کلسیم

Calcium is a chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 and a standard oxidation state of 2. The element was discovered in 1808. Its electron configuration is [Ar] 4s² or 1s² 2s² 2p⁶ 3s² 3p⁶ 4s². The ionic radius is 134, and its electronegativity is 1.00.

Physically, calcium has a melting point of 838.85 and a boiling point of 1483.85. It exhibits an electrical conductivity of 28200000 and a standard molar entropy of 41.6. The canonical SMILES representation is [Ca]. In Unicode, the character is "鈣".

In scientific literature, the term "calcium" appears in 713,024 PubMed records. It is referenced by 4,896 other encyclopedia articles. PubChem lists its weight as 40.08 and its charge as 0. It has zero hydrogen bond donors and acceptors, with a topological polar surface area of 0.