Technical term for ‘handedness’ (from cheiro, Greek for hand). Objects that lack rotational symmetry but possess bilateral (reflective) symmetry have a left side and a right side (as we do). Objects with rotational symmetry but without reflective symmetry (e.g. a pinwheel or a Möbius strip) have mirror image forms (sinistral or dextral) that are non-super imposable (enantiomers). Solutions of enantiomeric molecules rotate the plane of a polarized light beam in opposite directions by the same amount (‘optical activity’).
