According to the formula it should be +5 but according to its structure shouldn't it be +4? How is it +5 then?
2$\begingroup$ $5\cdot(-2) + 2\cdot(+5) = 0$ $\endgroup$– Klaus-Dieter WarzechaFeb 18, 2016 at 7:44
$\begingroup$ But according to the structure it should be + 4 $\endgroup$– rishabh guptaFeb 18, 2016 at 8:32
1$\begingroup$ No. Why do you think so? $\endgroup$– aventurinJul 2, 2016 at 17:46
1$\begingroup$ A coordinate bond gives a formal charge of +1 to N, implying that it effectively gets a raise in oxidation state by +2 $\endgroup$– SubZeroMar 25, 2017 at 17:59
It is +5 .Even by the structure.
Notice that it is a resonance structure of:
Now one of the bonds are coordinate bonds where nitrogen donates BOTH its electrons to oxygen (otherwise, oxygen cannot have a single bond without a negative charge and no peroxy type linkage).
So, while determining oxidation state from the structure :
1$\begingroup$ Your second image is better since it shows formal charges. $\endgroup$– JanJul 2, 2016 at 18:10
$\begingroup$ True, but that's not much of an improvement. Evidently, I picked it up for representation purpose. $\endgroup$– VarunJul 4, 2016 at 2:37
4$\begingroup$ Oh, I always advocate properly assigning formal charges to all atoms that need them, which is why I wouldn’t have upvoted your answer if only the first structure were shown ;) $\endgroup$– JanJul 5, 2016 at 0:11