Understanding what happens at the particulate level when ionic compounds dissolve in water is difficult for many students, yet this understanding is critical in explaining many macroscopic observations. This article describes a student-centered activity designed to help strengthen students’ conceptual understanding of this process at the particulate level and translate this understanding to the symbolic level. In this activity, students use magnetic models to explore how mono- and polyatomic ions interact with water molecules and with each other. Manipulating the models addresses the common students’ misconceptions (1) that ionic compounds remain as ion pairs and (2) that polyatomic ions dissociate into individual monatomic ions. These models also help students see how water molecules orient around the individual ions. Writing dissociation reaction equations for the modeled dissolving processes helps students better understand the relationship between subscripts and coefficients in writing ionic equations. Post-test and final exam scores on questions related to the particulate and symbolic representations of the dissolving of ionic compounds show improved and retained understanding of this concept.
Ryan, S. & Herrington. D. (2014). Sticky Ions: A Student-Centered Activity Using Magnetic Models to Explore the Dissolving of Ionic Compounds, Journal of Chemical Education, 91(6), 860-863, DOI: 10.1021/ed300607a