By James Ashenhurst
The Six Categories of Knowledge in Organic Chemistry
Last updated: March 27th, 2019
Here’s an idea I’m playing with: there are six types of things to learn in an organic chemistry course, and they all build on each other.
Vocabulary includes the words we use to describe chemical phenomena. This includes the names of elements, functional groups, etc. as well as the definitions of things – like dipole moment, melting point, bond, diastereomer. If it has a definition, it belongs in the “vocabulary” category. Moon.
Conventions include the visual symbols used to represent chemical phenomena, like line formulas, different types of arrows, wedged/dashed bond notation, and so on. This category also includes the rules of nomenclature, which are the agreed-upon conventions for naming chemical compounds. Moon? Moon!!!
Facts are observable, measurable, repeatable phenomena. Facts are concrete. Melting points, pKas, bond strengths, and chemical transformations are all examples of facts. This is the underlying reality that we map our vocabulary and conventions on to. When we look up at night we all see the same moon, whether we name it in English, French, or Cantonese.
Concepts are useful abstractions of facts. Concepts are simplifying: they condense a vast number of facts into generalizations. “Like dissolves like” is a perfect example of a concept. “Opposite charges attract” is another. Concepts can also show the relationships between facts: “The longer the carbon chain, the higher its boiling point”. Concepts point to deeper principles. They allow us to make predictions about phenomena before we actually do the experiment. Knowing that “like dissolves like”, for instance, allows you to make predictions about the solubility of cesium fluoride in water before you do the experiment. Moons orbit planets.
Formulae are pretty self-explanatory. They are numerical relationships between measurable quantities, like mass, volume, optical rotation, and so on. Another way of looking at formulae is the numerical expression of concepts. For instance, in physics, the force of an object is directly proportional to both its mass and its acceleration. Given two of those variables, we can calculate the third. (Permit me a temporary moment of physics envy: oh, to have clear numerical relationships between properties! You’ve probably realized this by now: organic chemistry ain’t physics.)
Finally, all of these would ultimately be pointless to us without skills. Skills are the application of facts, concepts, formulae, (and even conventions) towards a particular end, often to solve a problem. Some examples: naming a molecule; calculating a concentration; converting a line drawing to a Fischer projection; planning a synthesis; predicting the course of a reaction. We learn a language to communicate. We learn chemistry, physics and other sciences to gain the skills to solve real-world problems. Let’s put a man on the moon!
When you break the course down like this, it becomes very apparent (to me, anyway) why organic chemistry is hard. The course is extremely heavy on vocabulary, conventions, facts, concepts, and skills. Furthermore, organic chemistry doesn’t have a lot of formulae. This actually makes it tough – formulae are simplifying. The lack of a lot of formulae in organic chemistry means that things are often complicated. One of my favorite quotes: “A science with more than seven variables is an art”.
I’ll leave you with this thought: each category requires a different strategy for effective learning. I’ll go into more detail in future posts.
PS – There are probably some gaping holes in these generalizations – the line between facts and concepts, for instance, can get pretty blurry – any ideas for improvement out there? What am I missing?