Actinium(III) oxide
Actinium sesquioxide.jpg
Unit cell, ball and stick model of actinium(III) oxide
IUPAC name
Actinium(III) oxide
Systematic IUPAC name
Actinium(3+) oxide
Other names
Actinium sesquioxide
3D model (JSmol)
ECHA InfoCard 100.031.275 Edit this at Wikidata
EC Number
  • 234-417-6
  • InChI=1S/2Ac.3O/q;;3*-2 checkY[pubchem]
  • [O--].[O--].[O--].[Ac+3].[Ac+3]
Molar mass 502.053 g/mol
Appearance white
Melting point 2,327 °C (4,221 °F; 2,600 K)[1]
Trigonal, hP5
P3m1, No. 164
a = 408 pm, c = 630 pm[1]
Related compounds
Other cations
Lanthanum(III) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Actinium(III) oxide is a chemical compound containing the rare radioactive element actinium. It has the formula Ac2O3. It is similar to its corresponding lanthanum compound, lanthanum(III) oxide, and contains actinium in the oxidation state +3.[2][3] Actinium oxide is not to be confused with Ac2O (acetic anhydride), where Ac is an abbreviation for acetyl instead of the symbol of the element actinium.



  1. ^ a b Christine Guéneau; Alain Chartier; Paul Fossati; Laurent Van Brutzel; Philippe Martin (2020). "Thermodynamic and Thermophysical Properties of the Actinide Oxides". Comprehensive Nuclear Materials 2nd Ed. 7: 111–154. doi:10.1016/B978-0-12-803581-8.11786-2.
  2. ^ Actinium, Great Soviet Encyclopedia (in Russian)
  3. ^ Sherman, Fried; Hagemann, French; Zachariasen, W. H. (1950). "The Preparation and Identification of Some Pure Actinium Compounds". Journal of the American Chemical Society. 72 (2): 771–775. doi:10.1021/ja01158a034.