The goal of this study was to examine general chemistry students’ understanding of the relationship between the structure of chemical compounds and the chemical/physical properties of these compounds. Case studies of three undergraduate engineering students enrolled in the second semester of a year-long general chemistry course were conducted using Lewis electron-dot structures as a model for chemical structure. Over the course of a series of five interviews, each student was asked to use Lewis dot structures as a basis for analyzing five problem sets corresponding to the following topics from the second-semester course: Lewis acid–base reactions, the solubility of gases in aqueous solution, acid-dissociation equilibria, chemical kinetics, and thermodynamics. The interview data suggested that the students’ perceptions or representations of Lewis dot structures could be classified primarily as either verbal-linguistic or symbolic. The two students for whom these structures were most often verbal-linguistic representations exhibited a dependence on the external or visual features of dot structures. Their descriptions of the aforementioned chemical and physical phenomena tended to be static and inconsistent with scientific reality. The student for whom these structures were more likely to be symbolic representations exhibited more dynamic and interactive descriptions, which were more consistent with what one would expect from a practicing chemist. For this student, the dot structures were true symbols in the sense that they had meaning beyond their external, visual features.
Shane et al. (Fri,) studied this question.