Uranium Oxide

Uranium Oxide



 uranium (V, VI) oxide

  • Formula as commonly written: U3O8
  • Hill system formula: O8U3
  • CAS registry number: [1344-59-8]
  • Formula weight: 842.082
  • Class: oxide


  • uranium (V, VI) oxide
  • uranium oxide
  • pitchblende
  • triuranium octaoxide

Physical properties

  • Colour: very dark green-black
  • Appearance:
  • Melting point: 1150°C; 1300°C (decomposes to UO2)
  • Boiling point:
  • Density: 8380 kg m-3



Element analysis and oxidation numbers

For each compound, and where possible, a formal oxidation number for each element is given, but the usefulness of this number is limited, especially so for p-block elements in particular. Based upon that oxidation number, an electronic configuration is also given but note that for more exotic compounds you should view this as a guide only.

Element % Formal oxidation state Formal electronic configuration
O 15.20 -2 [He].2s2.2p6
U 84.80


Not available

Solid state structure

  • Geometry of uranium: 7 coordinate: pentagonal bipyramidal
  • Prototypical structure:


Isotope pattern

What follows is the calculated isotope pattern for the U3O8 unit with the most intense ion set to 100%.

Formula: U3O8

mass  %836   0.0 837   0.0 838   0.0 839   2.2 _ 840   0.0 841   0.0 842 100.0 843   0.3 844   1.6 845   0.0 846   0.0



CAS # Formula Formula Weight
U3O8 842.09
Color Crystalline Form Specific Gravity Melting Point Boiling Point
olive-grn-blk 8.30 d 1300 to UO2
Solubility in 100 parts
Cold Water Hot Water Other Reagents
s HNO3

International Bio-Analytical Industries, Inc. is the worlds leading manufacturer of specialty Uranium compounds and has now entered into full production of Uranyl Acetate, Uranyl Nitrate, Uranium Tetra Fluoride, Uranium Oxide and other fine specialty uranium compounds and reagents manufactured exclusively from depleted uranium.

At this time Uranyl Acetate, Uranyl Nitrate and Uranium Tetra Fluoride are available in kilogram and smaller quantities to companies and institutions both nationally and internationally where the sale is permitted by law.

Should you require further information and pricing regarding Uranyl Acetate, Uranyl Nitrate, Uranium Tetra Fluoride or other fine specialty chemical compounds formulated from depleted uranium then please contact our manufacturing department by submitting the following form, or if you wish call or fax the following numbers with your request.  Fax (561) 892-8450

Uranium Oxide
Ingredient Name:        Uranium Oxide: U3O8CAS Number:              11344-57-6Percent:                       ca 100Exposure Limits:         * OSHA PEL: 0.05 mg/m3, 8‑hr TWA

Appearance & Odor:  Uranium oxide is usually a dull, dark charcoal-gray or flat black colored                     powder (U308) with no detectable odor.

Boiling point:  NA                                                                    Specific Gravity (H2O=l):       8.30

Vapor Density (Air=1):  NA                                                       Vapor Pressure:                        NA

Water Solubility (%):  Insoluble                                                Melting Point:        >>1300 °C

Evaporation Rate:  NA                                                              % Volatile By Volume:        NA

Molecular Weight:  842.09

Melting point for oxides is much higher than for metal (1132 °C),

U3O8 decomposes to UO2 at 1300°C.

{UO2 specific gravity = 10.96, melting point = 2878 °C.}

{UO3 specific gravity =  7.29  (melting point NA)}

Meets ACS specifications





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