Plutonium (Pu)
Actinide · f-block · period 7
Silvery metal that yellows with oxidation; warm to the touch from its own decay.
Plutonium (symbol Pu) is chemical element number 94, a actinide in the actinide series (f-block), period 7 of the periodic table. Its standard atomic weight is (244) and its electron configuration is [Rn] 5f6 7s2. At room temperature it is a solid, and it is radioactive. Named after Pluto, continuing the Uranus–Neptune sequence.
Properties
| Atomic number | 94 |
|---|---|
| Atomic mass | (244) |
| Category | Actinide |
| Block | f-block |
| Group · Period | f-block series · 7 |
| Electron configuration | [Rn] 5f6 7s2 |
| Electrons per shell | 2, 8, 18, 32, 24, 8, 2 |
| State at 25 °C | solid |
| Melting point | 912.5 K |
| Boiling point | 3505 K |
| Density | 19.85 g/cm³ |
| Electronegativity (Pauling) | 1.28 |
| Radioactive | Yes — no stable isotope |
| Origin | decay |
| Discovered | 1940 · Seaborg, McMillan, Kennedy & Wahl |
Key facts about Plutonium
- Named after Pluto, continuing the Uranus–Neptune sequence.
- The core of the bomb dropped on Nagasaki was plutonium.
- It has six different solid forms and is one of the strangest metals to work with.
- Plutonium-238 has powered deep-space probes like Voyager and the Mars rovers for decades.
What Plutonium is used for
Nuclear weapons, reactor fuel (MOX), radioisotope power sources for spacecraft and remote stations.
Where it sits in the periodic table
Plutonium is in the actinide series, period 7, of the f-block. Its electron configuration [Rn] 5f6 7s2 means its outermost shell holds 2 electrons, which is what places it here and explains much of its chemistry. See Plutonium on the interactive table →
Plutonium — frequently asked questions
What is Plutonium used for?
Nuclear weapons, reactor fuel (MOX), radioisotope power sources for spacecraft and remote stations.
Is Plutonium radioactive?
Yes. Plutonium has no stable isotope, so every form of it is radioactive.
What is the electron configuration of Plutonium?
Plutonium has the electron configuration [Rn] 5f6 7s2, which is 2, 8, 18, 32, 24, 8, 2 electrons per shell.
What group and period is Plutonium in?
Plutonium is in the actinide series (f-block), period 7, in the f-block. Its outer shell holds 2 electrons.
Who discovered Plutonium?
Plutonium was discovered in 1940 by Seaborg, McMillan, Kennedy & Wahl.