94Pu244.064
Plutonium
Actinoids · solid at STP · Block F
About
Plutonium is a radioactive actinide metal with a silvery-gray appearance that tarnishes in air. Its isotope plutonium-239 is the primary fissile material used in most modern nuclear weapons. It is also used as a fuel in some nuclear reactors and as a long-lived power source for deep space probes like Cassini and New Horizons, in the form of radioisotope thermoelectric generators (RTGs).
Atomic Properties
Atomic Number94
Atomic Weight244.064 u
Neutrons (common)150
Electron Configuration[Rn] 5f⁶ 7s²
Full Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁶ 5f⁶ 7s²
Electrons per Shell2, 8, 18, 32, 24, 8, 2
Electronegativity1.28
Oxidation States+7, +6, +5, +4, +3
Covalent Radius187 pm
Ionic Radius100 pm
Periodic Table Position
Group3
Period7
BlockF
Chemical SeriesActinoids
Physical Properties
State at STPsolid
Appearancesilvery-white, tarnishes to a dull gray, olive green, or brown
Crystal Structuremonoclinic
Magnetic Orderingparamagnetic
Speed of Sound2,260 m/s
Poisson Ratio0.21
Thermal Properties
Melting Point912.5 K
Boiling Point3,505 K
Thermal Expansion0 1/K
Thermal Conductivity6.74 W/(m·K)
Specific Heat0.13 J/(g·K)
Molar Heat31.73 J/(mol·K)
Heat of Fusion2.82 kJ/mol
Heat of Vaporization333.5 kJ/mol
Abundance
In Earth's Crust0 ppm
Discovery
Discovered byGlenn T. Seaborg, Arthur Wahl, Joseph W. Kennedy, Edwin McMillan
Discovery Year1,940
Occurrencesynthetic
CAS Number7440-07-5
Electron Configuration
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6d
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Isotopes of Plutonium
| Symbol ▲ | Mass (u) ▲ | Abundance ▲ | Half-life ▲ | Decay Mode ▲ |
|---|---|---|---|---|
| 238Pu | 238.049550 | — | 87.7 y | Alpha Decay, Spontaneous Fission |
| 239Pu | 239.052160 | Trace | 24.11 ky | Alpha Decay, Spontaneous Fission |
| 240Pu | 240.053810 | — | 6.561 ky | Alpha Decay, Spontaneous Fission |
| 241Pu | 241.056850 | — | 14.329 y | Beta Minus Decay, Alpha Decay |
| 242Pu | 242.058740 | — | 375 ky | Alpha Decay, Spontaneous Fission |
| 244Pu | 244.064200 | Trace | 81.3 My | Alpha Decay, Spontaneous Fission |
Interactive Visualization
Explore the 3D Bohr model of Plutonium in our interactive viewer.
View 3D Model of Plutonium