Lesson 5: Resonance and Lewis Acids and Bases

Video content, worksheets, practice problems and more

In Lesson 5, we focus on resonance and its implications in understanding Lewis acids and bases. We begin by reviewing the concept of resonance, emphasizing the importance of electron delocalization in stabilizing molecules. Students revisit how to draw resonance structures, adhering to the rules that ensure the same number of electrons and consistent positions of nuclei across different structures. Examples such as benzene and the acetate ion illustrate the practical application of resonance in organic molecules.

Next, we delve into Lewis acids and bases, building on the foundation laid in the previous lesson. Lewis acids are defined as electron pair acceptors, while Lewis bases are electron pair donors. We explore the relationship between resonance and Lewis acidity/basicity, showing how resonance stabilization can affect the strength and reactivity of Lewis acids and bases. Examples like aluminum chloride (AlCl3) as a Lewis acid and ammonia (NH3) as a Lewis base are used to clarify these concepts.

We then integrate the two topics by examining how resonance structures influence the behavior of Lewis acids and bases in chemical reactions. Students learn to identify potential sites of electron pair donation and acceptance by analyzing resonance structures. This section includes practice problems where students draw resonance structures and predict the behavior of molecules in Lewis acid-base reactions.

To solidify understanding, we summarize the key points, highlighting the interplay between resonance and Lewis acidity/basicity. A preview of the next lesson, which will cover isomerism and stereochemistry, is provided. Practice problems and homework assignments are given to reinforce the concepts covered, focusing on drawing resonance structures and applying them to predict the behavior of Lewis acids and bases. This lesson aims to deepen students' comprehension of resonance and its critical role in determining the properties and reactivity of Lewis acids and bases.