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Element Fact
Americium is one of the few radioactive elements that find its use in homes as a smoke detector.

Plutonium, Pu

plutonium sample

Atomic number: 94
Atomic mass: [244] (no stable nuclide)
Natural abundance: -
239Pu (239.052157) - *%
244Pu (244.064198) - *%

History and Production

The name is derived from the planet Pluto. It was the second transuranium element to be discovered, after neptunium. It was first produced (238Pu) by G.T. Seaborg, E.M. McMillan, J.W. Kennedy and A. Wahl, from bombardment of 238U with deuteron (2H) in a cyclotron at Berkeley, California in 1940. The metal can be prepared by reduction of trifluoride with calcium or magnesium. The isotope 239Pu is by far the most important, produced in large quantities in breeder nuclear reactors. It is used to generate electricity and also as an explosive ingredient in nuclear weapons.

Physical Data

It has a silvery-white appearance and gives a slight yellow tarnish when exposed to air. It exhibits six allotropic forms having various crystalline structures. The element is highly radiologically toxic which can be adsorbed by bone marrow.

Interatomic distance: 302.6 pm (gamma form)
Melting point: 640C
Boiling point: 3228C
Thermal conductivity/Wm-1K-1: 6.74 (27C)
Density/kgm-3: 19840 (a, 25C)

Standard Thermodynamic Data (atomic gas)

Enthalpy of formation: -
Gibbs free energy of formation: -
Entropy: -
Heat capacity: -

Electronic data

Electronic configuration: [Rn] 5f6 7s2
Term symbol: 7F0
Electron affinity: -   Electronegativity (Pauline): 1.3
Ionization energy (first, second, third): 581.440, -, - kJ/mol

Chemical properties

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