Uranium is a radioactive element, atomic number 92. It is a dense, metallic substance, and its compounds are highly toxic.
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Uranium (U) is a heavy, naturally radioactive, metallic element (atomic number 92). Its two principally occurring isotopes are uranium-235 and uranium-238. Uranium-235 is indispensable to the nuclear industry because it is the only isotope existing in nature, to any appreciable extent, that is fissionable by thermal neutrons. Uranium-238 is also important because it absorbs neutrons to produce a radioactive isotope that subsequently decays to the isotope plutonium-239, which also is fissionable by thermal neutrons.
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Uranium is a radioactive element. It is a dense, metallic substance, and its compounds are highly toxic.