Calcium (Ca)

Calcium is a chemical element with symbol Ca and atomic number 20. Calcium is a soft gray Group 2 alkaline earth metal, fifth-most-abundant element by mass in the Earth's crust.

Atomic Number

20

Atomic Mass

40.078 u

Category

alkaline earth

Phase

solid

Density

1.55 g/cm³

Electron Shells

2, 8, 8, 2

Atomic Structure

Protons: 20 • Electrons: 20 • Neutrons: Varies by isotope

Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

Discovery

1808 • Humphry Davy