atomic theory

Making Models to Build Knowledge

I needed a hands-on model that I could quickly assemble with articles found in the lab. A quick look through my cabinets yielded just such items: different colored marbles, an aluminum dish, and assorted other small items. But what about the electrons? Could I find something that could also help visualize the idea that the electrons are smaller and of much less weight than the protons/neutrons. Paper hole punches! Soon each table was equipped with the makings of an atomic model for every pair of students.

Almost immediately regret over the decision to select marbles settled in. The irritating sound of ricocheting marbles filled the classroom as students succumbed to the irresistible urge to repeatedly drop a marble from their hand onto the table allowing it to reverberate across the epoxy resin surface of the work space.  Clearly, there was no ill-will on the part of the students as they simply “needed” to handle those marbles. So, we carried on. Somehow students were simultaneously listening to instruction and were eager to assemble the atomic models as the theory was introduced. Dropping “neutrons” and “protons” into the “nucleus” was easy but they questioned how they should place the electrons outside the nucleus. Instinctively, they didn’t want to just drop their paper circles by the side of the dish. The concept of energy levels organically became part of our discussion and the students seemed relieved to have direction as to how to order their electron around the nucleus. Great care was taken to properly place their electrons.  Chatter about atoms was filling the classroom.

Later in the unit students easily built isotopes with this same model. They could visualize how the isotope carried the same charge and proton number as the “regular” atoms but that their mass was different. It was easy to accept that these isotopes, because of their varying masses, might have different physical properties and characteristics.

The same models were employed to make cations and anions by adding and removing electrons as the unit moved into ions. Students could easily visualize how charge became negative when electrons were added and positive when electrons were removed.

This same model provided variety to lessons, hands-on learning, and additional review as we built on the students’ understanding of the atomic theory. The models became a familiar tool in the classroom and as they sat before the students,  the marbles were heard ricocheting less and less across the tables. Just like with a beaker or graduated cylinder, the students began to handle the models as a simple piece of equipment required to accomplish a task, in this case, the task of mastering atomic theory.

Keep it simple! No fancy kits need to be ordered to provide our students with hands-on activities. Often things we have lying around can serve the purpose. The rewards include a buzzing classroom and student achievement.