56BaBarium137.3277[Xe] 6s²
alkaline earth metal
Barium
Barium is a chemical element with symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Because of its high chemical reactivity barium is never found in nature as a free element.
A stylized shell model. Electrons are quantum objects, not particles following these literal paths. Sizes and motion are illustrative.
Electrons by shell
Electron configuration
6s2
54 is the [Xe] core total across five shells.
At a glance
- Atomic number
- 56
- Atomic mass
- 137.3277 u
- Phase
- Solid
- Density
- 3.51 g/cm³
- Melting point
- 1,000 K
- Boiling point
- 2,118 K
- First ionization energy
- 502.9 kJ/mol
- Electronegativity
- 0.89
- Electron affinity
- 13.954 kJ/mol
- Molar heat capacity
- 28.07 J/(mol·K)
- Period
- 6
- Appearance
- Unavailable
Conditions and isotopes affect measured properties. Some properties of short-lived elements are predicted. Electronegativity uses the Pauling scale.
Keep exploring
Explore the stories, imagery, and reference data in more depth. Properties with no value in the reference are marked unavailable.