Atomic Properties of Ca
- Atomic Number of Ca
- 20
- Atomic Mass of Ca
- 40.0780 u
- Electron Configuration
- [Ar] 4s2
- Electronegativity
- 1.00
- Block
- s-block
- Group
- 2
- Period
- 4
Calcium is famous for bones, but bone is not a block of calcium metal. Its rigid mineral phase is largely a calcium phosphate related to hydroxyapatite, woven through a collagen framework. Teeth use similar mineral chemistry. Bone remains living tissue that is continually remodeled, and vitamin D helps the body absorb calcium from food.
Calcium ions do more than build. Cells keep Ca2+ concentrations under tight control, then release brief pulses as signals. Those changes help trigger muscle contraction, neurotransmitter release, blood clotting, and many enzyme responses. The skeleton also serves as a calcium reservoir, linking structural and signaling roles. Too little or too much calcium in blood can disrupt physiology, so “essential” describes balance, not unlimited intake.
Earth stores calcium in limestone, chalk, marble, gypsum, and countless silicate minerals. Heating limestone drives off carbon dioxide and produces lime, calcium oxide. Add water to make calcium hydroxide, then combine lime chemistry with silica-rich materials to build cement and concrete. Calcium compounds support structures from shells and skeletons to roads and towers.
Pure calcium is a reactive silvery group 2 metal with few everyday uses. Its compounds are the familiar Builders. Calcium salts also give an orange-red flame, a spectral signal rather than proof that every calcium material burns.
Most natural calcium is calcium-40, while calcium-48 undergoes double-beta decay so slowly that it persists in nature. Calcium's story crosses scales cleanly: ions flash messages inside cells, phosphate mineral carries bodies, and carbonate rock becomes the binder in a city skyline.