Element 56
Barium (Ba)
Barium (Ba) is element 56 of the periodic table, a alkaline earth metal in period 6, group 2 (s-block) with an atomic mass of 137.33 and is a solid at standard conditions.
At a glance
- Atomic number
- 56
- Symbol
- Ba
- Atomic mass
- 137.33 u
- Category
- Alkaline earth metals
- Period
- 6
- Group
- 2
- Block
- s-block
- Phase at STP
- solid
Electron structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 6s2
- Shorthand configuration
- [Xe] 6s2
- Electrons per shell
- 2, 8, 18, 18, 8, 2
- Oxidation states
- +1, +2
Physical properties
- Melting point
- 1000 K
- Boiling point
- 2170 K
- Density
- 3.594 g/cm3
- Phase
- solid
Atomic properties
- Electronegativity (Pauling)
- 0.89
- Atomic radius
- 253 pm
- Covalent radius
- 215 pm
- Van der Waals radius
- 268 pm
- First ionization energy
- 503 kJ/mol
- Electron affinity
- 14 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| Ba-138 | 137.90525 | 71.7% | Stable |
Common uses
- X-ray imaging
- Fireworks
- Glass making
- Oil drilling
Discovery
- Year
- 1808
- Discovered by
- Humphry Davy
- Country
- England