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Uranium Atomic Symbol

Uranium atomic symbol is U. Atomic number of Uranium is 92.Atomic Weight is 238.0289. Uranium is found in Actinide series and belongs to Radioactive Rare Earth Element. Uranium is discovered by Martin Klaproth.

It has Density of 19.05 g/cc, Melting Point 1405.5 K, Boiling Point 4018 K.

Uranium appears as Silvery-white, dense, ductile and malleable and it is a radioactive metal. 

Atomic radius of Uranium is 138 pm. 

Atomic Volume is 12.5 cc/mol. 

Electronic Configuration of uranium is [Rn] 5f3 6d1 7s2

Oxidation States of Uanium is 6, 5, 4, and 3.



Radiochemistry of uranium:


Uranium Isotopes:

Natural uranium is 99.274 atom % 238U, 0.7205 atom % 235U, and 0.0056 atom % 234U. The 234/238 ratio is exactly the ratio of their half-lives as expected for nuclei in secular equilibrium. The isotope 233U is produced by neutron capture on 232Th, followed by β- decay. 232U is a short-lived (t1/2 =72 y) nuclide that is a contaminant in 233U samples (from fast neutron reactions). The daughters of 232U are hard gama-ray emitters that make working with 232U containing samples difficult. 236,237,239U are produced by neutron captures on 235U and 238U. 236U is long-lived but 237,239U are short-lived and decay to 237Np and 239Pu, respectively.

Metallic Uranium:

Metallicuranium can exist in three different solid phases with differing densities, depending on temperature.  At room temperature, a phase is observed with a density of 19.07 g/cm3 and a melting point of 1132C. Metallic uranium is a very reactive metal that is silvery in color. (Frequently, a surface oxide layer makes metallic uranium look black.) Uranium powder is pyrophoric. When uranium metal is cut or scratched in the laboratory, a shower of sparks is sometimes observed due to the creation of small particles that ignite. Uranium metal with an oxide coating will burn at 700C to form U3O8. Uranium reacts with hot water to produce UO2 and UH3.In reactors, uranium is alloyed with zirconium to resist corrosion and radiation damage. Metallic uranium can be produced by the reduction of UF4.



Uranium Compounds:


Uraniumexists in the +3, +4, +5, and +6 oxidation states.  The +5 state disproportionate to the +4 and +6 states and is of little importance. Trivalent uranium reduces water and therefore there is no stable aqueous chemistry of U3+ although compounds do exist. The most important uranium compounds are the oxides. UO2 is the compound used in reactor fuel. It is a stable refractory material that is brown-black in color and is nonreactive with H2O.  Uranium hydride, UH3,is a reactive black powder.  It is a powerful reducing agent and is pyrophoric.  A mixture of uranium and zirconium hydrides is used as the fuel.