We’ve just finished Week Four of the semester. Here’s what
I’ve been doing with my Elements theme in General Chemistry. On the first day,
the students introduced themselves by picking a “favorite” element and saying a
few words about their choice. Admittedly, this was probably a little forced for
some students who probably have never pondered such a question, but more on
that later.
There are some discussions specifically pertaining to the
Elements in the first week of class, but then the materials shifts to other
aspects that do not concentrate on the identity of the Elements, but on
elements of the Elements since I can’t resist the pun. To keep the theme alive
and in the student’s minds, I show two elements every class period from a
wonderful artist/cartoonist (Kaycie D.) from her website (you should check it
out!) Her drawings embody the elements in a humorous way that also highlights
their properties. Here’s one of them. (You should check out her website.)
My first Element assignment, creating an Infographic on a
known element, went quite well. Students submitted their infographics early in
Week Three and overall I’m pleased with the results. While a few students did a
rush job, many of them actually took the time to be creative so now I have some
sample infographics I can use to show my next class – I think I will do this
assignment again next semester in my chemistry for nonmajors class. (Last year,
it was a water-themed Infographic as a final project.) Some of the students chose the same element they had picked on Day One of class. It was great to see them creatively expand on their choice!
I’ve also creatively (or nerdily) attempted to inject Elemental language
into my problem sets and exams. My first problem set was titled “Element of the
Problem: Cobalt”. The students had to do some calculations on cobalt starting
with volume and density data from the WebElements site and compare their
numbers with the average mass listed on a periodic table. Clearly the two don’t
agree so the student calculate a percent error and suggest why there’s a
discrepancy. Then they are asked to add up the masses of protons, neutrons and
electrons of a particular isotope, and again think about why this mass differs
from the number in the periodic table. I’ve used versions of this assignment
many times over the years.
My second problem set, however, was created from scratch
last week. It is called “The Magnificent Seven of Magnesium” in honor of the
movie coming out this weekend. I forgot to tell the students about magnesium’s
use as a fuse! It will come up again later in the semester. The actual problems
weren’t as creative (on my part) – they focus on the photoelectric effect, line
spectra and the de Broglie equation, basically to make sure the students
understand the basics! Often they mix up ionization energy and the work
function, even though the two are closely related. Photon wavelength and deBroglie
wavelength are another pair that students get confused by, even after my
repeatedly saying in class how and why they are different.
I’m pleased to say that I think my take-home Exam #1 went
smoothly. I did try to inject some creativity into one of the questions. It has
to do with a shady scientist named L. Luthor who claims he has invented a new
element named Kryptonium. (Note, it is not kryptonite – which would be an ore
of kryptonium. I’ll bring this up in class when we talk about ionic compounds.)
A sample provided to other scientists for independent verification (because
this is important in science!) finds that it is radioactive and releases
beta-rays, and is actually a very heavy isotope of a known element. The
students try to figure out the identity of the isotope, and explain why it
undergoes beta-decay. There’s also a half-life calculation.
Just this past Friday our class did the first part of my
Alien Periodic Table activity, where fifty years of history is simulated in
fifty minutes of class time. The students, are of course completely confounded
(they are warned beforehand) by the difficulty of the problem as they try to
make sense of these strange new elements. Monday is part two where they will
receive photoelectron spectroscopy data and this will culminate in the second
Element Assignment due a week later where they try to elucidate the Alien
Periodic Table. We’ll see how that goes.
All this is part of the plan to scaffold their final project
where they will invent a new element. I still don’t know how well that’s going
to work, but that’s why it is worth doing the experiment!
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