Do polyatomic ions with an odd number of electrons obey the octet rule?

1 Answer
Dec 21, 2016

Of course they cannot........

Explanation:

So I can give you a well-worn example.

#NO_2#, #"nitrogen(IV) dioxide"# clearly has an odd electron. Why clearly?

A reasonable Lewis structure would be #O=N^(+)-O^-#; there are 6 electrons around nitrogen and thus it bears a positive charge. Because there are only 6 valence electrons around nitrogen, this centre bears (i) a formal positive charge; and (ii) a single, nitrogen-centred electron.

The lone electron on nitrogen is conceived to couple with another #NO_2# centre to form the #O_2N-NO_2# dimer, where there is again formal charge separation. Can you represent this by means of Lewis structures?