Students’ Sensemaking of Electrostatic Potential Maps within Substitution and Elimination Reactions

Abstract

Reaction mechanisms are a difficult and foundational topic students encounter in organic chemistry. Consequently, students often memorize when attempting to learn the array of organic reactions. While interventions have been offered to encourage mechanistic reasoning as an alternative approach, a deeper struggle pertaining to students’ comprehension of the underlying chemical principles driving reaction mechanisms is still prevalent. In this study, electrostatic potential maps (EPMs) were explored as a tool students could use to reason with some of these principles to predict and explain the outcomes of a reaction. Through semistructured interviews, 19 students’ sense-making strategies were recorded and analyzed to uncover how they used the features of EPMs with concealed atomic identities and how they reconciled their answers once the identities were made explicit. Analysis revealed that the absence of atomic identities generated approaches centered around electron densities and their utility in predicting reaction mechanisms and outcomes. As the atomic identities were revealed, the majority of participants reverted to memorized mechanisms, while six participants attempted to relate the atomic identities to the interactions of the electron densities. These findings suggest utility in implementing EPMs in the organic chemistry curriculum and offer a feasible intervention to promote sense-making when students reason with organic reactions.