Structural elucidation of chemical bonds
Fractional oxidation value does not mean that the number of electrons shared are in fraction. It is considered only to satisfy the possible structure of compound with existing chemical bonds
Fractional oxidation value
Certain compounds like Fe3O4, C3O2, N3H, etc., exhibits a fractional value of oxidation state. This is due to a state exhibited by the element to satisfy the structural elucidation of chemical bonding The stability of such compounds also need to be examined.
Some more species with fractional oxidation value are: S4O6-2, Mn3O4, Pb3O4, Br3O8 etc.
Calculating the oxidation state
Oxidation state of iron in its oxide: Fe3O4:
Consider the oxidation state of Fe as 'x' and -2 state for oxygen.
Then, Fe3O4 = 3x + 4(-2)
0 = 3x - 8
x = 8/3