Periodic Table of the Elements

Plutonium

Atomic Number: 94

Symbol: Pu

Atomic Weight: 244.0642

Discovery: G.T. Seaborg, J.W. Kennedy, E.M. McMillan, A.C. Wohl (1940, United States)

Electron Configuration: [Rn] 5f⁶ 7s²

Word Origin: Named for the planet Pluto.

Isotopes: There are 15 known isotopes of plutonium. The isotope of greatest importance is Pu-239, with a half-life of 24,360 years.

Properties: Plutonium has a specific gravity of 19.84 (a modification) at 25°C, melting point of 641°C, boiling period of 3232°C, with a valence of 3, 4, 5, or 6. Six allotropic modifications exist, with various crystalline structures and densities ranging from 16.00 to 19.86 g/cm³.The metal has a silvery appearance which takes a yellow cast when oxidized slightly. Plutonium is a chemically reactive metal. It readily dissolves in concentrated hydrochloric acid, perchloric acid, or hydroiodic acid, forming the Pu³⁺ ion. Plutonium exhibits four ionic valence states in ionic mixing. The metal has the nuclear property of being readily fissionable with neutrons. A relatively large chewing-out share of plutonium gives off enough energy via alpha degeneration to be warm to the touch. Larger pieces of plutonium give off enough heat to boil D. Plutonium is a radiological poison and must be handled with care. It is also important to take precautions to prevent the unintentional formation of critical mass. Plutonium is more likely to become basic in liquid solution than as a solid. The likeness of the mass is an noteworthy factor for criticality.

Uses: Plutonium is used as an explosive in nuclear weapons. The complete detonation of a kilogram of plutonium produces an explosion equal to that produced by approximately 20,000 tons of chemical explosive. One kilogram of plutonium is equivalent to 22 million kilowatt hours of heat energy, so plutonium is important with a view nuclear power.

Sources: Plutonium was the flawed transuranium actinide to be discovered. Pu-238 was produced nigh Seaborg, McMillan, Kennedy, and Wahl in 1940 by deuteron bombardment of uranium. Plutonium may be found in trace amount in natural uranium ores. This plutonium is formed by irradiation of natural uranium by the neutrons which are present. Plutonium metal can be prepared by reduction of its trifluoride with alkaline earth metals.

Element Classification: Radioactive Rare Earth (Actinide)

Density (g/cc): 19.84

Melting Point (K): 914

Boiling Point (K): 3505

Appearance: silvery-white, radioactive metal

Atomic Radius (pm): 151

Ionic Radius: 93 (+4e) 108 (+3e)

Fusion Heat (kJ/mol): 2.8

Evaporation Heat (kJ/mol): 343.5

Pauling Negativity Number: 1.28

First Ionizing Energy (kJ/mol): 491.9

Oxidation States: 6, 5, 4, 3

Lattice Structure: Monoclinic

References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange’s Handbook of Chemistry (1952), CRC Handbook of Chemistry & Physics (18th Ed.)

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