Happy Mole Day

It’s the middle week of the semester. We don’t have a mid-semester Fall Break. And this year mole day is smack in the middle of the week. Our department student affiliate chapter has organized several fun activities. Liquid nitrogen ice-cream is quite popular. (I was in a meeting so I missed it.) There’s also lab-coat tie-dyeing. Personally, I prefer my pristinely white lab coat. As a computational chemist I don’t spend any time in lab running chemical reactions, although I have taught general chemistry lab and I have on occasion subbed in an advanced lab class for several hours.

 

I don’t have any mole-specific thoughts today. In G-Chem 1, we’re smack in the middle of chemical bond. I’ve been thinking about what we might omit if we moved thermochemistry from G-Chem 2 to G-Chem 1. Do we need to discuss the exceptions in electronic configurations? Do we need to discuss the kinks in the trend of first ionization energy across the row in the periodic table? Do we need to discuss hybridization of orbitals? Can we omit the photoelectric effect? In addition to discussing wave-particle duality, I use it as a springboard to introduce energy diagrams. I’ve been trying to include energy diagrams as much as possible: hydrogen atom (and Bohr model), photoelectron spectroscopy, electron configurations, and bond energy curves.

 

In P-Chem 1 we have just finished the hydrogen atom. I promised the students we’d be there by mid-semester so that we can get to molecules! With more electrons! Many of the students will also be happy to see the math load decrease. The next problem set will still be math-ugly (or math-elegant, depending on your point of view) because we’ll be covering the variational principle and perturbation theory. Once we get past the Born-Oppenheimer approximation, the problem sets will get much less math-intensive. We’ll draw pictures of models and try to extract conceptual information from them. But first students will need to get pass the dreaded Exam 2 coming up on Friday.

 

September was for getting settled in (and ahead) in my classes. October was when I wanted to start working on a research article. I have gotten started but it’s slow-going. I think I have most of the data tables done and I’ve outlined the key figure for the paper with lots of chemical structures and a bunch of arrows. But there’s still quite a-ways to go and it’s been hard for me to get motivated to write. I’d much rather spend time thinking about my classes, or two side-projects that I’ve been exploring that may turn into collaborations with experimentalists. So I am getting some research done, but it’s slow. I did spend a chunk of September training two new research students; the first month is full of “how do I do that again?” but I think they’re getting the hang of it now and are starting to produce their first tranche of results.

 

As we head towards cooler temperatures, and with thermochemistry still on my mind, I’ve been musing about the nature of hot and cold. What is cold? The absence of heat, I suppose; although heat is not a noun. Let’s just say that when heat flows out of the system, if that leads to a loss in thermal energy, then the system gets colder. The zeroth law is constantly trying to make the temperature uniform everywhere. That makes refridgeration a neat trick when you don’t want to be using blocks of ice to cool stuff down. I grew up with a refridgerator in the house so I don’t know what it felt like to be without one. You’d have to eat up your fresh produce quickly enough so it wouldn’t spoil. Higher temperatures mean chemical reactions are occurring more quickly on average! And what is temperature? It’s a statistical average of the thermal energy of gazillions of molecules – six gazillion if it’s a mole of molecules. Aha, I was able to tie this back to the mole. Happy Mole Day!