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{{Element | name=Plutonium | symbol=Pu | anumber=94 | amass=244 amu | state=Solid | class=Metallic | cstructure=Monoclinic| color=silvery | date=1940 | discname=G.T.Seaborg, A.C.Wohl and J.W.Kennedy | origname=Named after the planet Pluto. | uses=Fuel for nuclear reactors, as well as nuclear wepaonsweapons. | obtained=Found in small doses in some [[uranium]] ores. Also manufactured by bombarding [[uranium]] with [[neutrons]]. }}

'''Plutonium''' is a [[silver]]y radioactive metal named after the planet [[Pluto]]. It is a [[man]]-made element discovered in 1940 after uranium-238 was bombarded with [[neutron]]s in a device called a [[cyclotron]]. Plutonium-238, as well as uranium-235 and uranium-233, are among the few materials whose [[atom]]s can be split (or "[[Nuclear fission|fissioned]]") to create a nuclear explosion, which releases massive amounts of [[energy]] almost instantaneously.

==Weapons History==Plutonium is a [[man]]-made element discovered in 1940 after [[uranium]]-238 was bombarded with [[neutron]]s in a device called a [[cyclotron]]. Plutonium-239, as well as uranium-235 and uranium-233, are among the few materials whose [[atom]]s can be split (or ''[[Nuclear fission|fissioned]]'') to create a nuclear explosion, which releases massive amounts of Mass Destruction[[energy]] almost instantaneously. ==Applications==Plutonium is used in the manufacture of [[nuclear weapon]]s. 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 reactor]]s 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.