Plutonium (Pu)
Actinide · Radioactive · Synthetic
Plutonium is the most consequential synthetic element — created gram by gram in wartime secrecy, it fuels weapons, reactors and deep-space probes. A lump of it is warm to the touch from its own radioactivity.
Position on the periodic table
Atomic properties
| Atomic number | 94 |
|---|---|
| Atomic mass | 244 amu |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f6 |
| Noble gas shorthand | [Rn] 5f6 7s2 |
| Electrons per shell | 2, 8, 18, 32, 24, 8, 2 |
| Valence electrons (outer shell) | 2 |
| Common oxidation states | +4, +6 |
| Electronegativity (Pauling) | 1.28 |
| Covalent radius (approx.) | 187 pm |
| First ionization energy | 584.7 kJ/mol |
| Electron affinity | -48.3 kJ/mol |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Density | 19.82 g/cm³ |
| Melting point | 639.35 °C (912.5 K) |
| Boiling point | 3231.8 °C (3505 K) |
| Appearance | silvery white, tarnishing to dark gray in air |
| Radioactive | Yes |
| Origin | Synthetic (lab-made) |
Electron configuration of plutonium
Plutonium's ground-state electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f6, usually shortened to [Rn] 5f6 7s2. Its electrons occupy 7 shells (2, 8, 18, 32, 24, 8, 2), placing it in period 7 of the f-block. Explore it interactively in the electron configuration calculator.
Uses of plutonium
- Radioisotope power for space probes and Mars rovers (Pu-238)
- Nuclear weapons (Pu-239)
- MOX reactor fuel
Biological role: None — severely radiotoxic if inhaled.
Occurrence: Trace natural amounts; produced in reactors from uranium.
Common compounds of plutonium
PuO2
Plutonium dioxide
History and discovery
Discovered: 1940 — Glenn T. Seaborg. Name origin: Named after Pluto, continuing the planetary sequence.
Glenn Seaborg's team first made plutonium in late 1940; its existence stayed secret until after World War II.
Safety notes
One of the most strictly controlled materials on Earth.
Educational context only — always follow your school's laboratory rules and never handle chemicals without proper supervision. See our disclaimer.
Practice questions
Quick practice: Plutonium
1. What is the chemical symbol of Plutonium?
2. What is the atomic number of Plutonium?
3. Which category does Plutonium belong to?
4. What is the state of Plutonium at room temperature?
5. Which period of the periodic table is Plutonium in?
Plutonium FAQs
What is the atomic number of plutonium?
Plutonium's atomic number is 94 — every plutonium atom has 94 protons in its nucleus.
What is the symbol for plutonium?
Pu. Named after Pluto, continuing the planetary sequence.
Is plutonium a metal, nonmetal, or metalloid?
Plutonium is classified as a actinide.
What state is plutonium at room temperature?
At about 25 °C, plutonium is a solid. It melts at 639.35 °C.
What is plutonium used for?
Key uses include: radioisotope power for space probes and mars rovers (pu-238); nuclear weapons (pu-239); mox reactor fuel.
Related elements
Keep working with this element
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