Calcium

Alkaline earth metal · atomic number 20

2040.0784CaCalciumSolidAlkaline earth metal

Calcium is a chemical element with symbol Ca and atomic number 20. Calcium is a soft gray alkaline earth metal, fifth-most-abundant element by mass in the Earth's crust. The ion Ca2+ is also the fifth-most-abundant dissolved ion in seawater by both molarity and mass, after sodium, chloride, magnesium, and sulfate.

Properties of Calcium

Element category	Alkaline earth metal
Atomic number	20
Atomic mass	40.0784 u
Phase at STP	Solid
Group	2
Period	4
Block	s
Electron configuration	[Ar] 4s2
Electrons per shell	2, 8, 8, 2
Electronegativity (Pauling)	1
Melting point	1115 K (842 °C)
Boiling point	1757 K (1484 °C)
Density	1.55 g/cm3
Discovered by	Humphry Davy

← Potassium · Periodic table · Scandium → Sc

About the alkaline earth metal group

Reactive group-2 metals a step calmer than the alkalis: magnesium, calcium and the structural and biological workhorses among them.

Data: Periodic-Table-JSON (CC BY-SA 3.0) · stored statically on our server. https://en.wikipedia.org/wiki/Calcium

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🧪 Reactive nonmetal

11 elements: Elements that readily gain or share electrons — the building blocks of water, air, living tissue and most organic chemistry.

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6 elements: Full outer electron shells make these gases almost inert: they barely react, glow in discharge lamps and are used to create unreactive atmospheres.

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6 elements: Soft, wildly reactive metals of group 1 — they fizz in water and never occur pure in nature. Lithium, sodium, potassium and friends.

🧪 Alkaline earth metal

6 elements: Reactive group-2 metals a step calmer than the alkalis: magnesium, calcium and the structural and biological workhorses among them.

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