Calcium (Ca)
Calcium (Ca) is element 20 of the periodic table, an alkaline earth metal in period 4 and group 2. Its standard atomic weight is 40.078, so one mole of calcium atoms has a mass of 40.078 g. At room temperature it is a solid; it melts at 841.85 °C and boils at 1483.85 °C.
| Atomic number | 20 |
|---|---|
| Symbol | Ca |
| Standard atomic weight | 40.078 |
| Molar mass | 40.078 g/mol |
| Category | Alkaline earth metal |
| Group | 2 |
| Period | 4 |
| Block | s-block |
| Electron configuration | [Ar] 4s2 |
| Oxidation states | +2 |
| Electronegativity (Pauling) | 1 |
| Atomic radius (van der Waals) | 231 pm |
| First ionisation energy | 6.113 eV (589.8 kJ/mol) |
| Electron affinity | — |
| State at room temperature | Solid |
| Melting point | 1115 K (841.85 °C) |
| Boiling point | 1757 K (1483.85 °C) |
| Density | 1.54 g/cm³ |
| Discovered | Known since antiquity |
Group 2
Calculate with Calcium
Atomic weight: IUPAC CIAAW standard atomic weight. Other properties: PubChem (U.S. National Library of Medicine, public domain). Values such as melting point and radius depend on how they were measured; check a data book for precise work.