Uranium

Uranium has 16 isotopes, all of which are radioactive.   The isotope ²³⁵U is used in nuclear reactors because it can be made to release large amounts of energy to boil water into steam that expands to drive steam turbines that, in turn, drive electrical generators.   One pound of pure fisssionable uranium equals the energy derived from burning 1500 tons of coal.   Depleted uranium; that is, uranium with less than 0.2% of ²³⁵U, which is extremely dense, is used in inertial guidance systems, gyro compasses, shielding material, and ammunition. ^{Lide 4-31}

Uranium was discovered in 1786 in pitchblende ore by Martin Heinrich Klaproth, a German chemist.   It was isolated in 1841 by Peligot, who reduced the anhydrous chloride with potassium.   Uranium is found in pitchblende, uraninite, carnotite, autunite, uranophane, davidite, tobernite, phosphate rock, lignite, and monazite.   Uranium is prepared by reducing uranium halides with alkali or alkaline earth metals, or by reducing uranium oxides by calcium, aluminum, or carbon at high temperatures.   It can also be obtained by electrolysis of KUF₅ or UF₄ dissolved in a molten mixture of CaCl₂ and NaCl.   High purity uranium is prepared by the thermal decomposition of uranium halides on a hot filament. ^{Lide 4-31}