Stereoisomerism

These are molecules with the same structural formula but their atoms have different positions in space.

e.g. the CH₃ groups in CH₃CH=CHCH₃ can be placed on the same side of the double bond in one stereoisomer and on opposite sides in another.

See also: Diastereomers, Enantiomers, Isometry, Racemic Mixture, Stereochemistry, Structural Isomerism.