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The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 15 (2010) pp 340-343

Prediction of Bond Angles of Hydrides from Electronegativities: Reconciling VSEPR and VB

Louis J. Kirschenbaum and Benjamin P Ruekberg*

Chemistry Department, University of Rhode Island, 51 Lower College Road, Kingston, RI 02881,
Received September 2, 2009. Accepted April 9, 2009.

Published: 17 September 2010

Abstract. VSEPR, Valence Shell Electron Pair Repulsion, and Valence Bond hybridization predict/describe bond angles for systems consisting of a central atom surrounded by covalently bound ligands. For a central atom with identical ligands and lone pairs, VSEPR rationalizes the decrease of observed bond angles from the ideal bond angles based on the greater repulsion of lone pairs, acknowledging an influence of electronegativity in the greater effect of this lone pair repulsion in reducing the bond angles for ligands of greater electronegativity. In this paper, we formulate a quantitative method, which, for the Group Va and Group VIa hydrides, successfully correlates bond angles with a simple function of the electronegativities of the partner atoms. Appendices: (1) s-character, acidity and methyl radical geometry, (2) Electronegativities calculated from bond angles, (3) Calculation of s-character from out-of-plane angle of the methyl radical.

Key Words: In the Classroom; general chemistry; molecular properties & structure; VSEPR theory; valence bond theory; covalent bonding; bond angles; orbital hybridization

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