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Uranium U (Element 92) of Periodic Table

Uranium U (Element 92) of Periodic Table

92 U Uranium

Appearance:  Silvery gray metallic

Mass number:  238

Atomic weight:  238.02891 g/mol

Atomic number (Z):  92

Electrons:  92

Protons:  92

Neutrons:  146

Period:  7

Block:  f

Element category:  Actinide

Electrons per shell:  K2, L8, M18, N32, O21, P9, Q2

Electron configuration:  1s22s22p63s23p63d104s24p64d105s25p64f145d106s26p65f36d1 7s2

Phase:  Solid

Melting point:  1405.3 K (1132.2 oC)

Boiling point:  4404 K (4131 oC)

Density:  19.1 g/cm3 (solid), 17.3 g/cm3 (Liquid at m.p)

Half Life(s):  1.41E+17

Lifetime(s):  2.03E+17

Decay mode: α decay

Neutron cross section (Barns):  7.57

Heat of fusion:  9.14 kJ/mol

Heat of vaporization:  417.1 kJ/mol

Molar hear capacity:  27.665 J/(mol∙K)

Thermal expansion:  0.0000139 K-1

Oxidation states:  6, 5, 4, 3, 2, 1

Ion charge:  U6+, U4+

Electronegativity:  Pauling scale: 1.38

Valence:  (+2), +3, +4, (+5), +6

Ionization energies: 1st: 597.6 kJ/mol 2nd: 1420 kJ/mol

Atomic radius:  156 pm

Covalent radius: 196

Vander Waals radius:  186 pm

Crystal structure:  Orthorhombic

Grid parameters:  a=2.854 Å, b=5.870 Å, c=4.955 Å

Speed of sound thin rod: 3155 m/s

Thermal expansion: 13.9 μm/(m∙K)

Thermal conductivity:  27.5 W/(m∙K)

Electrical conductivity:  36×105

Electrical resistivity:  0.280 μΩ∙m

Super conducting point:  0.69 k (-272.46 oC)

Magnetic ordering:  Paramagnetic

Volume magnetic susceptibility:  0.0004096

Mass magnetic susceptibility:  0.0000000215 m3/kg

Molar magnetic susceptibility:  0.000000005118

Young’s modulus:  208 GPa

Shear modulus:  111 GPa

Bulk modulus:  100 GPa

Poisson ratio:  0.23

Mohr hardness:  6

Vickers hardness:  1960 – 2500 MPa

Brinell hardness:  2350 – 3850 MPa

Molar volume:  0.000012495 m3/mol

CAS Number:  7440-61-1

Naming:  After planet Uranus

Discovery:  Martin Heinrich Klaproth (1789)

First isolation:  Eugène-Melchior Péligot (1841)

Isotopes:  232U 233U 234U 235U 236U 238U

Uses:  It is Used as Nuclear fuel to generate electricity in Nuclear power stations. Other synthetic  transuranium elements are made with the help of Uranium. It is also used by the military to power nuclear submarines and in nuclear weapons.

Naturally occurring uranium is consists of 99% uranium-238 and 1% uranium-235. Uranium-235 is the only naturally occurring fissionable fuel (a fuel that can sustain a chain reaction). Uranium fuel used in nuclear reactors is enriched with uranium-235. The chain reaction is carefully controlled using neutron-absorbing materials.

The heat generated by the fuel is used to create steam to turn turbines and generate electrical power.

In a breeder reactor uranium-238 captures neutrons and undergoes negative beta decay to become plutonium-239. This synthetic, fissionable element can also sustain a chain reaction.

Depleted uranium is uranium that has much less uranium-235 than natural uranium. It is considerably less radioactive than natural uranium. It is a dense metal that can be used as ballast for ships and counterweights for aircraft and It is also used in ammunition and armour.

Biological role:  Uranium  is a toxic metal due to Radioactivity

Natural abundance:  Uranium occurs naturally in several minerals such as uranite (pitchblende), brannerite and carnotite. It is also found in phosphate rock and monazite sands. World production of uranium is about 41,000 tonnes per year.

Abundance of Uranium  2×10-8%(In Universe), 1×10-7%(In Sun), 9.8×10-7(In Meteorites), 0.00018%(In Earth’s Crust), 3.3×10-7%(In Oceans), 1×10-7%(In Humans)

Extracted uranium is converted to the purified oxide, known as yellow-cake. Uranium metal can be prepared by reducing uranium halides with Group 1 or Group 2 metals, or by reducingsuranium oxides with calcium or aluminium.

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