Question

why o=n=o is not one of them

and can you explain this answer for me?

8.70 Resonance must be present any time that a single Lewis structure is inadequate in explaining one or more aspects of a molecule or ion. The two N-O bonds in NO2 are equivalent in bond length and bond energy; no single Lewis structure can account for this. The following Lewis structures may be drawn for NO2: 6=–vò=N- v o -N=0 : < = The average of all of these structures gives equivalent N-O bonds with a bond length that is between N-O and N=0.

Answer 1

Answer :

O=N=O is not the resonance form of NO_{​​​​​2} this is because N has 5 electron in its outermost shell . Nitrogen generally form 3 bonds by using its 3 2p electrons. For making 4th bond , it has to use its lone pair of electrons to make coordinate bond with oxygen which is not possible because oxygen does not have vacant orbital to take lone pair of electrons of nitrogen . So, O=N=O does not form .

Resonance hybrid of NO_{​​​​​2} contain 3 bond overall . There is partial double bond character in each N and O bond .