Barium (Ba)

Barium (Ba) is element 56, an alkaline earth metal. Atomic mass 137.327, configuration [Xe] 6s². Properties, isotopes, oxidation states, uses and history, with an interactive 3D atom model.

Open Barium in the interactive periodic table

Key facts

Atomic number56
SymbolBa
Standard atomic weight137.327(7)
CategoryAlkaline Earth Metal
Group2
Period6
State at room temperatureSolid
Electron configuration[Xe] 6s²
Valence electrons2
Common oxidation states+2
Common ionsBa²⁺
Electronegativity (Pauling)0.89
First ionization energy503 kJ/mol
Electron affinity13.95 kJ/mol
Atomic radius215 pm
Density3.62 g/cm³
Melting point727°C
Boiling point1897°C
Specific heat0.204 J/(g·°C)

Natural isotopes

Common uses

Where it matters

Hazards

History

Discovered1808
Discovered byHumphry Davy
NameFrom Greek barys (heavy)