Connecting the Visible World with the Invisible

Research suggests that connecting the visible (macroscopic) world of chemical phenomena to the invisible (particulate) world of atoms and molecules enhances student understanding in chemistry. This approach aligns with the science standards and is fundamental to the redesigned AP Chemistry curriculum. However, chemistry is usually taught at the abstract symbolic level, rarely incorporating particulate-level instruction. This article addresses that shortcoming by describing how to use particulate diagrams in a chemistry course. Using particulate diagrams in such topics as nature of matter, chemical/physical changes, ionic compounds, balancing equations, colligative properties, and acids/bases enhances students' critical-thinking skills as they experience the science and engineering practice of Developing and Using Models. The diagrams were incorporated into pre- and post-assessment, lab questions, and explanations given in class.