Student Understanding of Intermolecular Forces: A Multimodal Study

The ability to use representations of molecular structure to predict the macroscopic properties of a substance is central to the development of a robust understanding of chemistry. Intermolecular forces (IMFs) play an important role in this process because they provide a mechanism for how and why molecules interact. In this study, we investigate student thinking about IMFs (that is, hydrogen bonding, dipole–dipole interactions, and London dispersion forces) by asking general chemistry college students to both describe their understanding in writing and to draw representations of IMFs. Analysis of student drawings shows that most students in our study did not have a stable, coherent understanding of IMFs as interactions between molecules. At least 55% of the students in our study unambiguously represented each IMF an interaction or bond within a single molecule, while only 10–30% of students represented each IMF as an interaction between molecules. Furthermore, the majority of students (59%) were not consistent in the way that they represented the different IMFs (as within or between). That is, their representations varied depending on the IMF. Student written descriptions of intermolecular forces were typically quite ambiguous, meaning that it was not possible to determine from the student description alone whether the student understood IMFs as bonds or interactions. It was only when the student's representation was consulted that we could determine whether a particular student had an appropriate understanding of IMFs. We believe that in situations where spatial information is crucial, free-form drawn representations are more likely to provide meaningful insight into student thinking.