Calcium

Document v1 · published by Koskamo · updated 2026-10-04

Calcium (Ca) is chemical element 20, an alkaline earth metal in group 2, period 4 (PubChem).

Atomic number: 20
Symbol: Ca
Group: 2
Period: 4
Atomic mass: 40.08 u
Electron configuration: [Ar]4s2
Electronegativity (Pauling scale): 1
Atomic radius (van der Waals): 231 pm
Ionization energy: 6.113 eV
Oxidation states: +2
Standard state: Solid
Melting point: 1115 K
Boiling point: 1757 K
Density: 1.54 g/cm³
Chemical group: Alkaline earth metal
Year discovered: Ancient

Source and provenance

Original source: pubchem.ncbi.nlm.nih.gov
Published on Koskamo by: Koskamo
Citation version: Document v1
Reuse: PubChem periodic table data (NIH/NLM, pubchem.ncbi.nlm.nih.gov/ptable); group and period from Jefferson Lab via PubChem

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Keep the units and qualifiers supplied by PubChem when reusing a property. An omitted property is not a zero value. Follow the element’s source link for its full context.

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Version history

Published by Koskamo2026-10-04
Version 1