Abstract:

The Flipped Classroom methodology popularised by Bergmann and Sams is known to increase the interest and performance of the students. Traditionally, students learn first in the classroom by following the exposition of the professor and then by revising, analysing and synthesizing the information by themselves. The Flipped Classroom approach reverses the traditional activities so that the students work before the lesson using the material provided by the professor and then, in the classroom, they discuss the topics with professors and peers or set out the problems they have found, if any. In this new context, the provided information becomes essential and it should be carefully elaborated. The material usually includes pre-recorded lecture videos, online resources, experimental and/or computed data and text documents. We propose the application of the “Flipped Classroom” procedure to the writing and resolution of secular determinants implementing the Hückel treatment for π-delocalized systems in a Quantum Chemistry course placed in the second year of the Chemistry Degree. Our experience teaching the Hückel method along the last years leads us to think that even the students who solve the problem correctly do not understand the severe approximations they are assuming. Thus, they believe the null overlap assumption for atoms bonded to each other could be applied in a general way, as they forget that it is a very poor approximation only used by simple semiempirical methods. In order to emphasize the importance of the approximations in the resolution of Hückel exercises, we propose that the students use a modified Hückel method that includes non-zero overlap integrals between neighbour atoms. Video tutorials with a step-by-step resolution of secular determinants by using the original Hückel method will be at disposal of the students, as well as different links with solved examples for model molecules. Once the students understand the original method, the modified version is proposed to solve the same systems.
The discussion of the results obtained with the original and the modified methods is performed in the classroom in small groups.
The achievement of objectives of this project was tested through two different procedures. On one hand the students were asked about the flipped classroom methodology. All the participating students appreciated the experience. Additionally, the academic results were evaluated introducing a set of questions in the corresponding exam.

Keywords:

Flipped classroom, Hückel method, Quantum chemistry.