Research into Practice: Visualising the Molecular World for a Deep Understanding of Chemistry

Why is chemistry so difficult? A seminal paper by Johnstone (1982) offered an explanation for why science in general, and chemistry in particular, is so difficult to learn. He proposed that an expert in chemistry thinks at three levels; the macro (referred to as the observational level in this article), the sub-micro (referred to as the molecular level here), and representational (referred to as the symbolic level here). The observational level involves chemistry that is visible and tangible, incorporating what we can perceive with the senses. The molecular level of understanding consists of mental images that chemists use to imagine and explain observations in terms of atoms, ions and molecules. Observed phenomena and molecular-level processes are then represented in terms of mathematics and chemical notation at the symbolic level. In the early 1990s the VisChem project was funded to produce a suite of molecular animations, depicting the structures of substances and selected chemical and physical changes (Tasker et al., 1996), to address student misconceptions identified in the literature. For instance, only VisChem animations portray the vibrational movement in solid substances. This is important because this movement is correlated with temperature, and students need to understand this to interpret the significance of melting and boiling points in molecular-level terms. The need for a chemistry student to move seamlessly between Johnstone's three "thinking-levels" is a challenge, particularly for the novice. The author's work in the VisChem project indicates that animations and simulations can communicate many key features about the molecular level effectively, and these ideas can link the laboratory level to the symbolic level. However, the project has also shown that new misconceptions can be generated.