About

Uranium is a silvery-gray, weakly radioactive metal and the heaviest naturally occurring element. Its isotope uranium-235 is the primary fuel for nuclear reactors and the main material for the first nuclear weapons. Its very high density also makes depleted uranium (mostly U-238) useful as a counterweight in aircraft and in armor-piercing projectiles. It was once used to color glass.

Atomic Properties

Atomic Number92

Atomic Weight238.029 u

Neutrons (common)146

Electron Configuration[Rn] 5f³ 6d¹ 7s²

Full Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁶ 5f³ 6d¹ 7s²

Electrons per Shell2, 8, 18, 32, 21, 9, 2

Electronegativity1.38

Electron Affinity50.94 kJ/mol

Oxidation States+6, +5, +4, +3

Covalent Radius175 pm

Van der Waals Radius186 pm

Ionic Radius102.5 pm

Periodic Table Position

Group3

Period7

BlockF

Chemical SeriesActinoids

Physical Properties

State at STPsolid

Appearancesilvery-white metallic

Crystal Structureorthorhombic

Magnetic Orderingparamagnetic

Speed of Sound3,155 m/s

Poisson Ratio0.23

Thermal Properties

Melting Point1,405.3 K

Boiling Point4,404 K

Triple Point1,405.3 K

Thermal Expansion0 1/K

Thermal Conductivity27.5 W/(m·K)

Specific Heat0.116 J/(g·K)

Molar Heat27.61 J/(mol·K)

Heat of Fusion9.14 kJ/mol

Heat of Vaporization417.1 kJ/mol

Abundance

In Earth's Crust2.7 ppm

In Ocean0.003 ppm

In Solar System0 ppm

In Human Body0.001 ppm

In Universe0 ppm

Discovery

Discovered byMartin Heinrich Klaproth

Discovery Year1,789

Occurrenceprimordial

CAS Number7440-61-1

Electron Configuration

Energy

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Isotopes of Uranium

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
²³²U	232.037150	—	68.9 y	Alpha Decay, Spontaneous Fission
²³³U	233.039630	—	159.19 ky	Alpha Decay
²³⁴U	234.040950	0.0054%	245.5 ky	Alpha Decay
²³⁵U	235.043930	0.7204%	704 My	Alpha Decay
²³⁶U	236.045560	Trace	23.42 My	Alpha Decay, Spontaneous Fission
²³⁸U	238.050780	99.2742%	4.463 Gy	Alpha Decay, Spontaneous Fission, Double Beta Minus Decay

Interactive Visualization

Explore the 3D Bohr model of Uranium in our interactive viewer.

View 3D Model of Uranium