Cis,Trans Isomers Require That End Groups Must Differ in Pairs Cis-trans isomerism is not limited to disubstituted alkenes. It can occur whenever both double-bond carbons are attached to two different groups. If one of the double-bond carbons is attached to two identical groups,then cis-trans isomerism is not possible These two compounds are identical; they are not cis-trans isomers. These two compounds are not identical; they are cis-trans isomers. B 2004 Thomson/Brooks Cole Cis, Trans Isomers Require That End Groups Must Differ in Pairs Cis-trans isomerism is not limited to disubstituted alkenes. It can occur whenever both double-bond carbons are attached to two different groups. If one of the double-bond carbons is attached to two identical groups, then cis-trans isomerism is not possible