9 Jun 2019

An improved method for drawing the bonding MO for dihydrogen

In-Class Activity

Submitted by Adam R. Johnson, Harvey Mudd College
Most of us have probably been there. Discussing homonuclear diatomic MO diagrams and on the first day you want to put up the sigma bonding molecular orbital for H2. If you teach it like me, you emphasize the LCAO-MO approach, so you draw a hydrogen atom with its 1s orbital interacting with a hydrogen atom with its 1s orbital...and then you notice giggling from the less mature audience members. My technique will help to prevent this from happening. The technique is in the "faculty only" files section.
Learning Goals: 

The instructor will draw the bonding MO of dihydrogen without accidentally causing laughter in the class or self embarassment.

Equipment needs: 

chalkboard or whiteboard

ability to adjust quickly just in case

Implementation Notes: 

I have come close to accidentally drawing the incorrect version of this diagram and I am able to stop myself quickly as illustrated in the instructions. 

Time Required: 
a minute to learn, a lifetime to master.
Evaluation Methods: 

When I do this correctly, the students don't accidentally see something which may make immature students giggle.

Evaluation Results: 

I have had multiple colleagues tell me that this technique worked for them and saved them from repeating an embarassing classroom event.

Creative Commons License: 
Creative Commons Licence


I've so totally been there. My solution has been to draw an H instead of a dot for the hydrogen nucleus. An H with a circle around it produces no giggles. However, Adam's approach shows that it doesn't have to be hydrogen.

Ha, thank you for this! So simple and yet it will make a big difference. 

I remember as a TA, a professor referred to the blue atoms in a crystal structure diagram as "balls" and had trouble recovering. Since then I am always very careful to call them "spheres."

I have made the blue spheres error myself in class. Luckily my back was to the class as I lost it.

I also asked the class yesterday if everyone had found their threesome. Er, I mean, group of three...

My father, Lee Johnson, chair emeritus of THE Ohio State Universiry molecular genetics department, at dinner, just informed me of an easier way to handle these orbs. Draw. It. Vertically. Mic drop.

The VIPEr community supports respectful and voluntary sharing. Click here for a description of our default Creative Commons license.