|Atomic Symbol||Atomic symbol::U|
|Atomic Number||Atomic number::92|
|Atomic Weight||Atomic weight::238.0 g/mol|
|Group, Period, Block||3, 7, f|
|Electron configuration||[Rn] 5f3 6d1 7s2|
|Electrons per shell||2, 8, 18, 32, 21, 9, 2|
|CAS number||CAS number::7440-61-1|
|Melting point||Melting point::1408 K|
|Boiling point||Boiling point::4403 K|
|Isotopes of Uranium|
|All properties are for STP unless otherwise stated.|
Uranium is a chemical element that is part of the actinide series in the Periodic Table of the Elements. Its atomic number is 92 and its symbol is U. It was first discovered in 1896 by Martin Klaproth. It is a highly radioactive and toxic element. It mainly used in nuclear energy generators and in nuclear weapons.
Uranium is a dense, hard and malleable metal. It has a silvery-white color, and is slightly paramagnetic. It also has a low level of radioactivity. It is highly reactive and the air will coat uranium with a sheet of oxide. Cold water will also react with uranium when the uranium is finely divided. Acids will dissolve uranium, but alkalines will not affect uranium.  It has a melting point of 1132 °C and a boiling point of 3818 °C. 
There are twenty-three isotopes of uranium, and all of them are radioactive. This list of isotopes includes U218 through U242. However, only U234, U235, and U238 occur naturally. The fact that uranium isotopes are radioactive means that the nucleus in uranium is unstable and decays into other elements by emitting particles. This process is called radioactive decay and involves the emission of either alpha or beta particles until the element takes a more stable form. This process also emits electromagnetic radiation called gamma radiation. For example, Uranium-234 will decay into Thorium-230 which will decay into Radium-226 and so on until it reaches a stable form. 
Occurrencesrocks and soil. The uranium that ends up in water is usually dissolved from the dirt and the rocks that water runs over. Overall, the concentration of uranium in the environment is extremely low. Because it is highly reactive, it is impossible to find uranium in its pure elemental form.
As already stated, there are only three isotopes of uranium that occur naturally: U234, U235, and U238. Based on weight, uranium 238 occurs the most naturally with 99.2745% of natural uranium composed of this isotope. Uranium 234 occurs in 0.0055%, and uranium 235 occurs in 0.720%.  Uranium was once obtained mining in underground mines and open pits. In recent years, newer techniques have been developed to prevent the spread of radiation such as leach mining. This process involves injecting solutions into underground deposits to dissolve uranium. Because of these improved methods, most mines in America have shut down, and America imports most of its uranium.
There are many uses for uranium, but the majority of uranium is used in nuclear power stations and nuclear weapons. It has some other uses, but the uranium can usually be replaced by safer substances. Both the plutonium bomb and the uranium bomb require uranium-235 to create a nuclear reaction.  Uranium is also used widely in nuclear reactors. These reactors range in a variety of uses including the production of electricity, the production of nuclear weapons, and the powering of military ships and submarines. The depleted uranium can also be used to produce armor piercing bullets and missiles, and can be developed into ballasts for ships.  Depleted uranium can also be found in inertial guidance devices, gyro compasses, counterweights for aircraft, and as ballast for missile reentry vehicles. It is used in hig energy X-rays and its nitrate can be used as a photographic toner. However, uranium is often too difficult to use in most commercial products due to its high levels of toxicity and radioactivity. It is available commercially at $200 dollars a kilogram. Today, Kazakhstan is the largest supplier of Uranium followed by Canada.
Uranium was first discovered in 1789 by Martin Klaproth. Besides its usefulness in scientific study, the only real use of uranium was in the coloring of glass and ceramic products. Its radioactive properties were first discovered in 1896 by Henri Becquerel. He did not realize the significance of his discovery but Marie Curie, one of his students, correctly interpreted his results and called the emission of particles radioactivity. Marie Curie and her husband went on to discover the element radium and uranium was required to extract this new element. The demand for radium and Madam Curie's work in radioactivity sparked the mining and study of uranium. In Germany Otto Hahn performed the first nuclear fission, but the world was on the verge of World War II. Enrico Fermi and his team built the first nuclear reactor at the University of Chicago. The U.S. feared nuclear technology falling into the wrong hands, and the several nuclear scientists from all over the world were recruited into the Manhattan Project. This resulted the first nuclear exposion at the Trinity Test site in New Mexico and the nuclear destruction in Nagasaki and Hiroshima. After the war, uranium was used in nuclear technology for more peaceful purposes. The development of nuclear power sources quickly progressed and became a source of power for countries all over the world.
- The Elements C. R. Hammond, Publisher, Date
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