### #21 on Practice Final

Posted:

**Sat Dec 09, 2017 3:44 pm**For those of you who went to the review session last night to go over the questions on the practice final, could you explain #21 to me? We are being asked to find the oxidation state of iron in the heme complex. In order to find it, we must find the formal charges of the nitrogen atoms. He demonstrated that 2 are neutral and the other 2 have a -1 charge.

Could someone please explain to me how he came up with those charges? I can't seem to figure out how he got those formal charges just by looking at the diagram.

Could someone please explain to me how he came up with those charges? I can't seem to figure out how he got those formal charges just by looking at the diagram.