Uranium compounds: uranium trioxide

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The uranium in uranium trioxide formally is in the oxidation state 6.

Crystal structure of uranium trioxide

Uranium trioxide

  • Formula as often written: UO3
  • Hill system formula: O3U1
  • CAS registry number: [1344-58-7]
  • Formula weight: 286.027
  • Class: oxide


  • uranium trioxide
  • uranium(VI) oxide
  • uranium oxide

Physical properties

  • Colour: orange-yellow
  • Appearance: crystalline solid
  • Melting point: (decomposes to U3O8)
  • Boiling point:
  • Density: 7300 kg m-3


Coming soon...

Element analysis

Element percentages for the elements in uranium trioxide
Element %
O 16.78
U 83.22


Not available

Solid state structure

  • Geometry of uranium:
  • Prototypical structure:

Crystal structure of uranium trioxide

Isotope pattern

What follows is the calculated isotope pattern for the UO3 unit with the most intense ion set to 100%.

Formula: U1O3

mass  %
282   0.0 
283 0.7
284 0.0
285 0.0
286 100.0 __________________________________________________
287 0.1
288 0.6


The data on these compounds pages are assembled and adapted from the primary literature and several other sources including the following.

  • R.T. Sanderson in Chemical Periodicity, Reinhold, New York, USA, 1960.
  • N.N. Greenwood and A. Earnshaw in Chemistry of the Elements, 2nd edition, Butterworth, UK, 1997.
  • F.A. Cotton, G. Wilkinson, C.A. Murillo, and M. Bochmann, in Advanced Inorganic Chemistry, John Wiley & Sons, 1999.
  • A.F. Trotman-Dickenson, (ed.) in Comprehensive Inorganic Chemistry, Pergamon, Oxford, UK, 1973.
  • R.W.G. Wyckoff, in Crystal Structures, volume 1, Interscience, John Wiley & Sons, 1963.
  • A.R.West in Basic solid state chemistry Chemistry, John Wiley & Sons, 1999.
  • A.F. Wells in Structural inorganic chemistry, 4th edition, Oxford, UK, 1975.
  • J.D.H. Donnay, (ed.) in Crystal data determinative tables, ACA monograph number 5, American Crystallographic Association, USA, 1963.
  • D.R. Lide, (ed.) in Chemical Rubber Company handbook of chemistry and physics, CRC Press, Boca Raton, Florida, USA, 77th edition, 1996.
  • J.W. Mellor in A comprehensive treatise on inorganic and theoretical chemistry, volumes 1-16, Longmans, London, UK, 1922-1937.
  • J.E. Macintyre (ed.) in Dictionary of inorganic compounds, volumes 1-3, Chapman & Hall, London, UK, 1992.

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