Question

What is the oxidation numbers of the underlined elements in the following and how do you rationalise your results?

 Fe₃O₄

Answer 1

On taking the O.N. of O as - 2, the O.N. of Fe is found to be `+2 2/3`. However, O.N. cannot be fractional. 

Here, one of the three Fe atoms exhibits the O.N. of +2 and the other two Fe atoms exhibit the O.N. of +3

+2	+3
FeO,	Fe2O3