Friday, February 25, 2011

Web applications in KemiKS: Quiz and Hückel

This week, we have tried three new visual features in KemiKS.

a) The students were strongly encouraged to use Maple in the solution of one problem, where they are supposed to draw the wavefunction of the hydrogen molekyle ion. This exercise was previously solved by hand, but now was supposed to be solved by using Maple. The students responded positively to it, although they had lots of problems in remembering how to use Maple. But when they finally had plotted the wavefunction, they really liked the fact that they now had created themselves the figures shown in many textbooks.

b) Janus had found a website at, with a good discussion of atomic orbitals up to f-orbitals and a nice quiz. The student were asked to do the quiz in the first exercise class on monday as a repetition of what they had learned in the week on atomic orbitals. We will later in week 7 follow up on this idea and give the students in the beginning of the week a quiz on the key points of the week, which they probably will not be able to answer. At the end of the week, the students will then repeat the quiz and hopefully can see what they have learned in this week. Janus will look for appropriate tools in order to make a quiz with high score and solutions outside of Absalon.

c) as illustration of the discussion of the Hückel method, we have now incorporated two java based Hückel programs (see description in previous blog), which can be run over the net or can be downloaded and run directly on ones computer. This was thought to have the big advantage that we can study much larger systems, which previously were out of question, when one had to diagonlize the Hückel matrices by hand. The students were then asked to use these tools in two of the problems of this week. One problem was newly made and the other was modified so that the students now use these Hückel programs instead of doing it by hand. Talking to the teaching assistants helping the students the response is mixed. On one hand the Hückel programs are nice tools, but the danger exist that the students loose the understanding of how the Hückel matrix should look like, because in these Hückel programs it is generated automatically for them after drawing the molecule in the GUI. Therefore, it might actually didactically more effective to let the students write down the Hückel matrix by hand and then use Maple to diagonalize it, which is without computers typically the limiting factor or to have to exercises: one with the Hückel matrix by hand / Maple approach for a medium size molecule and one with the Hückel programs for a large molecule.


Jan Jensen said...

"but the danger exist that the students loose the understanding of how the Hückel matrix should look like"

One suggestion is to ask the students to use the Huckel program first to generate data, and then ask them to explain the data using Maple.

The "how do you explain ...?" approach often works better than the the "what do you predict ...?"

Unknown said...

Great suggestion Jan,

I think what was learned in KemiKS was indeed valuable for further work towards "Den Gode Uddannelse".

I still stand by my statement that a simple "do-it-yourself" on ethene and explain what the outcome is, will bring a greater understanding of the output of these programs which in turn can be used to answer more interesting and chemically relevant questions, than say: what is the orbital energy.