Abstract
The present state of the theory of the equilibrium isotope effects of hydrogen has been examined using a new approach developed by the present authors, namely the coordinate analysis of isotope effects. The mathematics of the theory have been described briefly. The conditions under which the isotopic effect is localised have been formulated. The relationship of the isotope effects in protium–deuterium and protium–tritium replacements has been refined. Particular attention has been made to clear methods for interpreting the parameter ln β, making it possible to reveal the relationship between the isotope effect and intramolecular properties, and to systematise isotope effects on the basis of concepts having a clear physical significance. The isotope effects for the principal classes of hydrogen compound have been analysed and systematised. The factors determining the magnitude and nature of the variation in the equilibrium isotope effect have been established. The bibliography includes 66 references.