This paper describes an interdisciplinary investigation of students' usage of ideas about energy from physics in the context of introductory chemistry. We focus on student understanding of the idea that potential energy is a function of distance between interacting objects, a concept relevant to understanding potential energy in both physical and chemical contexts. Data from student responses to written surveys and focus-group interviews reveal that students do not spontaneously make connections between ideas they have about energy from physics classes and the understanding of energy that they develop in chemistry. We describe the development of a sequence of questions that appears to aid students in drawing these connections appropriately. We also document students' as they are confronted with and struggle to resolve the mismatch between their energy ideas from physics and chemistry.