Uranium (U)

Silvery-gray metal

Uranium is the fuel of nuclear power plants and the most efficient nuclear weapon material, and with [Rn] 5f³ 6d¹ 7s², uranium-235 (0.72% natural abundance) is fissile while U-238 (99.27%) is fertile. Enriching from 0.72% to 3-5% produces reactor fuel; enriching to 90%+ produces weapons material.

Key metrics

Density19.1g/cm³

Melting point1,405K

Boiling point4,404K

Electronegativity1.38Pauling

Discovery

1789discovered

Discovered by: Martin Heinrich Klaproth
Reactivity profile: Radioactive and reactive
Reactivity: Medium
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Rn]}\; \textcolor{#a855f7}{5_{f}^{3}}\; \textcolor{#22c55e}{6_{d}^{1}}\; \textcolor{#ef4444}{7_{s}^{2}}

[Rn] 5f3 6d1 7s2

Wave function

\Psi_{\text{U}} \approx \frac{1}{\sqrt{92!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{92}(\mathbf{r}_{92}) \right|

Probability density $|\Psi|^2$ across the U valence shell.

Crystal structure

Face-Centered Cubic

Lattice constantsa = 1.00

Cell anglesα = β = γ = 90°

Coordination number12

Atoms per cell4

Atomic packing factor0.74

Physical properties

Atomic radius: 156 pm
Ionization energy: 598 kJ/mol
Electron affinity: 50 kJ/mol
Crystal structure: Face-centered cubic

Oxidation states

+3+4+5+6

Acid/base

Basic

Strongly acidicStrongly basic

State at 25 °CSolid

1405 K4404 K298 K

Emission spectrum

4 transitions

380450500550600650700780

VioletBlueGreenYellowRed

436.2nmU I (blue)Violet80%

502.7nmU I (green)Cyan100%

548.5nmU I (green)Green60%

567.1nmU I (yellow)Yellow50%

Dominant line 502.7 nmRange 436–567 nmTransitions 4