Ca
Calcium
Atomic number: 20Mass: 40.078 uCategory: Alkaline Earth Metal
About Calcium
Calcium is the fifth most abundant element in the Earth's crust. It is an essential component of bones, teeth, and shells. It is a reactive metal that, when freshly cut, appears silver-white but quickly oxidises in air.
Properties
Period
4
Group
2
Block
S
Category
Alkaline Earth Metal
Electronegativity
1.00 (Pauling)
Ionization Energy
589.8 kJ/mol
Melting Point
1115 K (842°C)
Boiling Point
1757 K (1484°C)
Density
1.55 g/cm³
Oxidation States
+2
Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
[Ar] 4s²
Shell 1:2e⁻
Shell 2:8e⁻
Shell 3:8e⁻
Shell 4:2e⁻
Real-World Uses
Cement and concrete
Bone and teeth formation
Cheese making
Water treatment
Steelmaking
Fun Fact
Your body contains about 1 kg of calcium — almost all of it stored in your bones and teeth!