Calcium is the 5th element in the Periodic Table and third most abundant metal in the earth's crust that accounts to 3.5%. It is classified among the alkaline earth metals. Calcium was first used by the Romans in the 1st century A.D. but it wasn't until 1808 that English scientist Sir Humphrey Davy discovered this element. It comes from the Latin word calcis meaning "lime". Natural calcium can be sourced from gypsum, lime, and chalk.
Calcium is a trimorphic type of metal, which is harder than sodium but softer compared with aluminum. Unlike other alkaline metals, calcium is less chemically reactive and doesn't burn skin. Calcium combines with other elements to form certain compounds that are abundant in the earth's crust. Some of the natural forms of calcium are: limestone (CaCo3), fluorite (CaF2) and gypsum (CaSO4·2H2O). Apatite contains calcium in the fluorophosphates or chlorophosphate phase.
When calcium comes in contact with air, it forms a coating of nitride and oxide to minimize further corrosion. When subjected to very high temperature in the air, calcium can burn to produce nitride.
Chemical properties of calcium – atomic configurations
Calcium's symbol is "Ca" and has an atomic number 20, with atomic weight 40.078amu. The chemical properties of calcium include its melting point, which is 839.0 +/- 2°C while its boiling point is 1484.0ºC with a valence of 2. This means that calcium needs more than 14 times of needed heat to boil water. This is only achievable with the use of special industry or laboratory equipment.
The specific gravity of calcium is 1.55 equal to 20ºC. A single atom of calcium contains 20 protons/electrons and 20 neutrons. Chemical properties of calcium, furthermore, include a cubic crystal structure, a white silvery color, and a density of 1.55 g/cm3 at 293 K. Calcium has four energy levels, with electrons count of 2, 8, 8, and 2 respectively.
Chemical properties of calcium – the isotopes and corresponding half-life
Ca-40 has a stable half life, Ca41 has a half life of 103,000 years, Ca-42 up to 44, 46 and 48 all have stable half lives, Ca-45 isotope's half life is 162.7 days, Ca47 has 4.5 days, and the shortest-lived isotope is Ca-49 with a half life of 8.7 minutes.
Calcium easily combines with other element to form another compound making it a vital agent in many industries. In living species, calcium is necessary to maintain bone density among animals including humans.