Abstract
Various simple models of bimolecular reactions are discussed which provide a qualitative interpretation of the principal aspects of the elementary act in the redistribution of atoms. The limitations imposed by the law of the conservation of total angular momentum have been elucidated for processes involving the intermediate formation of long-lived complexes. The limiting cases of the mechanisms of dislodgment and stripping have been examined for direct processes. The latter mechanism is interpreted in terms of an optical model. A list of 38 references is included.