A First Week of Gold

“Gold of all the metals is the most useless in Physick, except when considered as an antidote to poverty.” – Etienne Francois-Geoffrey (physician and chemist)

I always look with excitement to the first week of classes! It was always busy as usual, my throat felt a little sore, and I was more tired at the end of each day. I think it is because I’m not used to as much talking and standing (while gesticulating wildly about chemistry). During the summer, there is more sitting in solitude in front of a computer screen. I am teaching General Chemistry (G-Chem) and Physical Chemistry (P-Chem) this semester. My G-Chem class is oddly skewed with 75% women (normally closer to 60%) while my P-Chem class is slightly over 50% women, closer to the norm.

The opening quote comes from the first chapter of Periodic Tales by Hugh Aldersey-Williams. One of my colleagues, who heard about my planned Elements theme to be threaded throughout my G-Chem class lent me the book just before the weekend. The first section is titled El Dorado – “the Golden Man”. I’m barely 25 pages in, and I’ve found all sorts of interesting vignettes that I can use in my classes. The chapter opens with the sculpture Siren which is apparently a life-sized gold statue of the model Kate Moss, in the British Museum. Maybe it should be La Dorada. (I’m learning Spanish on the side.)

If I had started on the book earlier, I might have used this in my class on Friday where we discuss measurements, S.I. units, scientific notation, conversion factors, precision & accuracy, and more. For many years, I’ve used Archimedes to launch the discussion. (Here’s a link to a Lego Archimedes video!) We talk about density and how to check if a crown is indeed worth its weight in gold, or alternatively gold-plated over a cheaper metal. Apparently Siren was designed to weigh the same as Kate Moss, which means that it isn’t pure gold. If the volume of Kate Moss was her weight in gold, she would be tiny. The next time someone uses the expression “worth [one’s] weight in gold”, I’ll be ready with a discussion about Siren. Or maybe I could quip about whether we should use osmium instead!

For many years, we would do a calculation in class to compare the density of a pure gold crown to that of an alloy and calculate the water displacement in both cases. But then we stopped there. Over the last couple of years, I’ve added a “design an experiment” component to allow the students to see that even if one knows “what the numbers should be like”, that the actual design to allow more precise and accurate measurements can be tricky. I ran out of time this year and didn’t get to the question of measuring one’s own density (I pose the question “How Dense are You?” usually to nervous laughter when the students get the joke) and comparing this to the definition of BMI (body mass index). Maybe next year I will use Siren as a class example.

This semester my plan in G-Chem is to thread an “elemental” theme through the semester culminating in a final project where the students propose the invention of a new element. In my first meeting with students (as part of an icebreaker), students were asked to choose a favorite (known) element and explain their choice. I’ve done this for several years, and inevitably there are students who choose gold. This year I had one student choose Europium (because she would like to visit Europe) and another chose Yttrium. (Oxygen was the most popular this year.) I learned in the opening pages of Periodic Tales that apparently Europium is used as a luminescent dye in the Euro bank notes, apparently the whim of a “humorous bureaucrat”. I also learned that Svante Arrhenius (1903 chemistry Nobel prize winner), who studied electrical conductivity in solutions, made an estimate of the amount of gold in the oceans; and that apparently Fritz Haber (1918 winner) apparently outfitted a ship to take measurements in the Atlantic Ocean.

Gold will feature again in my G-Chem class this week. We will be looking at experiments determining the structure of the atom. Rutherford’s experiment shooting alpha-particles at gold foil will feature prominently in our discussions! Gold hasn't shown up in my P-Chem class (Quantum Chemistry). We just finished a class on the Bohr model and derived the Rydberg equation based on Bohr’s simple model of hydrogen as an electron orbiting a proton with quantum restrictions on its orbits to be an integer of some deBroglie wavelength. In Periodic Tables, there’s an interesting vignette on Bohr melting down the gold Nobel medals of Max von Laue and James Franck so they would not fall into the hands of the Nazi regime. He used aqua regia! After the war, the Nobel Foundation reminted the medals. Maybe I can mention this in my next class.

Looking forward to Week 2 (after a Labor Day holiday)!