Intermolecular Forces and the Languages of Chemistry

The concept of intermolecular forces is challenging because students often revert to intramolecular explanations when discussing macroscopic properties. This set of activities from our general chemistry course aimed to use the different languages of chemistry to help build a more solid, multilevel understanding of intermolecular forces. Through the symbolic language of graphing, students were first asked to explore the relationship among melting point, molecular weight, and structure. Macroscopic language was used during a lab activity where students hydrogenated common kitchen oils and saw a change from liquid to solid. In another activity, students employed atomic/molecular/particulate language in building models and thinking about the interactions between molecules. They were asked to make use of all three languages in examining the intermolecular forces relevant to the melting points of fatty acids and triglycerides.