The element uranium is named after the planet Uranus. uranium was the first known radioactive element. In the early 20th century, some manufacturers used uranium in the glass of crystal bowls, only to realize later that it was a harmful metal. An unstable form, the radioactive isotope, 235U, is used as fuel in nuclear reactors and atomic bombs.

Summary of properties (U)

Atomic weight238.02891(3)
Discoverer (year)Klaproth, Martin Heinrich (1789)
Natural formmetallic solid (orthorombic)
Electron configuration[Rn] 53 6d1 7s2
Melting point (ºC)1132
Boiling point (ºC)3818
Abundance in earth's crust (ppm)2.7
Isotope (abundance)234U (0.0054), 235U (0.7204), 238U (99.2742)
Density g/cm319
Van der Waals radius (pm)241
Covalent radius (pm)183
Electronegativity (Pauling)1.38
Vaporization enthalpy (kJ/mol)423.00
Enthalpy of fusion (kJ/mol)9.14
Specific heat capacity (J/g·K) at 25ºC and 1 atm0.12
Thermal conductivity (W/cm·K) at 25ºC and 1 atm0.280
Oxidation state+6, +5, +4, +3
Electron affinity (eV)
1st Ionization potential (eV)6.1939

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