ElementsWhat is uranium?
Uranium is a heavy, silvery, weakly radioactive metal. It is the heaviest element found in useful amounts in nature.
What is uranium used for?
Fuel for nuclear power stations. Also nuclear weapons, and the dense metal is used for shielding and ballast.
Where the name comes from
From the planet Uranus, discovered eight years before the element.
Key facts
- Symbol
- U
- Atomic number
- 92
- Atomic mass
- 238.0289 u
- Family
- Actinide
- Period
- 7
- Group
- none (f-block)
- Block
- f
- State at room temperature
- Solid
- Melting point
- 1,135 °C (1,408 K, 2,075 °F)
- Boiling point
- 4,131 °C (4,404 K, 7,468 °F)
- Density
- 18.95 g/cm³
- Electrons per shell
- 2, 8, 18, 32, 21, 9, 2
- Electron configuration
- [Rn]7s2 5f3 6d1
- Common oxidation states
- +6, +5, +4, +3
- Electronegativity (Pauling)
- 1.38
- First ionisation energy
- 6.194 eV
- Electron affinity
- no value
- Atomic radius (van der Waals)
- 240 pm
- Discovered
- 1789
Place in the periodic table
Uranium is element number 92. It sits in period 7 (row 7) of the periodic table, in the separate row of actinides drawn below the main table, and belongs to the f-block. Just before it comes protactinium (91), and just after it comes neptunium (93).
Family: Actinides.
Physical properties
At room temperature uranium is a solid. It melts at 1,135 °C and boils at 4,131 °C, so it stays liquid over a range of 2,996 degrees. Its density is 18.95 grams per cubic centimetre, so a one-litre block would weigh about 18.95 kilograms. By density it ranks 9th among the 96 elements with a measured value.
Inside the atom
An atom of uranium has 92 protons in its nucleus and, when neutral, 92 electrons around it. The electrons are arranged in 7 shells: 2, 8, 18, 32, 21, 9, 2. The outermost shell holds 2 electrons. Written in full, the electron configuration is [Rn]7s2 5f3 6d1.
Its electronegativity on the Pauling scale is 1.38. This number shows how strongly an atom pulls shared electrons towards itself: fluorine, the strongest, is 3.98. Removing one electron from an atom takes 6.194 electronvolts (about 598 kilojoules per mole). One mole of uranium weighs 238.0289 grams, so a single gram contains about 2.53 × 1021 atoms.
The ring picture is a simple model that only counts the electrons in each shell. Real atoms do not look like this.
Next steps
- Work out the weight of a compound that contains uranium with the molar mass calculator.
- Compare it with every other element in the sortable list.
- Test yourself with the symbol quiz.
Figures on this page are from PubChem (U.S. National Library of Medicine), as downloaded on 11 November 2026. See About and data sources.