Uranium
actinide · period 7 · group 3 · f-block
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table.
What the numbers say
At standard temperature and pressure Uranium is a solid, sitting in period 7, group 3 of the f-block.
Its melting point of 1405 K (1132 °C) is the 43rd highest of the 110 elements with a measured value — mid-range among the elements.
At 19.05 g/cm³ it is the 9th densest of 96 elements with a quoted density.
Pauling electronegativity is 1.38. Paired with oxygen (3.44) that is a difference of 2.06, which puts the bond predominantly ionic — expect a stable oxide ceramic.
In the solid state it takes a base orthorhombic structure.
It is reported in 5 oxidation states (2, 3, 4, 5, 6), which sets how many distinct compounds and phases it can form.
First identified in 1789.
Crystal structure
Solid Uranium adopts a Base Orthorhombic arrangement, in the Orthorhombic 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 U — with DFT formation energy, hull stability and band gap where the provider publishes them.
K 2 · L 8 · M 18 · N 32 · O 21 · P 9 · Q 2
Properties
| Atomic number | 92 |
|---|---|
| Atomic mass | 238.028913 u |
| Series | actinide |
| Group | 3 |
| Period | 7 |
| Block | f-block |
| Phase at STP | Solid |
| Density | 19.05 g/cm³ |
| Melting point | 1405.3 K (1132 °C) |
| Boiling point | 4404 K (4131 °C) |
| Electronegativity (Pauling) | 1.38 |
| Electron configuration | [Rn] 5f³ 6d¹ 7s² |
| Crystal structure | Base Orthorhombic |
| Oxidation states | 2,3,4,5,6 |
| Discovered | 1789 |
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See U in context with all 118 elements.
Working with uranium in a real design?
Ask the materials chat how U behaves in your alloy system, what it does to weldability, and which grades to look at — with the source of every number named.