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.
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.
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.
Last year while attending the Biennial Conference on Chemical Education at GVSU I had the opportunity to hear a talk that showed a video of a chemical demonstration showing the burning of magnesium metal. We have all seen many of these videos (thank you YouTube) and probably have performed this demo for our own students many times. During the video it may have been represented with a chemical equation followed by the students being asked to balance the equation or maybe even predict the products. Although the use of video including the showing of the equation nicely represents the macroscopic and symbolic representation, what was so unique about this particular video is that it also included the particulate representation embedded on top of the video of the demo. This was the first time I had seen the particulate level representation done like that and so I was intrigued in wanting to find more of these representations.
I have my students use Orbital Viewer when learning about quantum numbers and their associated rules, electronic orbitals, and other quantum concepts. I have developed a worksheet that allows students to use Orbital Viewer to explore various concepts related to electronic orbitals.
Orbital Viewer is a fantastic program for displaying electronic orbitals. It is a great resource for teaching students about orbital shapes and the rules, nomenclature and notation of the quantum numbers n, l and m.
