Submitted by Adam Johnson / Harvey Mudd College on Fri, 01/27/2017 - 14:19

Inorganic Chemistry Trainwreck

The great experiment, 2017

Time will tell if this was a trainwreck or a trainwreck-narrowly-averted, but let me tell you about my junior/senior level inorganic chemistry class for Spring 2017. I restructured both the lecture and laboratory this year to make it simultaneously easier for me to deliver the lab content, and also to link the two separate courses more closely together. My first 2 experiments are the classic syntheses of metal acac and arene chromium carbonyl complexes. In the past I have been disappointed in the students’ ability to interpret standard characterization methods for these molecules: UV-Vis, magnetic susceptibility, and M-CO IR. The students can use the techniques, but did not understand correct application of the UV-Vis, or correctly interpret magnetic properties or IR spectra as the theory was not ever fully developed until mid- to late in the semester.

So, I had the brilliant idea to start my class with crystal field theory, magnetism and group-theory-based IR spectroscopy.

My class is an “advanced” class, meaning most (70%) students have taken thermo, kinetics, group theory and quantum before. Most have also had a semester of “basic” wet inorganic (equilibrium, acid base) in our analytical sequence. So I decided to go for it, laying out an unsupported cantilevered ledge of knowledge, with the hope of being able to go back after the first 3 weeks to backfill and support their understanding with theory and examples.  Here are my first 9 lecture topics, and list of the LOs I’ve used (usually in part, and not the whole LO) so far or plan to use:

1: intro to course (first day stuff) and intro to coordination complexes (first day quiz, CBC - only VN and LBN for now)
2: CFT for octahedral and square planar (frosh chem CFT; heavily modified; just the CFT derivation)
3: terms and Tanabe-Sunago diagrams (Sheila Smith’s and Sabrina Sobel's introductions to Tanabe-Sugano diagrams)
4: TS diagram interpretation, magnetic properties, Td crystal field (Amanda Reig's LO on Ruby; Matt Whited has one too!)
5: Magnetic susceptibility by Guoy balance and NMR (my historical perspective on the Evans method, and my other one showing how to use the technique)
6: symmetry (symmetry challenge, 2017)
7:  point groups and character tables
8: IR of metal carbonyls (reduced mass calculations LO, and Maggie's BO LO)
9: IR of metal complexes (isotopic substitution LO, and another on vibrational modes)

So far, actually, I don’t think this is going to be the train wreck I feared it might. Students are willing to suspend disbelief that I will eventually be able to go back and define what symmetry labels are, or what high spin/low spin means, or why ∆o changes with different ligands. And I do have to go back and fill that in; some of it will come sooner with the symmetry module, while some will come much later (I’m looking at you, spectrochemical series).

Stay tuned. If Flo lets me, I’ll report back on how it went!


Flo / Slytherin' State

Why Adam, of course I'll let you report back. I enjoy watching a good train...errr hearing about the wonderful changes you or anyone else has made to their inorganic courses.

Wed, 02/01/2017 - 17:27 Permalink