Definitions: Geometric Isomers
Additionally, consider the next two molecules.
In the molecule on the left, the methyl groups are on the same side of the double bond (cis
), and in the molecule on the right, the methyl groups are on opposite sides of the double bond (trans
). A double bond can be thought of like a two-membered "ring," shown below. This two-membered "ring" locks groups into positions like the six-membered rings shown in the first set of examples. Therefore, these are geometric isomers
because the double bond will not allow these molecules to interconvert.