This spring I am doing something new in my sophomore inorganic class. Before I go into detail, a little background is needed. This class has a fairly academically diverse population. The prerequisite for the course is General Chemistry II. I have senior biochemistry majors that have had two semesters of P-chem as well as first year students that have only had General Chemistry II. I also have a fairly high population of chemical engineering majors. As I said, academically diverse.
One of the sections of the course that has always proven to be a challenge is the section on descriptive chemistry. I mentioned last year (https://www.ionicviper.org/forum/novel-instructional-methods-studying-c…) that I was adopting some of Fred Basolo's ideas in a revamp of my descriptive section. I did not see any significant changes in the results on the exams for that section. In particular, predicting reaction products continued to be a struggle. While I am still to stubborn too abandon the descriptive section entirely, I do think some change is in order.
I was inspired by Adam Johnson's LO (https://www.ionicviper.org/class-activity/generating-lgos-salcs), the related J. Chem. Ed. article and Gerard Rowe's LO expaning on Adam's LO (https://www.ionicviper.org/classactivity/understanding-hypervalency-act…). I've always felt that my coverage of MO's could be increased in this class and that my discussion of hypervalency was weak at best. But to include these concepts I will have to introduce group theory, a topic I have exclusively covered in my senior course. I am planning on a brief introduction to group theory and I will not be introducing all of the symmetry operations. Students should be able to determine point groups of simple molecules after our discussion. We will then apply this to developing molecular orbital diagrams using the techniques outlined in the aforementioned LO's. I am also including a computational lab for the students taking lab (about 1/3 of the class).
I'll be starting this material in late February/early March and I am very excited to see how it goes. I am a bit nervous because this year is the largest number of students I have ever had in this course. Having seen some of the preliminary data on a survey conducted by the ACS exam institute, I know this will put me more in line with what is being covered in other sophomore level courses (66% cover group theory to some extent).1 I also think this will be something that will make descriptive chemistry a bit more tolerable. I typically had one entire exam that was almost exclusively on descriptive chemistry. By watering it down with a little group theory and MO's (how strange does that sound?) I hope the students will find descriptive chemistry a bit less intimidating. The descriptive exam has the reputation of being my most evil exam. We shall see if this takes away some of that aura of doom. I'll update you once I see the results.
1Results of the recent survey on topics covered in sophomore inorganic were provided by Barb Reisner and will be available to the community at some point. These results will provide the framework for the new sophomore inorganic exam from ACS.
I look forward to seeing how it goes! I've been inspired by that conversation with you and Joanne to maybe try to get my advanced intro kids to do a little baby-symmetry-and-MO-stuff....we'll see...hopefully, it will be something interesting enough to post here!
I think the symmetry concepts can be useful to students in a number of ways. It just gives them another organized way to describe and think about 3 dimensional objects; so, in this way it can be useful no matter what they end up doing.
Kurt
I think symmetry is a fantastic topic that should be a part of every Inorganic class. Of course it gets REALLY cool when you can lead students through from the symmetry operations into point groups all the way through the matrices and character tables, BUT just doing the operations and point group assignments has tremendous benefits, IMO.
The excersize of seeing symmetry, finding operations, and identifying point groups is probably the best way to build 3-dim visualization skills. I tell the students it may not matter whether you can identify a molecule as D4h in 5 years, but you will have developed parts of your brain that are CRITICAL for virtually all fields of chemistry that will stay with you forever.
Those problem sets with 20 different, interesting molecules to identify guarentee students will spend hours making their brains hurt trying to think in 3-dimensions. Sure, let them use model kits (or just gum drops and toothpicks), there's no better skill'n'drill for building this kind of neural networks in their little brains. Plus they get to see all those really cool molecules we love (staggered ferrocene or bis(COT)Ce, M2X9, etc etc)
I added symmetry to an honors first year "enrichment" gen chem course for two years, and promised them "Trust me, you'll thank me when you get to Orgo", and I can't count the number of thanks I've received a year later (and times I've bitten my tongue to not say "I told you so".)
FWIW, the actual matrix math and characters is fairly easy for most students (compared to Calculus!), so going the next step to character tables and actual applications to vibrational selection rules, isomer identification, and MO theory isn't unreasonable. Skip the "Grand Orthogonality Theorem" but give them a clue where the characters actually come from, and show them some real applications. They dig it!
Also, in my experience (my own ugrad classes, and in teaching) is that IF a p-chem instructor covers symmetry it will be in an entirely useless way that confuses students, gives them no benefit of the 3-d skill building, and leaves them able to use the D-inifinity-h character table BY ROTE to say something trivial about a diatomic molecule.
When they see group theory and symmetry in an Inorganic class they say "oh wow, this stuff is really cool and useful".
[OK, one of my physical chem colleagues DOES do a good job with the topic, but he's (1) a theorist and (2) almost an honorary inorganic chemist]
Go for it, Chip!
Don
Thanks Don and Kurt. It went reasonably well. I am currently working on getting together an LO of the materials I used as well as some assessment. Spoiler alert: Students did pretty well with assigning point groups, not so well with being able to draw proper VSEPR structures.