A Perspective for Structure--Property Reasoning to Explicate and Scaffold Thinking Like a Chemist

Chemical reasoning, and in particular structure--property reasoning, is an important goal of chemistry education. Johnstone's triangle (1982, 1991) is often used to explicate this type of reasoning. This triangle describes the multilevel thought chemical reasoning requires and shows why students find chemistry so difficult. However, this model gives little guidance for teachers and students on how to teach and learn structure--property reasoning. In this theoretical article, we propose an alternative model for structure--property reasoning which has three advantages compared with previous models, namely, more coherence between chemical concepts and the skill of reasoning, more horizontal coherence (coherence between the concepts), and more vertical coherence (coherence throughout the school years). In four cases selected from the Dutch secondary school chemistry curriculum, the model was used to show how it can guide teachers and students in teaching and learning structure--property reasoning, and to demonstrate these above-named three advantages. The presented model has various educational applications as a scaffold for students' reasoning, and as an instruction, design, and curriculum tool for teachers.