Bond Length in Resonance Structures
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Bond Length in Resonance Structures
In class today we learned that the C-C bond in C6H6 is 1.39 angstroms long. However, a C-C double bond is 1.33 angstroms while a C-C single bond is 1.54 angstroms. Why is the length of the C-C bond closer towards the C-C double bond instead of simply being the average of the single and double bond?
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Re: Bond Length in Resonance Structures
This is a good question, I was also wondering this. Potentially it is because the distance is not a linear equation, but I don't know exact reasoning
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Re: Bond Length in Resonance Structures
The length of the C-C bond in benzene is closer to the C-C double bond due to hybridization of the atoms. The C-C bond has sp2 hybridization, which means there is one sigma and 2 pi bonds. The overlap of these sp2 orbitals leads to the bond length being somewhere between C-C and C=C bond length. The atoms are most stable at that bond length as well, so the length of 1.39 angstroms would be the bond length. I also think that the delocalized electrons involved in pi bonding across the benzene ring could contribute to the bond length being closer to the double bond length, however, I am not certain. Hope this helps!
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Re: Bond Length in Resonance Structures
To add, we saw that the C-C single bond was a larger value because the single bond is longer and weaker. The double bond between C-C was a smaller value because it is a shorter and stronger bond. Double bonds pull the electrons from the two elements in closer, therefore decreasing the bond length.
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