CALCIUM
ALKALINE EARTH METAL
| 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(4) |
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. The price of 99.8 % pure calcium granules is 126.90 € for 1000 g.
| 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 |
| First ionization energy / kJ mol-1: | 589.83 |
| Second ionization energy / kJ mol-1: | 1145.46 |
| Third ionization energy / kJ mol-1: | 4912.40 |
| in the atmosphere / ppm: | - |
| in the Earth's crust / ppm: | 52900 |
| in the oceans / ppm: | 400 |
| Crystal structure: | face-centered cubic |
| Unit-cell dimensions / pm: | a=558.84 |
| Space group: | Fm3m |
| Isotope | Relative atomic mass | Mass percent (%) |
|---|---|---|
| 40Ca | 39.9625911(3) | 96.941(18) |
| 42Ca | 41.9586183(4) | 0.647(9) |
| 43Ca | 42.9587668(5) | 0.135(6) |
| 44Ca | 43.9554811(9) | 2.086(12) |
| 46Ca | 45.953693(3) | 0.004(3) |
| 48Ca | 47.952534(4) | 0.187(4) |
| Balanced half-reaction | Eo / V | |
|---|---|---|
| Ca2+ + 2e- → Ca(s) | - 2.866 | |
| CaO + 2H+ + 2e- → Ca(s) + H2O | - 1.90 | |
| Ca(OH)2(s) + 2e- → Ca(s) + 2OH- | - 3.03 |
| 19 Potassium | ← | 20 Calcium | → | 21 Scandium |
Citing this page:
Generalic, Eni. "Calcium." EniG. Periodic Table of the Elements. KTF-Split, 18 Jan. 2024. Web. {Date of access}. <https://www.periodni.com/ca.html>.
