Valence-shell electron pair repulsion, and

VSEPR stands for Valence Shell Electron Pair Repulsion and these electron pair repulsions are responsible for the shapes of molecules and polyatomic ions, such as NH+. 

M. B. Hall,/. Am. Chem. Soc., 100,6332 (1978). Valence Shell Electron Pair Repulsions and the Pauli Exclusion Principle. 

VALENCE-SHELL ELECTRON-PAIR REPULSIONS AND MOLECULAR GEOMETRY... 

Valence-bond theory, 32—34, 42, 46 Valence electrons, 10 and Lewis structures, 20 Valence-shell electron pair repulsion and molecular geometry, 26-29, 45 L-Valine, 1054, 1059... 

Skill 21.2 Apply the concepts of Lewis structures, valence-shell electron-pair repulsion, and hybridization to describe molecular geometry and bonding. 

While valence shell electron pair repulsion and steric repulsion between ligands may act in a synergetic manner on the acceptor molecule, they are expected to be opposed on the donor molecule the VSEPR model predicts that partial removal of a lone pair on the donor atom should lead to a reduction of D-C bond distances and an increase of the CDC valence angles. Steric repulsion between the methyl groups bonded to D and the entire acceptor... 

The rules are known in chemistry as the VSEPR rules, where VSEPR is the acronym of valence-shell electron-pair repulsion, and they were devised in 1957 by Gillespie and Nyholm, ] two young scientists—one English, Gillespie, and the other Australian, Nyholm—who were both students of Sir Christopher Ingold, one of the greatest British chemists in the post-Second World War era. 

Hall MB (1978) Valence shell electron pair repulsions and the Pauli exclusion principle. J Am Chem Soc 100 6333-6338. doi 10.1021/ja00488a007... 

In this section the geometrical parameters deteimined for the sulphur bond configurations in the sulphone molecules are compared, characteristic tendencies in their changes are pointed out, and explanations are sought employing considerations on valence shell electron pair repulsions and on non-bonded (atom-atom) interactions. The role of electron pair repulsions is examined for the changes... 

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