This study investigated the conceptual challenges faced by Grade 12 STEM learners in mastering the electronic structure of atoms, encompassing the quantum mechanical model, energy levels, orbitals, sublevels, electron configuration, and quantum numbers. The research also examines learners’ self-efficacy in understanding these topics. A needs assessment questionnaire, validated by both subject-matter and methods experts, was administered to evaluate learners’ comprehension, alongside a self-effic