Calcium

Name:Calcium
Symbol:Ca
Atomic Number:20
Atomic Mass:40.078
Density: 26.20 g/cm^3
Melting Point:842 °C
Boiling Point:1484 °C
Group Number:2
Group Name:Alkaline Earth Metals
Standard State:Solid at room temperature
Color:silvery white
Classification:Metallic
Calcium is a metallic element, fifth in abundance in the earth's crust, of which it forms more than 3%. It is an essential constituent of leaves, bones, teeth, and shells. The metal is a silvery color and is rather hard. Chemically it is one of the alkaline earth elements; it readily forms a white coating of nitride in air, reacts with water, burns with a yellow-red flame, forming largely the nitride.
Calcium does not occur free in nature. Calcium is found mostly as limestone, gypsum and fluorite. Stalagmites and stalactites contain calcium carbonate.

Isolation

Calcium metal is readily available commercially and there is no need to make it in the laboratory. Commercially it can be made by the electrolysis of molten calcium chloride, CaCl₂.

cathode: Ca²⁺(l) + 2e^- → Ca anode: Cl^-(l) → ¹/₂Cl₂ (g) + e^-

The calcium chloride is made by the action of hydrochloric acid upon calcium carbonate. Calcium chloride is also a byproduct in the Solway process used to make sodium carbonate.

CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

Alternatively, and on small scale, calcium can be made through the reduction of CaO with aluminum or of CaCl₂ with sodium metal

6CaO + 2Al→ 3Ca + Ca₃Al₂O₆

CaCl₂ + 2Na→ Ca + 2NaCl