VSEPR theory

Model for predicting molecular geometry

Valence shell electron pair repulsion (VSEPR) theory ( VESP-ər, və-SEP-ər) is a model used in chemistry to predict the geometry of individual molecules from the number of electron pairs surrounding their central atoms. It is also named the Gillespie-Nyholm theory after its two main developers, Ronald Gillespie and Ronald Nyholm but it is also called the Sidgwick-Powell theory after earlier work by Nevil Sidgwick and Herbert Marcus Powell. The premise of VSEPR is that the valence electron pairs surrounding an atom tend to repel each other.

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