This past March, I ran a multi-day poll on Twitter that was designed to be a fun way to determine the “best” element on the periodic table. I’m sharing about the poll here on ChemEdX in case others might want to try something similar in their classrooms.
My students just finished an activity about isotopes. Each year there is always one or more student who ask about the mass of isotopes. How do scientists solve for that mass experimentally?
After spending the start of the year using a modified version of the Modeling Instruction curriculum (density and physical properties, followed by gas laws, followed by energy and phase changes), we don’t actually start talking about what’s inside atoms until December. I love that by this point students are already familiar with some of the habits of mind needed to reason abstractly about atoms -- thinking proportionally, explaining macroscopic observations at the particle level -- and we are ready to layer on both more abstraction and the symbolic level. By January, we are ready to explore electron configurations.
This is the first isotope activity I have tried where the students can look inside the model that resembled the atom and find information that reinforced what an isotope actually is. Furthermore, the quantitative data forced them to examine beliefs about different types of averages and what the numbers really mean.
If your not familiar with the video series "The Mystery of Matter, Search for the Elements" then I highly recommend their use as part of your curriculum. The Mystery of Matter: Search for the Elements is a PBS series about the amazing human story behind the Periodic Table. The videos, most of them 4-12 minutes long, draw on the interviews, re-enactments, animations and photographs that were shot and collected for the PBS series, with supplementary animations and images as needed. In all, the videos make up about three hours of programming. I shared several of the video clips with my high school students and they really seemed to enjoy them mentioning the reason was because the videos were done using actors to tell the stories and it was similar to watching a movie.
After receiving positive feedback from Peter Mahaffy, the IUPAC project co-chair of Isotopes Matter, I decided to add an additional component to the original isotope assignment I posted. The second component of the assignment focuses on the applications of both radioactive and stable isotopes using the interactive IUPAC periodic table.
Isotopes Matter is a digital learning tool, developed by IUPAC Isotopic Periodic Table, designed to explain isotopes as well as their importance. This resource incorporates mass spectroscopy data into each of the key ideas as well as provides multiple examples as to how varying isotopes are commonly used.
We’ve all seen and use the so-called Aufbau Diagram. It is a mnemonic used to remember the order of “filling” of atomic orbitals during the construction of the ground state electron configurations of the elements. The presentation of this diagram is largely disconnected from any physical meaning. Here’s what we tell our students: “Memorize the diagram, learn to use it, and you’re guaranteed to get the right answer.”
A complete understanding of why each element has a particular electronic configurations is a very complex subject. Even so, some confusion regarding the electronic configurations of the elements may be alleviated by looking at the physical properties of the electronic orbitals.
Are kids learning? Given the time it takes to implement and grade the activity, do I get a lot of "educational moments" out of it? Does it fit into the culture of the classroom? Is there a great deal of "conceptually rich" material in the activity that students can build on? I believe that two activities I tried this week fit the bill.
