12/26/2023 0 Comments Ion bonding videoIn short, the majority of my students couldn’t accurately represent the attractive/repulsive forces present in the diagram. Scenario 2: Using your understanding of attraction, provide an explanation for why phosphorus (P) and chlorine (Cl) form a covalent bond instead of an ionic bond. Scenario 1: If atom X has an electronegativity of 3.6 and atom Z has an electronegativity of 1.2, draw vectors to represent the attractive and repulsive forces present between the atoms. To satisfy this uncomfortable feeling, I proposed to them the following two scenarios that I knew couldn’t be correctly answered unless they understood what was going on at a conceptual level. Statements like this bothered me because they didn’t convince me that the student actually knew what was taking place. For example, they might say that because fluorine’s electronegativity is so much larger than sodium’s, fluorine will end up taking sodium’s valence electron. It became obvious to me that many of them had just simply memorized the consequence of what would happen if one atom had a significantly larger electronegativity than another. However, I started to notice this whole idea of electronegativity difference wasn’t sitting so well with a significant portion of my students. Much of this new approach was centered on a topic we had recently learned-electronegativity. So for the first time ever in my career, I decided to pump the brakes on the wants and needs of atoms and instead focus more on the electrostatic interactions between atoms to account for chemical bonding. It wasn’t until a colleague of mine shared a great JChemEd article, 1 which focused on placing a greater emphasis on the electrostatic interactions in chemical bonding, that I started to really question the depth of understanding on this topic that I was expecting from my students. I was taught that way, I taught it that way, my students learned it that way from me, and my students explained it that way to me for years. I don’t know about you but that feels awfully familiar to me and it’s not too difficult to realize why. “Since chlorine wants 1 electron and sodium wants to lose 1 electron, chlorine will steal sodium’s 1 valence electron so that they both have a full outer shell and are stable.” The following explanation should feel rather familiar. 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 remains-do our students really understand why these atoms bond?
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