ELEMENTLE

Element 92 · Actinide

Uranium

Period 7

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.

Three reasons Uranium stands out

  1. 1

    Widely used in nuclear power generation and weaponry.

  2. 2

    Glass containing it glows a vivid bright green under ultraviolet light and was fashionable in Victorian tableware.

  3. 3

    Its energy density is roughly 16,000 times greater than coal, making it extraordinarily efficient as a fuel.

Energy locked inside a heavy nucleus

Uranium’s large nucleus can split after absorbing a neutron, releasing energy and additional neutrons. Controlled chains heat power reactors; uncontrolled ones drive weapons. Natural uranium also records geological time, colors some historic glass, and ultimately supplies the radon that can accumulate in buildings.

Uranium at a glance
Atomic number / protons92
SymbolU
Family (Elementle)Actinide
Classification (PubChem)Actinide
Period7
GroupLanthanide / actinide series
Atomic mass (u)238.0289
Standard stateSolid
Electron configuration[Rn]7s2 5f3 6d1
Reported oxidation states+6, +5, +4, +3
Electronegativity (Pauling)1.38
Atomic radius (pm)240
First ionization energy (eV)6.194
Electron affinity (eV)Not available
Density (g/cm³)18.95
Melting point1408 K (1,134.85 °C)
Boiling point4404 K (4,130.85 °C)
Discovery (PubChem)1789

Values are reference data, not a specification for every temperature, pressure, or allotrope. Unknown properties are left unavailable. Superheavy-element predictions remain uncertain.

Sources & further reading

PubChem: Uranium · Uranium on Wikipedia

The introduction and original editorial story are adapted from Wikipedia contributors via Periodic-Table-JSON. Element descriptions and their adaptations are available under CC BY-SA 3.0. Numerical attributes use the PubChem periodic-table dataset, retrieved September 22, 2026.