Barium (Ba)

Barium is a chemical element with symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal.

Atomic Number

56

Atomic Mass

137.33 u

Category

alkaline earth

Phase

solid

Density

3.51 g/cm³

Electron Shells

2, 8, 18, 18, 8, 2

Atomic Structure

Protons: 56 • Electrons: 56 • Neutrons: Varies by isotope

Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s²

Discovery

1808 • Humphry Davy