Answer
See the explanation
Work Step by Step
To rationalize the observations regarding the bond lengths in nitrous oxide (N2O), we need to consider the resonance structures and their corresponding formal charges.
The three possible Lewis structures for N2O are:
1. N-N-O' (linear structure)
2. N=N-O: (bent structure)
3. :N-N=O: (bent structure)
Given the bond lengths provided:
- N-N: 167 pm
- N=O: 115 pm
- N=N: 120 pm
- N-O: 147 pm
- N≡N: 110 pm
Rationalization of the observed bond lengths:
1. N-N bond length in N2O is 112 pm:
The observed N-N bond length of 112 pm is shorter than the typical N-N single bond length of 167 pm. This suggests that the N-N bond has some double bond character, which is consistent with the resonance structure N=N-O:.
2. N-O bond length in N2O is 119 pm:
The observed N-O bond length of 119 pm is shorter than the typical N-O single bond length of 147 pm. This indicates that the N-O bond has some double bond character, which is consistent with the resonance structure :N-N=O:.
Formal charges:
1. N-N-O' (linear structure):
- Formal charges: N (0), N (+1), O (-1)
2. N=N-O: (bent structure):
- Formal charges: N (0), N (0), O (0)
3. :N-N=O: (bent structure):
- Formal charges: N (-1), N (+1), O (0)
Elimination of resonance structures based on formal charges:
The resonance structure with the lowest formal charges is the most stable and preferred. In this case, the resonance structure with the formal charges N (0), N (0), O (0) is the most stable and consistent with the observed bond lengths.
The other two resonance structures, N (0), N (+1), O (-1) and N (-1), N (+1), O (0), have higher formal charges and are less stable. Therefore, they can be eliminated as the dominant contributors to the overall structure of N2O.
This is consistent with the observed bond lengths, as the resonance structure with the lowest formal charges, N=N-O:, best explains the shorter N-N and N-O bond lengths observed in nitrous oxide.
