Iron compounds: iron oxide

iron symbol icon

The iron in iron oxide formally is in the oxidation state 2.

Crystal structure of iron oxide

Iron oxide

  • Formula as often written: FeO
  • Hill system formula: Fe1O1
  • CAS registry number: [1345-25-1]
  • Formula weight: 71.844
  • Class: oxide


  • iron oxide
  • iron(II) oxide

Physical properties

  • Colour: black
  • Appearance: crystalline solid
  • Melting point: 1370°C
  • Boiling point: decomposes at 3414
  • Density: 6000 kg m-3


Coming soon...

Element analysis

Element percentages for the elements in iron oxide
Element %
Fe 77.73
O 22.27


Not available

Solid state structure

  • Geometry of iron:
  • Prototypical structure: NaCl (rock salt)

Crystal structure of iron oxide

Isotope pattern

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

Formula: Fe1O1

mass  %
70   6.3 ___
71 0.0
72 100.0 __________________________________________________
73 2.4 _
74 0.5
75 0.0


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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iron atomic number