Barium
alkaline earth metal · period 6 · group 2 (alkaline earth metals) · s-block
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal.
What the numbers say
At standard temperature and pressure Barium is a solid, sitting in period 6, group 2 of the s-block.
Its melting point of 1000 K (727 °C) is the 65th highest of the 110 elements with a measured value — mid-range among the elements.
At 3.51 g/cm³ it is the 68th densest of 96 elements with a quoted density.
Pauling electronegativity is 0.89. Paired with oxygen (3.44) that is a difference of 2.55, which puts the bond predominantly ionic — expect a stable oxide ceramic.
In the solid state it takes a body-centered cubic structure — BCC packing is stronger but shows a ductile-to-brittle transition as temperature drops.
First identified in 1808.
Crystal structure
Solid Barium adopts a Body-centered Cubic arrangement, in the Cubic (isometric) system — axes a = b = c, angles α = β = γ = 90°. Symmetry controls the anisotropy of stiffness and thermal expansion, and the available slip systems set how far the metal deforms before it fractures.
Check it against computed structures
The structure search queries the Materials Project, OQMD and the Open Materials Database for computed crystal structures containing Ba — with DFT formation energy, hull stability and band gap where the provider publishes them.
K 2 · L 8 · M 18 · N 18 · O 8 · P 2
Properties
| Atomic number | 56 |
|---|---|
| Atomic mass | 137.3277 u |
| Series | alkaline earth metal |
| Group | 2 |
| Period | 6 |
| Block | s-block |
| Phase at STP | Solid |
| Density | 3.51 g/cm³ |
| Melting point | 1000 K (727 °C) |
| Boiling point | 2118 K (1845 °C) |
| Electronegativity (Pauling) | 0.89 |
| Electron configuration | [Xe] 6s² |
| Crystal structure | Body-centered Cubic |
| Oxidation states | 2 |
| Discovered | 1808 |
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See Ba in context with all 118 elements.
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Ask the materials chat how Ba behaves in your alloy system, what it does to weldability, and which grades to look at — with the source of every number named.