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The valence-shell electron-pair repulsion model (VSEPR model) provides a simple way of predicting the molecular geometries. However, the particularly challenging part in demonstrating the VSEPR models is to show the “best” arrangement of bonding and nonbonding electrons around the central atom that minimizes the repulsion among the electron pairs. Rigid molecular models do not facilitate quick and easy interchangeable geometries. In this article, the authors present a versatile use of magnets (as electron domains) and a ball bearing (as a central atom).
A selection from Journal of College Science Teaching—November/December 2010
While this demonstration is meant for college students, I use this exercise in my chemistry classes as a hands-on actvity to model VESPR. For many students, VESPR is a mind-boggling concept. This demonstration provides a concrete way to show the various arrangements. The arrangements can be manipulated easily to show all possibilities.
Ruth Hutson (Westmoreland, KS)
The authors have described a creative approach to creating visual models of the molecular shapes predicted by VSEPR theory. The coverage is not comprehensive. This demonstration should be accompanied by lecture content that discusses the greater repulsions between two non bonding electron pairs and how this influences the geometries of molecules having 5 electron domains where 2 or 3 of those electron domains are non-bonding. These two cases are the most conceptually difficult for students.
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