92
U
Uranium
238
Uranium (U)
ActinidePeriod 7f-block-blockRadioactive
Uranium is a chemical element with symbol U and atomic number 92. It is a silvery-white metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons.
Latin name: Uranium
Atomic Number
92
Atomic Mass
238 g/mol
Phase (STP)
Solid
Electron Config.
[Rn] 5f³ 6d¹ 7s² (commonly [Rn] 5f³ 6d¹ 7s²)
General
SymbolU
Atomic Number92
Atomic Mass238 g/mol
CategoryActinide
Period7
Blockf-block
Electron Configuration[Rn] 5f³ 6d¹ 7s² (commonly [Rn] 5f³ 6d¹ 7s²)
Valence Electrons6
Coloursilvery-gray metallic
CAS NumberCAS7440-61-1
Physical Properties
Phase (STP)Solid
Density19.1 g/cm³
Melting Point1132.15°C · 2069.87°F · 1405.30 K
Boiling Point4130.85°C · 7467.53°F · 4404.00 K
Atomic Properties
Atomic Radius240 pm
Electronegativity1.38 Pauling
Ionization Energy597 kJ/mol
Oxidation States+6, +5, +4, +3, +2
Ion ChargeU3+/U4+/U6+
Thermodynamic
Molar Heat27.665 J/(mol·K)
Crystal Structure
Crystal Structureorthorhombic (α-U)
Nuclear & Hazards
RadioactiveYes
Half-life4.468×10^9 years (U-238)
Abundance
In Universe0.00000001%
In Earth's Crust0.0002%
Discovery & History
Discovery Year1789
Discovered ByMartin Heinrich Klaproth
Country of DiscoveryGermany
Isotopes of Uranium
| Isotope | Abundance | Half-life | Decay |
|---|---|---|---|
| U-234 | 0.0054% | 2.455 × 10⁵ years | α |
| U-235 | 0.7204% | 7.038 × 10⁸ years | α |
| U-236 | — | 2.342 × 10⁷ years | α |
| U-238 | 99.2742% | 4.468 × 10⁹ years | α |