Conjugation Amplifies Complexity: A Comparison of Problem-Solving Strategies Across the Organic Chemistry Sequence

Resonance structures are central representations in organic chemistry that explain trends in acidity, reactivity, geometry, and stability. Despite being a central representation, prior research findings have shown that students' productive application of resonance as a resource is context-dependent. This research reports findings from a cross-sectional analysis study investigating how Organic Chemistry I (OC1) and Organic Chemistry II (OC2) students use resonance structures to describe acid-base properties, chemical shifts, and geometry. Six students from OC1 and six from OC2 participated in semistructured interviews to capture their problem-solving pathways. Each prompt was designed to be answered using resonance structures. OC1 students, who noted resonance, were less successful with drawing and applying resonance structures than OC2 students, as expected. However, both cohorts used resonance structures to a limited extent, despite the similarities of molecules presented within each prompt. Resources that do not require structural manipulation, such as s-character and electronegativity, were commonly activated instead of resonance across both courses.