Plutonium

Plutonium is a silvery radioactive metal named after the planet Pluto.

Plutonium
Properties
Atomic symbol	Pu
Atomic number	94
Classification	Metallic
Atomic mass	244 amu
Other Information
Date of discovery	1940
Name of discoverer	G.T.Seaborg, A.C.Wohl and J.W.Kennedy
Name origin	Named after the planet Pluto.
Uses	Fuel for nuclear reactors, as well as nuclear weapons.
Obtained from	Found in small doses in some uranium ores. Also manufactured by bombarding uranium with neutrons.

History

Plutonium is a man-made element discovered in 1940 after uranium-238 was bombarded with neutrons in a device called a cyclotron. Plutonium-239, as well as uranium-235 and uranium-233, are among the few materials whose atoms can be split (or fissioned) to create a nuclear explosion, which releases massive amounts of energy almost instantaneously.

Applications

Plutonium is used in the manufacture of nuclear weapons. It was first made in significant quantities during the World War II Manhattan Project. While plutonium-239 (the isotope used in weapons) is produced in all uranium-fueled nuclear reactors, it generally cannot be used for weapons production because small amounts of plutonium-240 gradually build up, "poisoning" the plutonium-239.

Plutonium can also be used as a fuel in certain types of nuclear reactors where the fission process is controlled so that large quantities of energy are released more slowly to make steam and produce electricity. The split plutonium atoms become lighter elements such as the life-threatening cesium-137 and strontium-90, many of which are highly radioactive. These "fission products" are radioactive waste, although some are useful for nuclear medicine and other purposes.

Plutonium-238 decays more rapidly than plutonium-239, which generates larger amounts of heat. So much heat that it can glow red-hot if insulated. Small pieces of Pu-238 have been used in U.S. spacecraft to keep sensitive components warm for years at a time.