Uranium (U)

Actinides · Period 7 · Solid

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Element identity

Atomic number (Z): 92
Symbol: U
Atomic weight / isotope mass number: 238.028 91(3)
Category: Actinides
Physical state (reference): Solid
Period: 7
Group (reference): 3
Block: f

Physical properties

Appearance: Silvery gray metallic, corrodes to a spalling black oxide coat in air
Density: 19.1 g·cm⁻³
Melting point: 1405.3 K / 1132.2 °C / 2070 °F
Boiling point: 4404 K / 4131 °C / 7468 °F
Sublimation point: Not available

Atomic and material properties

Electron configuration: [Rn] 5f³ 6d¹ 7s²
Electrons per shell: K2 L8 M18 N32 O21 P9 Q2
Oxidation states: 6, 5, 4, 3, 2, 1
Electronegativity (Pauling): 1.38
Atomic radius: Not available
Covalent radius: 196±7 pm
Molar ionization energies: 1st: 597.6 kJ·mol⁻¹ 2nd: 1420 kJ·mol⁻¹ 3rd: 1900 kJ·mol⁻¹ 4th: 3145 kJ·mol⁻¹
Thermal conductivity: 27.5 W·m⁻¹·K⁻¹
Molar heat capacity: 27.665 J·mol⁻¹·K⁻¹
Crystal structure: Orthorhombic
CAS number: 7440-61-1

Property source: Wikipedia — Uranium, adapted from the Nuclides App snapshot. Quoted conditions and qualifiers are retained.

Sources and interpretation

Snapshot exported 24 October 2026 from the element assets used by Nuclides. Properties are a reference compilation, not a new evaluation. Missing values are shown as “Not available”. Density and phase depend on temperature, pressure and allotrope; retained conditions are part of the quoted property.

Atomic weight is dimensionless. Parentheses give uncertainty in the last quoted digits. A single integer in square brackets is an isotope mass number, not a standard atomic weight. The snapshot can differ from current evaluations; consult CIAAW standard atomic weights and the IUPAC periodic table for current values and conventions.

Element properties in the App snapshot are adapted from Wikipedia. Each element page links to its source article; text adaptations are available under CC BY-SA 4.0. No third-party images are included.

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