Barium

Atomic number

56

Atomic mass (u)

137.33

Category

Alkaline earth metal

Standard state

Solid

Melting point

726.85 °C (1000 K)

Boiling point

1896.85 °C (2170 K)

Density (g/cm³)

3.62

Electronegativity (Pauling)

0.89

Electron configuration

[Xe]6s2

Oxidation states

+2

Atomic radius (pm)

268

First ionization energy (eV)

5.212

Discovery & recognition

Discovery year / period (PubChem)

1808

Discovery credited to (RSC)

Humphry Davy

Date or period recorded by RSC

1808

Discovery place

Royal Institution, London, United Kingdom (metal isolation)

An ancient date does not identify a first human discovery. Different references may date observation, isolation and formal recognition differently.

Natural occurrence & production

The creation of an element’s nuclei and its concentration into terrestrial deposits are different processes. The occurrence note below concerns its presence or production on Earth; it is not a complete account of nucleosynthesis.

“Barium occurs only in combination with other elements.”

Royal Society of Chemistry · occurrence excerpt ↗

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Reference values are not product specifications. Blank values have not been estimated. For superheavy elements, some properties and family assignments are theoretical or incompletely measured.