime. It is a fairly hard, silvery-white metal. Exposed surfaces form oxides and nitrides. Calcium reacts with water and oxygen. It only occurs in compounds. Calcium is obtained from minerals like chalk, limestone and marble. Pure metal is produced by replacing the calcium in lime (CaCO3) with aluminium in hot, low pressure retorts. Calcium is used by many forms of life to make shells and bones, as a pure metal it has little use, however two of its compounds, lime (CaO) and gypsum (CaSO4), are in great demand by a number of industries.

Density / g dm^-3:1550 (293 K)

 1365 (m.p.)

Molar volume / cm³mol^-1:25.86 (293 K)

 29.36 (m.p.)

Electrical resistivity / μΩcm:3.91 (20 °C)

Thermal conductivity / W m^-1K^-1:190

Melting point / °C:842

Boiling point / °C:1484

Heat of fusion / kJ mol^-1:9.33

Heat of vaporization / kJ mol^-1:150.6

Heat of atomization / kJ mol^-1:177.74

1st ionization energy / kJ mol^-1:589.83

2nd ionization energy / kJ mol^-1:1145.46

3rd ionization energy / kJ mol^-1:4912.40

in the atmosphere / ppm:-

in the Earth's crust / ppm:52900

in the oceans / ppm:400