Pi Bond Sideways overlap of parallel p orbitals No rotation is possible without breaking the pi bond 63 kcal/mole) Cis isomer cannot become trans without a chemical reaction occurring CH H H H . CH HoC CH3 H CH3 H3C=C CIS no overlap with the ends perpendicular trans Chapter 7Chapter 7 5 Pi Bond • Sideways overlap of parallel p orbitals. • No rotation is possible without breaking the pi bond (63 kcal/mole). • Cis isomer cannot become trans without a chemical reaction occurring. =>