Cis/Trans Isomerism

***Cis/trans* isomerism (geometric isomerism)** is a type of **stereoisomerism**, which describes the relative orientation of ligands in space. This type of isomerism is encountered e.g. in alkanes containing in their structure a double bond that does not allow free rotation. If there is on any carbon atoms of the double bond two different ligands, the said compound exists in two distinct spatial forms – *cis* and *trans* isomer. ***Cis*-isomers** have the same ligands placed in the same half plane with respect to the double bond, whereas ***trans*-isomers** have the same ligands placed in opposite side with respect to the plane of the double bond.