Final answer:
A carbon-carbon double bond is stronger and shorter than a single bond due to higher bond energy, with the additional pi bond contributing to this increased strength and reduced length.
Step-by-step explanation:
A carbon-carbon double bond has a greater bond energy than a carbon-carbon single bond, meaning that the double bond is stronger and shorter than the single bond. This is because, as the number of electron pairs in a bond increases—going from a single to a double bond—the strength of the bond between the two carbon atoms increases, leading to a decrease in bond length. This relationship is consistent with trends shown in scientific data where an average carbon-carbon single bond has a bond energy of 347 kJ/mol, whereas a carbon-carbon double bond has an added bond energy of 267 kJ/mol due to the presence of the è pi bond in addition to the sigma bond, which already exists in the single bond.