Abstract
Since many of the applications of the Lewis acid-base concepts to problems in the field of surface chemistry are dependent on the use of the three basic models of Lewis acid-base phenomena introduced in the 1960s (the HSAB principle, the E & C equation, and the DN-AN approach), this overview lecture briefly summarizes and comments on the published literature on these models that has appeared since they were least reviewed in 1980. It also comments on the problem of extending them to the multi-site interactions characteristic of polymers and surfaces and suggests some possible directions for future work in this area.