Although my role at Physics Today has me writing about many areas of physics, I’m most in my element when I cover work at the interface between physics and chemistry. As I’ve written in this column before, it was a chemistry class that first impressed on me the beauty of the physical sciences. To this day, though I understand the appeal of the physics of the extreme and exotic—black holes, high-energy particles, the origins of the universe—I’ve always been partial to atoms and molecules, the invisible building blocks of everything around us, whose myriad combinations give us the richness of our everyday world.
Much of that richness, of course, comes from the chemistry of carbon. And this month, not for the first time, I wrote about an unusual phenomenon discovered in a large organic molecule. You don’t need to know much about organic chemistry to understand the story—at least, my goal was that you wouldn’t have to. I know that organic chemistry can be intimidating to a lot of nonchemists, due in part, I think, to how it’s taught to undergraduates in the US. Even if you haven’t studied “orgo,” you may know the class by its reputation as the tedious, grueling ordeal in which premed students sink or swim based on the ability to fill their brains with multitudes of disparate and mostly useless molecules, reactions, and mechanisms, all learned through hours of daily rote memorization.
That wasn’t my experience. But I wasn’t a typical orgo student. I took the class in my senior year, when I’d already taken not only the full complement of other advanced chemistry classes (orgo wasn’t formally a prerequisite for any of them, although it probably should have been) but also a major’s worth of math classes and no small amount of physics. I was used to viewing science as a framework of concepts, not a set of facts and procedures. There’s no way to learn topology, say, by just memorizing everything.
I instinctively approached orgo the same way, and it worked: All those reactions and mechanisms had a logic to them. Organic molecules are all made up of the same few elements—carbon, hydrogen, oxygen, and nitrogen, with occasional guest appearances by sulfur and the halogens—and there are only so many ways they can behave. In every arrangement of atoms and chemical bonds, the nuclei and electrons are dancing a version of the same dance. Once I internalized how the dance worked, I could look at a representation of a mechanism in my notes, visualize the dance steps in my head, and think, “Yes, that makes sense.” I spent a few hours doing that before each exam, and I aced all of them.
Looking back, I can point to concepts I’d learned in other classes that primed me for understanding the dance steps. I could conceptualize electrons as delocalized wavefunctions (quantum mechanics), visualize phenomena that are inherently three-dimensional (electricity and magnetism), consider symmetry (group theory), and build intuitive frameworks for things I couldn’t see and could at best approximately draw (pretty much every math class past calculus).
But my biggest advantage, I think, was in realizing that there was a dance to be learned in the first place. No one had told me that—or let on that there was any more to the subject than memorization—so it seemed to me like a profound revelation at the time. The whole class seemed like a big trick question, presented as being about one thing when it was secretly about something else entirely, and success depended on realizing that on your own.
Nowadays, it looks like online fora and study guides are starting to let students in on the secret: that if you’re trying to learn orgo by memorization, you’re doing it wrong. I’m glad, and I hope it means that more of today’s students are seeing the same elegance in the subject that I saw.