Question

How many resonance structures can be drawn for ${\mathrm{N}}_2\mathrm{O}$?

Answer 1

Resonance:

1. The delocalization of electrons in a polyatomic ion or molecule is described by resonance structures, which are collections of Lewis structures.
2. A single Lewis structure usually fails to explain the bonding in a molecule/polyatomic ion due to the presence of partial charges and fractional bonds. In such cases, chemical bonding is characterized using resonance structures.
3. Valence electron in ${\mathrm{N}}_2\mathrm{O}$$=$Valence electron of oxygen$+$ valence electron of nitrogen.
4. Electronic configuration of oxygen$=1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^4$ therefore, valence electron of oxygen$=6$
5. Electronic configuration of nitrogen$=1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^3$ therefore, valence electron of nitrogen$=5$
6. Total valence electrons of ${\mathrm{N}}_2\mathrm{O}=5\times 2+6\Rightarrow 16$
7. Now we have to align the single, double, and triple bonds between the three atoms, and then give the atoms the remaining electrons in an octet configuration and calculate the formal charge on the nitrogen atom.
8. Formal charge=$\mathrm{Valence}\mathrm{electron}\mathrm{of}\mathrm{atom}-\frac{\mathrm{bonding}\mathrm{electron}}{2}-\mathrm{Non}\mathrm{bonding}\mathrm{electron}$.
9. Formal charge on terminal nitrogen$=5-\frac{6}{2}-2\Rightarrow 0$
10. Formal charge on central nitrogen$=5-0-\frac{8}{2}\Rightarrow 1$

Therefore, there are three resonating structures present of ${\mathrm{N}}_2\mathrm{O}$