Uranium vs Plutonium
The two names of the nuclear age: the uranium inside reactors and bombs, and the plutonium made from it.
Side by side
| Property | Uranium | Plutonium |
|---|---|---|
| Symbol | U | Pu |
| Atomic number (Z) | 92 | 94 |
| Atomic mass | 238.03 u | [244] u |
| Category | Actinide | Actinide |
| Group | — | — |
| Period | 7 | 7 |
| Phase at room temp | solid | solid |
| Electron configuration | [Rn] 5f³ 6d¹ 7s² | [Rn] 5f^6 7s^2 |
| Valence electrons | 2 | 2 |
| Atomic radius | 154 pm | 152 pm |
| Electronegativity | 1.38 | 1.28 |
| First ionisation energy | 598 kJ/mol | 585 kJ/mol |
The verdicts
- Bigger atom: Uranium — the lower an element sits in its group, the more shells it wears.
- Greedy electron-taker: Uranium — higher electronegativity means it pulls shared electrons harder.
- Heavier: Plutonium — compare the atomic masses in the table above.
Want the visual version with bars for radius, electronegativity and ionisation energy? Open the interactive compare tool with this pair already loaded.