Are you teaching quantum numbers tomorrow and you need a refresher?
Great! I’ve got you covered.
The best part is I'm going to make this easier than you ever thought possible. Which means your students are going to cheering your name at the end of class and running home telling their parents what an awesome chemistry teacher you are.
Well, maybe not, but you might inspire a future chemist.
This is surprising, but you are going to start with the abbreviated electron configuration.
Abbreviated Electron Configuration
The first thing you need to have students do is write an abbreviated electron configuration.
For carbon, it will be [He] 2s2 2p2.
If you aren't sure about how to teach electron configuration, read this post.
Abbreviated Orbital Diagram
Then, you want to tell students to draw the abbreviated electron diagram for the valance electrons they wrote above. Have them draw one box under the 2s2 and 3 boxes under 2p2.
Next, they should fill the first box with a spin up arrow, then a spin down arrow.
The p subshell has 2 electrons. According to Hund's Rule, students must put in electrons spin up until each box has an electron, then put in electrons spin down. So, the first 2 p boxes will have a spin up arrow.
I know this seems like a lot of set up, but trust me it's 1000% worth it.
The Quantum Numbers
Now comes the easy part! As long as your students set everything up right from the previous steps, the quantum numbers will be as simple as pointing to the number and writing it down.
That sounds like homework your students will actually complete!
How to Find "n" for Carbon
For quantum number "n", have students look at the electron configuration. Ask them, "What was the last coefficient you wrote?"
(I often use the phrase “big number” so I don’t scare my students.)
Say to them, "That's right, it is that second big 2."
How to Find "l" for Carbon
For quantum number "l", have students look at the electron configuration.
Ask them, "What was the last subshell you wrote?"
(I often use the phrase “letter” so I don’t scare my students.)
Say to students. "That's right, p. And p is coded into 1."
For quantum number "ml", have students look at the boxes they drew earlier and look at the chart I have next to mine here.
In the chart, the first box is the -1 position. The second box is the 0 position. The third box is the 1 position. You can find the teaching chart handout for your students here.
Ask them, "You can clearly see which position the last electron went in at, right?"
They should say, "The 0 position."
For quantum number "ms", have students look at those boxes they drew earlier. Ask them, "Did the last electron go into the box spin up or spin down?"
Students should respond, "Spin up. So that is +1/2."
So the quantum numbers of carbon are 2, 1, 0, +1/2.
See? Isn't that easy? Read more about a fun demonstration for teaching quantum numbers here. (Spoiler Alert: All you need is a coffee mug!)
Quantum Charts Handout
Quantum Numbers Worksheet
Quantum Number Doodle Notes
Hi! I'm CoScine. I write chemistry worksheets for visual learners. They are fun, easy to follow, and most of them are quick to grade. Since I started my teaching career at the college level, these aren't just simple chemistry. These worksheets are hard core science made fun.