Ferric, Fe3+, and ferrous, Fe2+ species are common........For any formula, it useful to be able to quickly assign the oxidation state........
1. The oxidation number of a free element is always 0.
2. The oxidation number of a mono-atomic ion is equal to the charge of the ion.
3. For a given bond, X-Y, the bond is split to give X+ and Y−, where Y is more electronegative than X.
4. The oxidation number of H is +1, but it is -1 in when combined with less electronegative elements.
5. The oxidation number of O in its compounds is usually -2, but it is -1 in peroxides.
6. The oxidation number of a Group 1 element in a compound is +1.
7. The oxidation number of a Group 2 element in a compound is +2.
8. The oxidation number of a Group 17 element in a binary compound is -1.
9. The sum of the oxidation numbers of all of the atoms in a neutral compound is 0.
10. The sum of the oxidation numbers in a polyatomic ion is equal to the charge of the ion.
And so for iron complexes and salts such as Fe2(CO)9, FeCl3, Fe(NO3)2, can you suggest an oxidation state?
