History and Uses:

Uranium was discovered by Martin Heinrich Klaproth, a German chemist, in the mineral pitchblende (primarily a mix of uranium oxides) in 1789. Although Klaproth, as well as the rest of the scientific community, believed that the substance he extracted from pitchblende was pure uranium, it was actually uranium dioxide (UO2). After noticing that 'pure' uranium reacted oddly with uranium tetrachloride (UCl4), Eug�ne-Melchoir P�ligot, a French chemist isolated pure uranium by heating uranium dioxide with potassium in a platinum crucible. Radioactivity was first discovered in 1896 when Antoine Henri Becquerel, a French physicist, detected it from a sample of uranium. Today, uranium is obtained from uranium ores such as pitchblende, uraninite (UO2), carnotite (K2(UO2)2VO4�1-3H2O) and autunite (Ca(UO2)2(PO4)2�10H2O) as well as from phosphate rock (Ca3(PO4)2), lignite (brown coal) and monazite sand ((Ce, La, Th, Nd, Y)PO4). Since there is little demand for uranium metal, uranium is usually sold in the form of sodium diuranate (Na2U2O7�6H2O), also known as yellow cake, or triuranium octoxide (U3O8).

Since it is naturally radioactive, uranium, usually in the form of uranium dioxide (UO2), is most commonly used in the nuclear power industry to generate electricity. Naturally occurring uranium consists of three isotopes: uranium-234, uranium-235 and uranium-238. Although all three isotopes are radioactive, only uranium-235 is a fissionable material that can be used for nuclear power.

When a fissionable material is struck by a neutron, its nucleus can release energy by splitting into smaller fragments. If some of the fragments are other neutrons, they can strike other atoms and cause them to split as well. A fissionable material, such as uranium-235, is a material capable of producing enough free neutrons to sustain a nuclear chain reaction.