Teaching Relativistic Effects in Undergraduate Chemistry Education: A Fireworks-Based Electronic Structure Perspective

Abstract Relativistic effects are essential for explaining heavy-element chemistry, yet many undergraduate chemistry students perceive them as physically abstract and detached from chemical reasoning. We hypothesize that this persistent barrier arises not from the intrinsic difficulty of relativity but from a structural issue in instruction─namely, how relativistic effects are introduced and linked to the breakdown of the nonrelativistic electronic structure description for heavy elements. To address this issue, we designed an instructional module that presents relativistic effects as a conceptually continuous extension of nonrelativistic electronic structure theory. Using fireworks and flame-test colors as motivating chemical phenomena, students compared nonrelativistic and scalar-relativistic descriptions and examined how relativistic effects alter orbital energies and optical transitions. The module was implemented in a single undergraduate quantum chemistry course, and students’ responses were analyzed using Likert-type self-assessment items, multiple-choice questions, and responses to open-ended questions. The results indicate increased self-reported confidence and suggest that some students began to connect observable color differences with underlying changes in electronic structure. Because the study was conducted in a single class without a control group, the findings should be interpreted as preliminary evidence of educational usefulness rather than definitive evidence of learning gains. This work provides an exploratory instructional pathway for repositioning relativistic effects from separate physics to an explanatory concept for heavy-element chemistry in undergraduate chemical education.