Unit Cell Modeling

unit cell models

This year my students experienced something a little new to them on the Chemistry Olympiad. It was a question about the crystal structure of a mineral. I have not been teaching the “unit cell” concept in great detail and started to reevaluate my unit on liquids and solids. This question has been appearing on the semifinal exam of the Chemistry Olympiad for a few years but not the local exam until this year. I actually like it when something like this happens. It allows me to reevaluate what I am teaching in class, provides me an opportunity to learn new things, and brings new material into my curriculum. 

I spent a great deal of time last summer looking over several books that covered the structure and types of solids in great detail. I had not looked at this material since my undergraduate days and suddenly found myself learning (or should I say relearning) some great material. I was really excited to prepare a bunch of new lessons and was being amazingly productive about it. I had stayed away from a great deal of this material because it was so hard to comprehend for high school students. It is difficult for my students to visualize the intricacies of unit cells. But one of my motivations came from two students in my class this year that were very talented artists and agreed to make me a nice set of drawings for use in a lecture. Having these most excellent drawings I figured I could revisit the subject with more success then in the past. I also envisioned going very “Old School” and having the kids build a large number of models out of Styrofoam balls, toothpicks, and string. It might be a very old approach but it seems to work well for my students to build models. I was also getting excited about writing this up for ChemEdX as a discussion of always reconsidering your curriculum. Then something very interesting happened. 

I was looking over the articles in the Journal of Chemical Education and found an article called “
”. It deals with the use of a 3D printer to make models of crystal structures. I had not thought of this and it seems like a novel and very practical approach for the topic. I do not have a 3D printer (and not much danger of the school jumping up and putting one in my classroom on a moments notice) but there is one in our computer lab and several of my students have access to it. So I am excited about having them try to make several of the structures discussed in the article and see where it goes. There is a very large library of structures available online for public use.

I am a big fan of model building and want to extend any way I can with something like this. I really recommend you take a look at this article.