20Solid
Ca 40.078 Atomic mass · uAlkaline earth metals
Calcium
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.
Discovery Ancient (Humphry Davy)
K2L8M8N2
Physical properties
Values for the element in its standard state.
- Density
- 1.55g/cm³
- Melting point
- 1,115K
- Boiling point
- 1,757K
- Atomic radius
- 174pm
- Bonding type
- Metallic
- Molar heat
- 25.929J/(mol·K)
Inside the atom
Electron arrangement and the energy behind its behavior.
Full electron configuration
1s, 2 electrons; 2s, 2 electrons; 2p, 6 electrons; 3s, 2 electrons; 3p, 6 electrons; 4s, 2 electrons;
[Ar] represents 18 core electrons. The full view shows them explicitly.
20 electrons Orbital order preserved from source
- Electronegativity
- 1Pauling scale
- First ionization energy
- 590kJ/mol
- Electron affinity
- 2kJ/mol
- Van der Waals radius
- Not available
Ca CalciumAtomic number 20
590kJ/mol
Atomic numberGaps indicate unavailable data
About calcium
- Appearance
- Not recorded
- Discovery
- Ancient (Humphry Davy)
- Data source
- Read the reference
A missing value means it is unavailable in this reference dataset. Values can vary with measurement method and conditions.