Holiday molecules

Who doesn’t love the holidays? That time when interruptions to classes hit astronomical proportions, student learning momentum grinds to a halt and teachers search for something meaningful to do with their classes. Between the two extremes of slogging through thermodynamics when student retention is directly proportional to the length of time before the holiday, and showing a video lie some really fun hands-on activities that have the potential to foster lasting learning and help your students encourage enthusiasm about chemistry school-wide.

The holidays may be the time to ask yourself whether you have covered all the specific expectations from the Structures and Properties of Matter unit of the Ontario grade 12 University Preparation curriculum. Have your students described a Canadian contribution to atomic and molecular theory? If they have, then they will enjoy sharing a festive visualization of Ronald J. Gillespie’s work1 with the rest of the school. If you haven’t, then it’s time to recognize Gillespie’s influence on the grade 12 chemistry curriculum just as the Canadian government did in 2007 by awarding him the Order of Canada for his contributions to Chemical Education.

Ronald J. Gillespie, a chemistry professor at McMaster University from 1958 to 1989, and Ronald Nyholm, originally from Australia, met at University College in London, England and co-created VSEPR theory as a teaching tool in 1957. The symmetry in the first names of these two innovators is mirrored in the beauty of the Valence Shell Electron Pair Repulsion Theory, which reimagines Lewis dot diagrams to give grade 12 chemistry students a logical and plausible way of predicting the shape of molecular compounds.

This is the assignment I give students. You can make it formative or summative. In my courses, students write five-minute summative quizzes every class, and I make this activity equivalent in value to that of a quiz.


Contribute to Chemistry Education by making and displaying a creative VSEPR model.

Individual Task

You will be assigned a molecule and given a blank paper rectangle, which will become your molecule’s tag. On the tag, clearly and neatly (use a ruler where appropriate) draw the Lewis diagram, identify the shape, bonding angles and formal charge on one side of the sheet and diagram on the other side.

Submit the diagram to your teacher (this should be completed in the first 10 minutes of class). After your teacher has evaluated the diagram, you will attach the tag to your molecule before hanging it.

Once your molecule is approved by your teacher, construct a creative 3-D VSEPR model of your molecule to celebrate the season using the materials available (Polystyrene spheres, skewers, string, pipe-cleaner, paint, pom-poms — we get a myriad of materials from the dollar store). Be as accurate as possible with angles and representation of lone pairs. Attach the label of your molecule (describe above). Hang your molecule in the hallway.

There is an additional rubric for communication (out of 4), evaluating the accuracy of the bond angles, the quality of construction, the creativity of the correct molecular representation and the cohesiveness of the teamwork involved in constructing the model.

The Advanced Placement program has moved towards a particulate conceptualization of chemistry, which this has forced me to reconfigure how I teach the fundamental concepts in the grade 11 course. Having students construct VSEPR models in grade 12 reinforces student understanding of the shape of molecules at the atomic level. It is a fun and lasting commemoration of their grade 12 chemistry experience. To facilitate hanging the molecules, I had several pairs of hooks placed across from each other in the hallway a week before the activity. The growing number of holiday VSEPR molecule chains across the hallways at our high school are a visual missive to future chemistry students that molecules come in different shapes (albeit very small sizes). The pictures on the following page capture the creative molecules hung in our hallways. They provide a great opportunity to evaluate students through conversations and observations, as required by Growing Success2… and they are a lot of fun, not to mention that it gives me the opportunity to tell students that Prof. Gillespie wrote my first year chemistry textbook and delivered a quarter of the lectures in my first year chemistry course.

Notes and references

  1. McMaster Chemical Extracts, Ronald Gillespie: A Lifetime in Chemistry, volume 2, 1999., retrieved 11/01/2013
  2. Growing Success: Assessment, Evaluation and Reporting in Ontario's Schools, First Edition Covering Grades 1 to 12

A hallway of holiday molecules at University of Toronto Schools

Handmade molecule shapes hung on suspended line in school hallway.Students standing underneath handmade molecules in school hallway.

(Note: credit for the original conceptualization of this activity is rightfully given to my wonderful colleague Suzanne Monir)