Make electron configurations the anchor of the light and electron unit
My light and electrons chapter used to feel like I was an old man sitting on a bench telling a wandering story to the squirrels that had about 12 “and then” statements in the middle.
Valence electrons. And then the shape of the periodic table. And then Aufbau diagrams. And then quantum numbers. And then Lewis dot structures. And then flame tests…
All of these concepts pull directly or indirectly from electron configurations. This year in my grade-level and honors chemistry classes I made a concerted effort to make electron configurations be the central anchor point for all of these other concepts. And the kids did great! Having the anchor (and applying the anchor) of electron configuration helped the students take the unit, which can feel a little disjointed, and make it much more cohesive. Here are some key thoughts for uniting the light and electrons unit.
Start with electron configurations.
After a brief history lesson from Democritus and Leucippus up to Schroedinger, we discussed orbitals and the electron cloud. And then I dove straight into electron configurations. We start closest to the nucleus and work our way outward.
I use a simple little phrase to help them know what the numbers and letters in the electron configuration mean. Energy level, block (or subshell), how many electrons. Over and over. This repetition seems to help them recognize that we are describing how every single electron in the atom is moving.
It sounds like this, “In the first energy level in an s shaped orbital there are two electrons. In the second energy level in an s shaped orbital there are two electrons. In the second energy level in p shaped orbitals there are four electrons.” That must be oxygen.
How to teach electron configurations with the periodic table
I teach my students to get electron configurations straight from the periodic table by reading top to bottom and left to right. Every time we fill a subshell, write it down.
At the beginning of the unit, I make them write the complete electron configuration starting with 1s2 every time. It doesn’t take too long before they feel the repetition and stare in horror at the bottom of the periodic table hoping that they don’t have to account for 118 electrons. Pretty soon, a kid (usually someone with a name like Dave) will ask if they really have to write them all down or if they could just write the last thing.
I make a big production about how Dave wants to shortcut the whole system because it is so much work. I talk about why we can’t just identify the very last electrons in the atom because it ignores other electrons that are important. And then I make a “compromise”. I show them how to bracket the previous noble gas. We all cheer for Dave. He saved us some work. What a guy.
Always circle the valence electrons.
This is something that I just tried this year and it was great. The students know that valence electrons are the most important for determining reactivity.
In our class we say, “Electrons are shallow, they only care about what’s on the outside.”
This year, I started having the students identify and circle the valence electrons in their electron configurations. This forced them to recognize that not all electrons are valence. Only the highest energy level. This also helped them to see the connection between s and p orbitals and how they add up to eight electrons. It connected to the representative columns on the periodic table. There were many lightbulbs that went on just by circling valence electrons.
Connect Aufbau, Hund, quantum numbers and Lewis to electron configurations
I won’t go into depth here, but all of these concepts are tied back to electron configurations.
An Aufbau diagram is the picture book version of an electron configuration.
Hund’s rule just dictates how the electrons will fill up their electron configurations in space.
Quantum numbers are an address system to identify how each of the electrons in an electron configuration could be identified.
Lewis dot structures are a shorthand way to represent the valence electrons that we have been circling all chapter.
Having the unifying factor of the electron configuration makes the light and electron chapter much more cohesive. The students have an anchor to return to. It gives them some problem solving skills when they get stuck. Basically, it makes me sound less like an old man rambling on and on sitting on the park bench. Now I am just an old man. Not rambling.
Metalworks: Where Stoichiometry Is Forged is coming very soon! I just received the first round of graphic design and it looks amazing.
Imagine six students playing a fast-paced game where it is always their turn. They collect dimensional analysis cards to convert from metal ores to pure metal. Every time they complete a stoichiometric conversion, they make money! This game is used as a manipulative first and then, as their skills grow, becomes a reinforcing game. Check it out today and click “Notify When Available” to be the first one to know about the preorder sale. Coming fall of 2026!
Comments