Molecular structure : from Lewis dot structure to molecular geometry : an honors thesis (HONRS 499)

Abstract

This report is of the results of a study designed to answer two questions. The first question is to understand why students have difficulty constructing three-dimensional molecular models from the two-dimensional Lewis structures. The second question is to identify ways in which instruction could be changed to improve the student's ability to carry out this task. Analysis of first semester general chemistry student interviews yielded the following findings. First, all the general chemistry students memorized the molecular geometry that corresponded to a specific Lewis structure. The students had little understanding of the origin of molecular geometries, the importance of shape, and the role of lone pairs of electrons. Second, having the students build representations of molecules helped them construct a more sophisticated understanding of molecules and chemical phenomena. These findings provide a basis for improved teaching methods and an understanding of student's misconceptions.