Question

Using suitable examples define gerade and ungerade orbitals. (4)

Answer 1

Orbitals which are left unchanged by the operation of inversion (are symmetric) are labelled with a subscript g, while those which undergo a change in sign (are antisymmetric) are labelled u. The symbols g and u come from the German words "gerade" and "ungerade" meaning "even" and "odd" respectively.