In this literature discussion, students are asked to read an article describing a series of uranyl halide compounds that contain an alkali counterion that interacts with one or more of the uranium's ligand atoms. This paper stands out as a great example of the binding preferences of acids and bases, and can be explained very well using simple HSAB concepts. Also notable in this paper is the fact that the authors claim that HSAB concepts explain their results very well in the introduction, and then only bring it up again almost as an afterthought in the short discussion section at the end of the paper.
A student should be able to rank Lewis acid and bases in terms of relative hardness
A student should be able to interpret X-ray crystallographic structural data and identify structural motifs
A student should be able to explain the affinity that atoms have for one another in terms of HSAB theory
This activity is fairly straightforward, and my students needed little help working through the discussion questions. For most students, this was the first time they had seen molecules represented as thermal ellipsoids, so they had a little trouble identifying the atoms inside molecules, but everyone got it by the end of the class.
Students were evaluated on how completely they answered the pre-class reading questions.
In-class discussion questions were collected at the end of the class period. For these, students worked in groups of 2 or 3.
Most of the students grasped the major concepts by the end of the class, though there was a lot of initial confusion as to how to make sense of all the structural data in the paper.
The biggest hurdle students had to overcome was shifting their thinking from absolute terms (e.g., sodium is hard) to relative terms (e.g., sodium is harder than potassium). Once they did this, the rest of the activity becomes very simple.