An Inquiry-Based Molecular Modeling Laboratory for Students to Discover VSEPR Theory and Resonance Structures

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 24 (2019) pp 59-61

An Inquiry-Based Molecular Modeling Laboratory for Students to Discover VSEPR Theory and Resonance Structures

Anna Le, Gregory James Marquino, and Yingbin Ge*

Department of Chemistry, Central Washington University, Ellensburg, Washington 98926, yingbin@cwu.edu
Received February 5, 2019. Accepted March 13, 2019.

Published: 3 April 2019

Abstract. An inquiry-based molecular modeling laboratory was designed to help first-year general chemistry students discover valence shell electron pair repulsion (VSEPR) theory and resonance structures. In this laboratory, students use GaussView and Gaussian 09W to carry out optimization calculations of various structures with different symmetries for the same molecule. Students then compare the optimized energies and explain the results based on the Lewis structures they drew as part of the pre-lab assignment. Students also determine the resonance structures of benzene by comparing the bond distances of the six C-C bonds in benzene with the C-C bond distances in ethane and ethene. An optional exercise regarding the ozone structure further challenges students to deepen their understanding of VSEPR theory and resonance structures. This laboratory has challenged more than a thousand students in the past four years at Central Washington University. These students learned more and far better than those who did the traditional instruction-based molecular modeling laboratory.

Key Words: Laboratories and Demonstrations; general chemistry; inquiry-based learning; VSEPR theory; resonance structures; molecular geometry; electron geom

(*) Corresponding author. (E-mail: yingbin@cwu.edu)

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Supporting Materials:

The lab manual, which includes the report sheets and the pre- and post-lab assignments, is provided in the Supporting Materials. The keys to the pre- and post-lab assignments are provided as well. Readers are welcomed and encouraged to use this lab manual freely, without or with modifications, for non-commercial purposes. (963 KB)