ElementsWhat is plutonium?
Plutonium is a radioactive, silvery metal made in nuclear reactors. Only traces occur in nature.
What is plutonium used for?
Nuclear weapons, fuel for some reactors, and long-lasting heat and power sources for space probes.
Where the name comes from
From Pluto, following the pattern of uranium and neptunium.
Key facts
- Symbol
- Pu
- Atomic number
- 94
- Atomic mass
- 244.06420 u
- Family
- Actinide
- Period
- 7
- Group
- none (f-block)
- Block
- f
- State at room temperature
- Solid
- Melting point
- 639.9 °C (913 K, 1,184 °F)
- Boiling point
- 3,228 °C (3,501 K, 5,842 °F)
- Density
- 19.84 g/cm³
- Electrons per shell
- 2, 8, 18, 32, 24, 8, 2
- Electron configuration
- [Rn]7s2 5f6
- Common oxidation states
- +6, +5, +4, +3
- Electronegativity (Pauling)
- 1.28
- First ionisation energy
- 6.06 eV
- Electron affinity
- no value
- Atomic radius (van der Waals)
- 243 pm
- Discovered
- 1940
Place in the periodic table
Plutonium is element number 94. 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 neptunium (93), and just after it comes americium (95).
Family: Actinides.
Physical properties
At room temperature plutonium is a solid. It melts at 639.9 °C and boils at 3,228 °C, so it stays liquid over a range of 2,588 degrees. Its density is 19.84 grams per cubic centimetre, so a one-litre block would weigh about 19.84 kilograms. By density it ranks 6th among the 96 elements with a measured value.
Inside the atom
An atom of plutonium has 94 protons in its nucleus and, when neutral, 94 electrons around it. The electrons are arranged in 7 shells: 2, 8, 18, 32, 24, 8, 2. The outermost shell holds 2 electrons. Written in full, the electron configuration is [Rn]7s2 5f6.
Its electronegativity on the Pauling scale is 1.28. 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 6.06 electronvolts (about 585 kilojoules per mole). One mole of plutonium weighs 244.06420 grams, so a single gram contains about 2.47 × 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 plutonium 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.