Chemistry—A Modeling Approach to Periodicity & Bonding

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Leaders: Donghong Sun, Tammy Gwara

The periodicity of elements and chemical bonding are essential topics in introductory chemistry. However, when we teach these topics, we frequently rely on anthropomorphizing the particles in order to help students remember: “Sodium wants to lose this extra electron because it’s happier with a full valence.” Students memorize the conventions but are unable to put meaning to what they are doing.

We will demonstrate how the model of electron energy levels can be developed from patterns found in ionization energies of elements. Students will then apply this empirically developed model to explain the periodicity in ionization energy and atomic radii, as well as common charges of monatomic ions and the nature of ionic bonding. We will also develop a model to explain covalent bonding, using empirical evidence of compound formulas to derive the “combining power” of particular elements.

The workshop will follow the modeling cycle: developing the model based on evidence, deploying the model to make predictions, and then evaluating the model for flaws and developing the need for a more sophisticated model.