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Uranium - U General Information Discovery Uranium was discovered by M.H. Klaproth in 1789 in Berlin, Germany, and isolated by E.M. Péligot in Paris, France in 1842. Appearance Uranium is a radioactive, silvery metal. Source Uranium occurs naturally in several minerals such as pitchblende, uraninite and carnotite. It is also found in phosphate rock and monazite sands. It can be prepared by reducing uranium halides with Group 1 or Group 2 metals, or by reducing uranium oxides with calcium or carbon at high temperatures. Uses Uranium is of great importance as it provides us with nuclear fuel. Uranium-235 is the only naturally occurring fissionable fuel (can sustain a chain reaction) but is of very low abundance. However, in a breeder reactor uranium-238 can capture a neutron and undergo negative beta decay to become Plutonium-239. This synthetic, fissionable element can sustain a chain reaction and the resultant heat is used to create steam to work turbines and generate electrical power. Uranium is the major material from which other synthetic transuranium elements are made, and is used to make nuclear weapons as well as isotopes for peaceful purposes Biological Role Uranium has no known biological role. It is toxic due to its radioactivity. General Information Uranium is malleable, ductile and tarnishes in air. It reacts with acids but not by alkalis. In a finely divided state it is pyrophoric. |
| Physical Information | |||
| Atomic Number | 92 | ||
| Relative Atomic Mass (12C=12.000) | 238.03 | ||
| Melting Point/K | 1405 | ||
| Boiling Point/K | 4018 | ||
| Density/kg m-3 | 18950 (293K) | ||
| Ground State Electron Configuration | [Rn]5f36d17s2 |
| Key Isotopes | |||||
| nuclide | 234U | 235U | 236U | 238U | |
| atomic mass | 234.04 | 235.04 | 236.05 | 238.05 | |
| natural abundance | 0.005% | 0.720% | 0% | 99.28% | |
| half-life | 2.47x105 yrs | 7x108 yrs | 2.39x107 yrs | 4.51x109 yrs |
| Other Information | ||
| Enthalpy of Fusion/kJ mol-1 | 15.5 | |
| Enthalpy of Vaporisation/kJ mol-1 | 417.1 | |
| Oxidation States | ||
| main | U+6 | |
| others | U+2, U+3, U+4, U+5 | |
| Ionisation Energies/kJ mol-1 | ||
| M - M+ | 584 | |
| M+ - M2+ | 1420 | |
| M2+ - M3+ | ||
| M3+ - M4+ | ||
| M4+ - M5+ | ||
| M5+ - M6+ | ||
| M6+ - M7+ | ||
| M7+ - M8+ | ||
| M8+ - M9+ | ||
| M9+ - M10+ | ||
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