Calcium
Alkaline Earth Metal
Calcium (Ca) is a chemical element with atomic number 20, classified as a alkaline earth metal. At room temperature it is a solid. It was discovered in 1808 by Humphry Davy.
Properties
- Atomic number
- 20
- Atomic mass
- 40.078 u
- Category
- Alkaline Earth Metal
- Group
- 2
- Period
- 4
- Block
- s-block
- Electron configuration
- [Ar] 4s²
- Phase at STP
- Solid
- Density
- 1.54 g/cm³
- Melting point
- 1115 K (841.9 °C)
- Boiling point
- 1757 K (1483.8 °C)
- Electronegativity
- 1
- Atomic radius
- 194 pm
- Ionization energy
- 6.113 eV
- Discovery
- 1808 · Humphry Davy
Common uses
Bones and teeth, concrete, steel production, antacids
Did you know?
Essential for strong bones and teeth - deficiency causes rickets.
Compounds you can make with calcium
Calcium appears in 6 compounds in our periodic table sandbox. Each one is a real substance with its true chemical formula — combine the right elements in the right ratio below to discover it.
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CaCO3
Calcium Carbonate
The mineral in limestone, chalk, marble, eggshells, and seashells.
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CaO
Calcium Oxide (Quicklime)
Quicklime, used in cement, steelmaking, and historically in stage "limelight".
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CaCl2
Calcium Chloride
A salt used for de-icing roads and as a drying agent.
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CaF2
Calcium Fluoride (Fluorite)
The mineral fluorite, a source of fluorine and used in optics.
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Ca(OH)2
Calcium Hydroxide (Slaked Lime)
Slaked lime, used in mortar, plaster, and to treat acidic soil and water.
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CaSO4
Calcium Sulfate (Gypsum)
Gypsum, the mineral in drywall, plaster of Paris, and blackboard chalk.