“What are we doing to help kids achieve?”
Here is the context.
- Students with little to no lab skills.
- Shortened class periods.
- Maybe some students who were not placed properly in the correct academic level of chemistry.
- Need to build proper evidence based arguments.
- Simple set up.
- Easy to modify for students who are absent.
As I have said in the past (see the link here), microscale chemistry is starting to play a major role in my classroom.
We are currently studying quantum numbers, specifically, Pauli Exclusion Principle, Hund’s Rule and Aufbau diagrams. Students have been able to provide the electron configuration and orbital notation for different elements. At the end of the day, we have not looked at experimental evidence. Is it really different from the Bohr model and can we show that in a high school classroom?
Figure 1: Holding a rare earth magnet next to a test tube of manganese(II) sulfate
The answer is “yes” through a simple experiment. Many people have looked at this. I got the following idea from Bob Worley (see his website and his Youtube channel). Students worked on the orbital notation for manganese(II) sulfate and zinc oxide. First, I mentioned that the +2 charge comes from removing electrons from the S sublevel for stability reasons. Next, we looked at how the manganese should be half filled D with five unpaired electrons if it follows Hund’s rule. The zinc should have a filled D with no unpaired electrons. These two are also examples of paramagnetic materials (compounds with unpaired electrons that attract to a rare earth magnet) and diamagnetic materials (paired electrons that weakly repel from a rare earth magnet). Students came in and got the data in about 2 minutes in their groups.
Figure 2: Model for Potassium Thiocyanate and Iron(II)sulfate reaction
Students made the connection between the experimental evidence and the quantum numbers demonstrating paired and unpaired electrons. Next, it was time to predict. What happens if I were to take iron(II) sulfate and react it with potassium thiocyanate in a small “puddle”? Would the magnet have an effect on the iron?
Figure 3: Iron(II) sulfate reacts with potassium thiocyanate. Does the iron react to the magnet?
Finally, we had time for one more experiment suggested by Bob. I bubbled some oxygen in some children’s bubble solution on a petri dish. We discussed how oxygen has some unpaired electrons. Sure enough, the rare earth magnet was able to nudge the oxygen bubble across the dish.
In the end, this was quick, fast, easy and provided a rich discussion for future experiments. Definitely an experiment that I will come back to. Stay tuned for more microscale.
Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories.
Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories. Construct and revise an explanation based on valid and reliable evidence obtained from a variety of sources (including students’ own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.