Geometrical (cis–trans) isomers have the same molecular formula and the same structure (sequence of bonded atoms), but differ in the spatial arrangement of groups around a double bond or ring, which cannot rotate freely. Example: cis-but-2-ene and trans-but-2-ene, which have the two methyl groups on the same side and on opposite sides of the C=C bond. Differences in the position of a functional group or the length of the chain give structural isomers. So geometrical isomers differ in the spatial arrangement of atoms.
ConceptCis-trans isomers
Organic Chemistry - Some Basic Principles and Techniques in past papers
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