Sodium
alkali metal · period 3 · group 1 (alkali metals (and hydrogen)) · s-block
Sodium is a chemical element with the symbol Na (from Latin natrium) and atomic number 11. It is a soft, silvery-white, highly reactive metal.
What the numbers say
At standard temperature and pressure Sodium is a solid, sitting in period 3, group 1 of the s-block.
Its melting point of 371 K (98 °C) is the 89th highest of the 110 elements with a measured value — mid-range among the elements.
At 0.968 g/cm³ it is the 83rd densest of 96 elements with a quoted density.
Pauling electronegativity is 0.93. Paired with oxygen (3.44) that is a difference of 2.51, 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.
It is reported in 2 oxidation states (-1, 1), which sets how many distinct compounds and phases it can form.
First identified in 1807.
Crystal structure
Solid Sodium 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.
Where sodium shows up in engineering materials
1 entry in the materials library names it directly:
- PTFE (Teflon) — Fluoropolymer
Crystallographic examples
Sodium or one of its compounds is a textbook example for this crystal system:
- Cubic (isometric) — Cu, Al, Fe-α (BCC), NaCl, diamond, spinel MgAl₂O₄
Check it against computed structures
The structure search queries the Materials Project, OQMD and the Open Materials Database for computed crystal structures containing Na — with DFT formation energy, hull stability and band gap where the provider publishes them.
K 2 · L 8 · M 1
Properties
| Atomic number | 11 |
|---|---|
| Atomic mass | 22.989769282 u |
| Series | alkali metal |
| Group | 1 |
| Period | 3 |
| Block | s-block |
| Phase at STP | Solid |
| Density | 0.968 g/cm³ |
| Melting point | 370.94 K (98 °C) |
| Boiling point | 1156.09 K (883 °C) |
| Electronegativity (Pauling) | 0.93 |
| Electron configuration | [Ne] 3s¹ |
| Crystal structure | Body-centered Cubic |
| Oxidation states | -1,1 |
| Discovered | 1807 |
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See Na in context with all 118 elements.
Working with sodium in a real design?
Ask the materials chat how Na behaves in your alloy system, what it does to weldability, and which grades to look at — with the source of every number named.