If the the chlorine atoms are next to or adjacent each other, the isomer is called " cis". If one carbon of the double bond has two identical groups such as 2 H's or 2 Cl's or 2 CH3 etc. there cannot be any geometric isomers.
What is cis isomer example?
Cis and trans isomers are possible only if an alkene has two different atoms or groups of atoms attached to each double-bonded carbon atom. For example, in 1,2-dichloroethene, each unsaturated carbon atom has a chlorine atom and a hydrogen atom attached to it.
What makes a cis isomer?
Cis–trans isomerism, also known as geometric isomerism or configurational isomerism, is a term used in organic chemistry. ... In the context of chemistry, cis indicates that the functional groups (substituents) are on the same side of some plane, while trans conveys that they are on opposing sides.
