A carbon–carbon single bond consists of how many sigma and pi bonds?

A carbon–carbon single bond consists of how many sigma and pi bonds?

• A. 1 sigma, 0 pi
• B. 2 sigma, 0 pi
• C. 1 sigma, 1 pi
• D. 0 sigma, 1 pi

Answer: (A)

A carbon–carbon single bond is formed by end-to-end overlap of orbitals along the line between the two nuclei, creating one sigma bond. There is no second region of electron density above and below the bond axis, so no pi bond is present. Thus, a single C–C bond has one sigma bond and zero pi bonds. If there were a second bond, as in a double bond, that additional bond would be a pi bond; in a triple bond there would be two pi bonds in addition to the one sigma.

A carbon–carbon single bond is formed by end-to-end overlap of orbitals along the line between the two nuclei, creating one sigma bond. There is no second region of electron density above and below the bond axis, so no pi bond is present. Thus, a single C–C bond has one sigma bond and zero pi bonds. If there were a second bond, as in a double bond, that additional bond would be a pi bond; in a triple bond there would be two pi bonds in addition to the one sigma.