Calcium is the most abundant metal in the human body. It is also the fifth most common element on Earth. It occurs in many minerals, such as calcite and aragonite, which are formed from calcium carbonate. Bones in animal skeletons contain calcium phosphate. Also, the hard outer layers of many other animals, such as the shells of sea snails, are made of calcium carbonate.

This element is very important in our diet, we obtain it mainly in dairy products. Antacid tablets, used to treat indigestion, contain calcium carbonate. This compound reacts with acid in the stomach. Calcium compounds are also common in building materials. Plasterboard, which is used to smooth walls, writing chalk, and gypsum are made from the mineral gypsum. Calcium oxide is an important ingredient in cement and aids in the setting process.

Summary of properties (Ca)

Atomic weight40.078(4)
Discoverer (year)Davy, Humphry (1808)
Natural formmetallic solid (face centered cubic)
Electron configuration[Ar] 4s2
Melting point (ºC)839
Boiling point (ºC)1484
Abundance in earth's crust (ppm)41500
Isotope (abundance)40Ca (96.941), 42Ca (0.647), 43Ca (0.135), 44Ca (2.086), 46Ca (0.004), 48Ca (0.187)
Density g/cm31.55
Van der Waals radius (pm)231
Covalent radius (pm)174
Electronegativity (Pauling)1.36
Vaporization enthalpy (kJ/mol)150.00
Enthalpy of fusion (kJ/mol)8.54
Specific heat capacity (J/g·K) at 25ºC and 1 atm0.65
Thermal conductivity (W/cm·K) at 25ºC and 1 atm2.010
Oxidation state+2
Electron affinity (eV)0.02
1st Ionization potential (eV)6.1132

Back to the Periodic Table of the Elements.