We learned that double bonds are stronger and shorter than single bonds. For example, a C—C single bond has an average bond energy of 347 kJ/mole, whereas a C = C double bond has an average bond energy of 611 kJ/mole. According to valence bond theory, why is a double bond not simply twice as strong as a single bond?

(a) Because according to valence bond theory, a double bond is actually composed of two different kinds of bonds, one s and one π.

(b) Because according to valence bond theory, a double bond is the sharing of two electron pairs.

(c) The C = C double bond is an exception. According to valence bond theory, a double bond is generally twice as strong as a single bond.