The chemisorptive interaction of atoms and molecules at metal substrate sur
faces and their reaction have been studied extensively using various theore
tical methods. The present paper reviews the basic concepts of adsorbate bi
nding, physisorptive, covalent, ionic, and competitive at metal surfaces. T
hese concepts are illustrated by selected examples from theoretical studies
based on cluster model calculations. (C) 1999 Elsevier Science B.V. All ri
ghts reserved.