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Thursday, March 7, 2013


A nuclear chain reaction
A neutron collides with a U-235 atom. U-236 forms briefly before it undergoes nuclear fission; this yields new atoms plus energy plus more neutrons. These newly released neutrons can cause more U-235 to split. If U-235 atoms are present in high enough concentrations, a nuclear chain reaction results. Image by Fastfission

Data Zone

Classification: Uranium is an actinide metal
Color: silvery-white
Atomic weight: 238.0289, no stable isotopes
State: solid
Melting point: 1135 oC, 1408 K
Boiling point: 4130 oC, 4403 K
Electrons: 92
Protons: 92
Neutrons in most abundant isotope: 146
Electron shells: 2,8,18,32,21,9,2
Electron configuration: [Rn] 5f3 6d1 7s2
Density @ 20oC: 18.9 g/cm3

Atomic volume: 12.59 cm3/mol
Structure: orthorhombic
Hardness: 6.0 mohs
Specific heat capacity 0.12 J g-1 K-1
Heat of fusion 8.520 kJ mol-1
Heat of atomization 482 kJ mol-1
Heat of vaporization 422.58 kJ mol-1
1st ionization energy 597.6 kJ mol-1
2nd ionization energy 1420 kJ mol-1
3rd ionization energy
Electron affinity
Minimum oxidation number 0
Min. common oxidation no. 0
Maximum oxidation number 6
Max. common oxidation no. 6
Electronegativity (Pauling Scale)
Polarizability volume 27.4 Å3
Reaction with air mild, ⇒ U3O8
Reaction with 15 M HNO3 passivated
Reaction with 6 M HCl mild, ⇒ H2
Reaction with 6 M NaOH none
Oxide(s) UO, UO2, UO3 , U2O5, U3O8
Hydride(s) UH3
Chloride(s) UCl, UCl3, UCl4, UCl5, UCl6
Atomic radius 175 pm
Ionic radius (1+ ion)
Ionic radius (2+ ion)
Ionic radius (3+ ion) 116.5 pm
Ionic radius (1- ion)
Ionic radius (2- ion)
Ionic radius (3- ion)
Thermal conductivity 27.5 W m-1 K-1
Electrical conductivity 3.6 x 10-6 S m-1
Freezing/Melting point: 1135 oC, 1408 K

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