Secondary students' mental models of atoms and molecules: Implications for teaching chemistry

This interview-based study probed 48 Grade 8–10 students' mental models of atoms and molecules and found that many of these students preferred models that are both discrete and concrete. Modeling is a powerful skill that defines much of the scientific method; however, most younger science students have difficulty separating models from reality. Language that is common to both biology and chemistry (e.g., nucleus and shells) is a major source of confusion for some students. Several students concluded that atoms can reproduce and grow and that atomic nuclei divide. Electron shells were visualized as shells that enclosed and protected atoms, while electron clouds were structures in which electrons were embedded. These, and other alternative conceptions may be generated during discussion as a result of semantic differences between teacher and student language. Students expressed a strong preference for space-filling molecular models and their conceptions of the models used in chemistry reveal much about the difficulties that students face as they try to assimilate and accommodate scientific ideas, and terminology. It is recommended that teachers develop student modeling skills and that they discuss analogical models, including shared and unshared attributes, with their students. © 1996 John Wiley & Sons, Inc.