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We have developed a tabletop game to help students get comfortable with symmetry adapted linear combinations of orbitals (SALCs), a conceptual model used to understand bonding in molecular orbital theory. We have found that students often get anxious about SALCs and miss not only the visual connections to symmetry, but also the fun! This LO includes information about the game, files you can use to print your own copy as well as a link in case you want to purchase a copy, and an example of how it might be incorporated into the classroom.
Information about the game: SALC is an orbital arrangement game aimed at helping inorganic chemistry students visualize and depict SALCs. During a turn, one student positions ligand orbitals around a metal center orbital and their classmates place blind bets for correct or incorrect SALC arrangement. At the end of the game, the winner is the student whose bets have won them the most points. 3 to 6 students can play with a single set. In this version of the game, s, p, and d orbitals on the central (metal) atom are considered while only s orbitals are considered for the surrounding ligands. Thus, the students are specifically representing sigma SALCs. The cards specify the point group, the orbital, and the Mulliken symbol, as well as whether the student should build a bonding or antibonding SALC. There are cards in the deck in the C2v, C3v, C4v, D3h, D4h, and Oh point groups.
| Attachment | Size |
|---|---|
| PDF of the rulebook for the game | 1.15 MB |
| PDF of the game pieces, which can be used to print and cut everything out | 793.11 KB |
By playing and engaging in the SALC game, a student will
- practice combining ligand (s) orbitals to form SALCs that match a specific central (metal) atom orbital in a specific point group
- practice constructing SALCs by inspection and visualization (rather than using the projection operator)
- distinguish between bonding, non-bonding, and antibonding interactions between a contributing ligand (s) orbital and a specific central (metal) atom orbital in a specific point group
- appraise ligand (s) orbital combinations constructed by classmates to determine accuracy of the SALCs
- feel less intimidated by SALCs because they can be put together in a game
A printed copy of the game and all its pieces.
There are many potential ways to implement SALC in a classroom and I hope that anyone who uses it will share their experiences in the comments section.
I used this activity in my undergraduate Inorganic Chemistry class which has primarily Juniors and Seniors, which is taught 3 days a week for 50 minutes. Each week we have one day completely devoted to group work and SALC: An Orbital Arrangement Game was used on one such Wednesday. This experience benefited from the students working with their usual groups so that they already knew a lot about working together. Prior to playing the game, students had heard about SALCs through a lecture video and an in-class lecture/discussions. They had also been given recommended reading on the topic.
I gave each group of 4 students the following game components: a set of betting chips, two scoring mats, a set of 6 ligand orbital pieces, and a set of 8 playing cards. I had separated the bonding (normal) and antibonding cards and gave the groups bonding cards to start with. Non-bonding examples are in both sets, which is something I made a particular point of mentioning when I reviewed how to play the game at the start of the class. I posted the pdf of the game’s rulebook to our Canvas course about a week before we played the game, but I also went through the salient points and did an example on the board at the start of the class period. When groups got through their 8 cards, they could choose to play it over or get a new set and they could choose bonding or antibonding. Groups chose to approach the game in various ways: some were very competitive and some were extremely cooperative. I let each group do their own thing and moved around the room to field any questions that arose or watch some of the gameplay.
Evaluation
Students in the class received credit for playing the game and for turning in “a brief (1-2 paragraphs) reflection on your experience with the game. You can include pictures if you think they would be helpful in explaining your perspective. What ideas/topics/questions did playing the game bring up for you? What tactics did you employ that were most successful?”
SALCs were tested in various ways throughout the rest of the semester, though no one was directly tested on the game play and I opted not to give extra credit for winning as I assumed that bragging rights were enough bonus.
In their reflections and my end of course survey students generally indicated that they found the game helped with their visualization of SALCs and made the topic more approachable. That said, they all knew that I helped design the game, so this was not unbiased. Still, I was very glad to hear the students say that their confidence was boosted and that they had fun!
I made the pieces of the game available to students throughout the rest of the semester in case they wanted to play again or just use it for at-home practice. Though only a couple of students took me up on this offer, they said it was helpful.
Some of the most common points of confusion were as follows. Students needed to be reminded that the cards included different point groups and that the maximum number of ligand orbitals involved in the SALC was equal to the number of ligands around the metal in that point group. Students also had to practice considering where the central (metal) orbital and the ligand orbitals would be in 3 dimensional space even though the card could only show it in 2 dimensions. Since these are common questions that arise when teaching SALCs in a more traditional setting, I was glad to see that the game also brought these questions to the forefront. The game only covers sigma SALCs, which could be considered a limitation, but I think it would have been overly complicated if pi SALCs were added to the mix.