April 2017

# Sorting the atomic model

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Sharon Geyer, Woodstock Academy, Woodstock CT

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I am a big fan of sorting activities to help my students learn new concepts. I have created several “card games”1 for nomenclature, identifying chemical and physical changes and properties. These sorting games help students learn new concepts or practice difficult skills, like naming acids. The article “Learning By Sorting” by Michael Lovrencic and Laurie Vena in The Science Teacher, February, 2014 gives a nice explanation of the technique.

This year I decided to add a sorting activity for the development of the atomic model to my repertoire. The traditional atomic model lesson boils down to a vocabulary-heavy history lesson. Even with a cathode ray tube demonstration and a PhEt simulation2 of the gold foil experiment, it is hard for students to understand the important points of the story. In an effort to make this lesson more student-centered, I've moved the content delivery portion to a homework video the night before they do the sorting activity. In class, I placed pictures of the five atomic models around the room. Each student received a set of two or three cards with terms, phrases or names that relate to one of the models. The first challenge was for each student to identify the model that fit their set of cards. Once the students have gathered around the model, they then worked in a group to sort his or her cards and generate an explanation of the words, phrases and names on the cards for their model. Groups had about fifteen minutes to discuss their model and plan for their presentation. Each group explained their atomic model to the whole class, starting with Dalton and working in chronological order through the plum pudding model, the nuclear model, the Bohr model and finally the quantum model. After the presentations,
I showed the kids the cathode ray tube and then we worked with the Rutherford Scattering PhET simulation.3

The final event of the day was an overview where each group had a full set of the atomic model cards to sort. Although they knew the ones from their presentation, they needed this chance to think through the other important discoveries and scientists associated with the whole picture. I was pleased with the outcome of this sorting lesson: shifting the learning into my students’ hands with the card sorting and the class presentation. The more interactive lesson made the atomic model more accessible to students. The small group activity generated thoughtful discussions as they tried to piece together the facts and explain the experiments that led to new discoveries.

Dalton's atomic model didn't really come with a picture of the atom; I had to ad-lib a little.

Discussing plum pudding model

It's hard for kids to believe that the plum pudding model was the best explanation at that point in history.

The nuclear atom model was a result of the gold foil experiment.

Presenting the Bohr model.

The quantum model of the atom proved difficult to draw.

## Notes

1. Contact Chem 13 News, chem13news@uwaterloo.ca for a copy of my sorting cards.
2. Interactive Simulations project at the University of Colorado Boulder creates free, interactive math and science simulations. https://phet.colorado.edu/
3. https://phet.colorado.edu/eu/simulation/rutherford-scattering

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