Uranium
Element 92 · Actinide
Uranium is a heavy, silvery metal that is slightly paramagnetic and about 70 percent denser than lead. Natural uranium is mostly uranium-238 with 0.7 percent uranium-235, the fissile isotope that sustains chain reactions. It displays a wide range of oxidation states, with +6 dominating in compounds such as uranyl salts. Beyond energy and historical weapons use, depleted uranium serves in radiation shielding and counterweights, and uranium compounds once colored glass and ceramics.
Key facts
| Atomic number | 92 |
|---|---|
| Atomic weight | 238.03 |
| Category | Actinide |
| Group / Period | — / 7 |
| Block | f |
| Electron configuration | [Rn] 5f3 6d1 7s2 |
| Common oxidation states | +6, +4, +5, +3 |
| State at STP | Solid |
| Electronegativity | 1.38 |
| Density | 19.1 g/cm3 |
| Melting point | 1132 °C |
| Boiling point | 4131 °C |
Occurrence
Uranium is a fairly common element, more abundant than silver in the Earth's crust. Major deposits are mined in Kazakhstan, Canada, Australia, and Namibia, chiefly from minerals like uraninite.
Applications
Fuel for nuclear power reactors (enriched uranium-235)
Depleted uranium in radiation shielding and armor
Historical: coloring for glass and ceramic glazes
Common compounds
- Uranium dioxide (UO2)
- Uranium hexafluoride (UF6)
- Uranyl nitrate (UO2(NO3)2)
Uranium was discovered in 1789 by Martin Heinrich Klaproth, who named it after the planet Uranus, discovered eight years earlier.
Data source: IUPAC standard atomic weights 2021