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{{Element | name=Uranium | symbol=U | anumber=92 | amass=238.02891 amu | state=Solid | class=Metallic | cstructure=Orthorhombic| color=metallic grey, reacts slowly with oxygen and rapidly with water. | date=1789 | discname=Martin J. Klaproth | origname=From the planet Uranus. | uses=For many centuries it was used as a pigment for glass. Now it is used as a fuel in nuclear reactors and in nuclear weapons. Depleted Uranium uranium is used in casings the kinetic penetrators of armor -piercing artillery shells, armor plating on tanks , and as ballast in the wings of some large aircraft. | obtained=Primary uranium bearing ores are uraninite, autunite, carnotite, samarskite and torbernite. }}'''Uranium''' (U) is a heavy, naturally [[radioactive]], [[metal]]lic [[element]] with an [[atomic number]] of 92.

'''Uranium''' (U) is a heavy, naturally [[radioactive]], [[metal]]lic [[element]] with an [[atomic number]] of 92. ==Isotopes==Its two principally occurring [[isotope]]s are uranium-235 and uranium-238. Uranium-235 is indispensable to the nuclear industry because it is the only isotope existing Their respective proportions play a large role in nature that is fissionable by thermal [[neutron]]s. 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 [[fission]]able by thermal neutronsits use.

"Depleted" Uranium -238 is the dominant isotope, making up 99.3% (mass basis) of natural uranium. This percentage varies little between mines. In nuclear reactors, it plays an important role by absorbing neutrons to produce a [[radioactive]] isotope which subsequently decays to the isotope [[plutonium]]-239, which is [[fission]]able by the thermal neutrons present in conventional light water reactors. Uranium-235 is indispensable to the nuclear industry because it is the only isotope existing in nature that is fissionable by the thermal [[neutron]]s. It makes up 0.7% of natural uranium. In a process called ''enrichment'', the proportion of uranium-235 is increased by small amounts in hundreds of steps to produce fuel of 2% to 5% uranium-235. This, unlike natural uranium, can sustain a nuclear chain reaction in a light water reactor. ==Applications==''Depleted uranium'' is a by-product of enriched uranium, a mixture of the 235 and 238 isotopes with a lower concentration of uranium-235 than in nature. It is one of the densest materials known to man; . As such, the United States uses it has been used for bullets and artillery shells, tank armor, ballast, and gyroscopes. There are no known serious health risks stemming from external exposure to it.,<ref>http://www.sciencedaily.com/releases/2005/07/050724094117.htm</ref><ref>http://web.ead.anl.gov/uranium/guide/depletedu/health/index.cfm</ref>however it can still cause heavy metal poisoning when ingested, in the same manner as commonplace elements such as [[lead]], [[mercury]], and [[cadmium]]. Uranium compounds display a wide range of colors and have been used for coloring ceramic glazes and glass.