Fifty years of the VSEPR model

The history and development of the VSEPR model since its inception in 1957 are reviewed. Exceptions to the model are discussed and are shown to have led to improvements in the model and to the development of another model – the LCP model – which supplements the VSEPR model. It is shown how recent developments in the analysis of electron densities have provided both strong evidence for the physical basis of the model, and a further understanding of the model and its exceptions. Attempts to extend the VSEPR model to the transition metals are discussed.