Abstract:
Modern ideas on the elementary chemical step in condensed media are described in relation to reactions involving the transfer of energy, charge, a proton, and valence. It is emphasised that the rates of the above processes in solids and liquids are as a rule limited by the deficiency of free space and not of energy. Local fluctuations in entropy (the packing of the species), enabling the reactants to come into contact with one another in the correct coordination, assume particular importance because of this. The process is controlled either by the equilibrium density of such fluctuations or by the frequency of their generation, which is limited by molecular mobility. The bibliography includes 81 references.