What is Plutonium?
[[File:Pu,94.jpg|thumb|A button of plutonium above a calcium chloride salt cake.]] {{wiktionary}} '''Plutonium''' is the [[chemical element]] with the [[atomic number]] 94 and chemical symbol '''Pu'''. It is a highly [[radioactive]] [[metal]], and is the metal used in most [[nuclear weapon]]s. The chemical element plutonium has some different [[isotopes]]. The most important isotope of plutonium is <sup>239</sup>Pu (or plutonium-239). It takes 24,110 years for half of a sample of plutonium-239 to decay, which is called its [[Half-life (element)|half-life]]. It can be made from natural [[uranium]]. It is [[Nuclear fission|fissile]] and a [[nuclear fuel]]. The isotope that has the longest half-life is <sup>244</sup>Pu (or plutonium-244). Plutonium-244 has a half-life of about 80 million years. The half-life of <sup>244</sup>Pu is long enough that some of this isotope of plutonium is found in very small amounts in nature. Plutonium-238 is used in [[Radioisotope Thermoelectric Generator]]s. Like other [[transuranium element]]s, plutonium can react with water, oxygen, carbon, [[halogen]]s, nitrogen, and [[silicon]]. It forms [[oxide]]s and [[hydride]]s in moist air, causing the plutonium sample to expand by up to 70%. Plutonium from the expanding sample can flake off and catch fire at room temperature. Plutonium is also [[toxic]], although it is less toxic than many people think. The reactivity and toxicity of plutonium make it difficult to handle. Fresh plutonium has a silvery bright colour but takes on a dull grey, yellow or olive green tarnish when exposed to air. {{chem-stub}} {{Periodic Table}} [[Category:Actinides]] [[Category:Synthetic elements]]