Ca
40.078Calcium
Kalsiyum
Calcium is an alkaline earth metal with atomic number 20. It is essential for bones, teeth, muscles and nerve signaling, and calcium compounds such as limestone, quicklime, gypsum and calcium chloride are important in construction, agriculture and industry.
20
40.078 g/mol
[Ar] 4s²
2 | 8 | 8 | 2
1
1.54 g/cm³
841.9 °C
1483.8 °C
Humphry Davy
Calcium was isolated by Humphry Davy in 1808 by electrolysis. Its name comes from the Latin calx, meaning lime, because calcium compounds occur in limestone and lime.
Calcium-40
Natural abundance: About 96.9%. The most abundant stable isotope of calcium.Calcium-42
Natural abundance: About 0.65%. Stable isotope of calcium.Calcium-44
Natural abundance: About 2.1%. Stable isotope used in isotope studies.Calcium-48
Natural abundance: About 0.19%. Half-life: About 4.4 x 10¹⁹ years. Very long-lived double-beta-decay isotope used in nuclear science.CaCO₃
Calcium CarbonateMain component of limestone, marble, chalk and many shells.CaO
Calcium OxideQuicklime used in cement, steelmaking and water treatment.Ca(OH)₂
Calcium HydroxideSlaked lime used in construction, water treatment and soil chemistry.CaSO₄
Calcium SulfateFound in gypsum and used in plaster and wallboard.CaF₂
Calcium FluorideFluorite mineral used in metallurgy, optics and hydrofluoric acid production.Ca₃(PO₄)₂
Calcium PhosphateMineral component of bones and teeth and raw material for phosphate fertilizers.- Limestone and cement production for construction
- Quicklime and slaked lime for cement, steelmaking, soil treatment and water treatment
- Calcium carbide for acetylene production
- Gypsum for plaster, wallboard and casts
- Calcium metal as a reducing agent and alloying additive
- Calcium chloride for de-icing, drying and dust control
Calcium is essential for living organisms. In humans it is the main mineral in bones and teeth, and Ca²⁺ ions are important in muscle contraction, blood clotting, nerve signaling and cell regulation.
- Calcium is the most abundant metal in the human body.
- Bones and teeth store most of the body’s calcium as calcium phosphate minerals.
- The calcium carbonate equilibrium with carbon dioxide and water explains limestone caves, stalactites and stalagmites.
- Calcium gives a brick-red to orange-red color in flame tests.
- Calcium compounds are major ingredients in limestone caves, cement and plaster.
- Calcium has atomic number 20 and belongs to group 2, the alkaline earth metals.
- Its electron configuration is [Ar] 4s².
- Calcium commonly forms Ca²⁺ by losing two valence electrons.
- Water hardness is mainly caused by dissolved Ca²⁺ and Mg²⁺ ions.
What is the atomic number of calcium?
The atomic number of calcium is 20.
What is the electron configuration of calcium?
Calcium has the electron configuration [Ar] 4s².
Why is calcium important for the body?
Calcium is needed for bones, teeth, muscle contraction, blood clotting, nerve signaling and cell regulation.
What causes water hardness?
Water hardness is mainly caused by dissolved calcium and magnesium ions.
What color is calcium in a flame test?
Calcium gives a brick-red to orange-red color in flame tests.
What is calcium used for?
Calcium and its compounds are used in cement, limestone, plaster, water treatment, soil treatment, de-icing, alloys and reducing agents.