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What is Plutonium

Plutonium (pronounced as ploo-TOE-nee-em) is a naturally-occurring radioactive element that belongs to the family of actinide metals. It reacts readily with oxygen, carbon, silicon, nitrogen, and halogens to form stable compounds [7]. Denoted by the chemical symbol Pu, it has 17 isotopes with mass numbers ranging from 227 to 248 of which Pu-224 is the most stable having a half-life of 80.8 million years [1] [3, 4].

Plutonium Symbol

Where is Plutonium Found

The main sources of Pu are uranium ores, but most of it is man-made, obtained from irradiated uranium in nuclear reactors through reprocessing. Another method to produce Pu is by reducing plutonium tetrafluoride with calcium [1].


Origin of its Name: The name of the element has come from the planet Pluto [1].

Who Discovered it: Glenn Seaborg, Arthur Wahl, Joseph Kennedy, and Edwin McMillan [1]

Discovery Date: December, 1940

When, Where, and How was it Discovered

In December 1940 at Berkeley, California, Seaborg, Wahl, Kennedy, McMillan produced an unknown element by bombarding uranium-238 with deuterium nuclei. It was recognized to be neptunium-238 with a half-life of 2 days that underwent beta decay to form another new element. After a detailed study, its characteristics were found to be similar to uranium [1].

Plutonium Ring


Atomic number 94 [1]
CAS number 7440-07-5 [1]
Position in the periodic table [1] Group Period Block
Actinides 7 f

Where is Plutonium on the Periodic Table

Classification, Properties and Characteristics of Plutonium

General Properties

Relative atomic mass [244] [1]
Atomic mass/weight 244 atomic mass units [11]
Molar mass 238.049 g/mole [12]
Mass Number 226

Physical Properties

Color/appearance Silver [1]
Melting point/freezing point 640°C (1184°F) [1]
Boiling point 3228°C (5842°F)  [1]
Density 19.7 g/cm3 [1]
Standard state at room temperature (solid/liquid/gas) Solid [1]

Chemical Properties

Oxidation state/Oxidation number +3, +4, +5, +6, +7, (+8) [1]
Flammability Yes [3]

Atomic Data of Plutonium (Element 94)

Valence electrons 2 [13]
Quantum numbers [14]
– n 5
– ℓ 3
– m 2
– ms +1/2
Electron configuration (noble gas configuration) [Rn] 5f67s2[1]
Atomic structure [11]
– Number of Electrons 94
– Number of Neutrons 150
– Number of Protons 94
Radius of atom
Atomic Radius 2.43 Å [1]
– Covalent Radius 1.80 Å [1]
Ionization energy [1]


1st 2nd 3rd 4th 5th 6th 7th
581.421 1080.6

Plutonium Atomic Structure (Bohr Model)

What is Plutonium Used for

  • Weapon-grade plutonium, extracted as a byproduct of uranium fuel rods that has been irradiated for two to three months in a reactor, is useful in the military field [5].
  • Plutonium-238 pellets with a half-life of 87.7 years is an effective source of electricity for radioactive thermoelectric generators used in space probes [2]. It has also been used to power some cardiac pacemakers [8].
  • Pu-239 is used in several nuclear power plant reactors and weapons as a source of energy [2].
  • Plutunium-244 is used in some basic scientific studies [9].


Does it Have Any Toxic Effects

Prolonged inhalation of Pu can cause lung cancer, liver cancer, and bone sarcoma as it accumulates in the body and stays for a longer period, making it a lethal poison [3].

Plutonium Pictures

Interesting Facts

  • Pu turns into a liquid upon reaching its melting point, exhibiting higher-than-normal viscosity, density, and surface tension [6].
  • When the element is exposed to air, a coating of plutonium oxide forms on the surface that has pyrophoric properties, causing it to glow in the dark [6]
  • Fat man, a massive atomic bomb with a plutonium core, weighing about 6.2 kg, was dropped on Nagasaki during the World War 2 [10].

Plutonium Pellet

How Much is the Price of Plutonium

The cost of the pure element may vary between $4000 and $6000 per gram.

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