When describing abstract concepts like chemical bonding, it always seems to feel far too easy for both teachers and students to resort to the “wants” and “needs” of atoms. After all, we understand what it means to want, need, or like something, so it often feels appropriate (and easier) to use a relatable metaphor or subtly anthropomorphize these atoms to accommodate our students’ current reasoning abilities. While predicting the types of bonds that will form and the general idea behind how atoms bond can be answered correctly using such relatable phrases or ideas, the elephant in the room still in remains—do our students really understand why these atoms bond?
Science Practice: Developing and Using Models
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.
Whether you are introducing collision theory or something more demanding like reaction order, the reaction between sodium thiosulfate—Na2S2O3 and hydrochloric acid can provide a consistent, accurate, and engaging opportunity for investigating these topics.
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.
In this blog post, I'll discuss how I've expanded my use of model kits within my chemistry class to help explore a variety of topics with my students.
Here is what I told my students as we were studying gas laws. I have a bag of potato chips at see level and then I go to Denver where the pressure is less? What happens? Draw and build a model on your whiteboard.
A quick search on Amazon for a package of 144 ping pong balls and a trip to the arts and crafts store for paint, magnets, and glue and I was ready to start making my own class set of model kits.
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.
If you look at any chemistry textbook, you will see Lewis structures introduced long before electronic and molecular geometries. This makes sense since you need Lewis structures to determine molecular geometry. Unfortunately, research has shown that students often do not recognize that the purpose of drawing Lewis structures is not to create the structure itself but to use it as tool to understand the properties of the molecule (Cooper, Grove, Underwood & Klymkowsky, 2010).
This past summer our conversations turned to, “How can we improve our instruction to try and prevent the initial misunderstanding?” We had all read Dorothy Gabel’s article Improving Teaching and Learning Through Chemistry Education Research: A Look to the Future. We were intrigued by the author's description of the three fold system of representing concepts in chemistry.