A simple bond-order-conservation method that predicts stability of adatom structures on metal surfaces is presented. This theory introduces the concepts of the n-center 2-electron bond and metal valence. Metal valence is denned in terms of the effective atomic number (EAN) as given by valence bond theory. Adatom coverage that satisfies the unsaturated metal valence at the surface is shown to agree with experimental observations of adlayer coverages. Surface reconstructions and alloy surface composition are in good agreement with the model predictions. The energetics of reaction on metal surfaces, such as barriers for molecular dissociation are determined. Both metal valence and surface structure alter the ability of a metal surface to dissociate molecules. The optimal catalytic activity for formic acid decomposition occurs with the late Group VIII metals. This relatively simple theory gives excellent predictions of adlayer structures and reaction energetics on Group VI, VII, VIII and IB metals.
All Science Journal Classification (ASJC) codes