Sunday, March 13, 2011

AP Physics B:
Exploring Models of the Hydrogen Atom

Learning Objectives
• Explain qualitatively the origin of emission or absorption spectra of gases

Assessment Type
This activity can be used to introduce atomic models and serve as a formative assessment of students' understanding of alternate models of the Hydrogen atom.

Assignment Details
  1. Direct students to the "Models of the Hydrogen Atom" simulation from PhET.
  2. Click "Run Now" to begin the simulation.
  3. Ask students to explore the various atomic models under the prediction setting, trying to decipher what distinctions can be made between the models.
  4. Students, working in pairs, should examine at least three atomic models in detail (Bohr's model and two others of the students' choosing). Student pairs are asked to discuss the models and create a two-to-three sentence description for each of their three models explaining how the model can be employed to explain the emission of light.
  5. Ask students to turn on the spectrometer and collect spectral data for each of their three atomic models.
  6. Students should then compare the spectra from the three models, and record at least one similarity and/or difference between each pair of models that they observed.
  7. Turning the dial to "Experiment," students can collect spectral data on a 'real' Hydrogen atom.
  8. After sufficient data is collected, the students will compare the experimental data to the predictions of their three models and rank them from most accurate to least accurate.

Instructor's Notes
  • Use the slider at the bottom of the simulation to make time go faster, making it possible to collect data more quickly.
  • Encourage students to use the camera button on the spectrometer to record their spectral data sets.
  • Ask students to speculate why the spectra from each model differ in the ways they do.
  • A particularly worthwhile discussion could be focused on the relative merits of the Bohr and deBroglie models.

Students can be assessed on the following criteria.
6 pts - Students provide accurate two-to-three sentence descriptions for each of their three atomic models.
3 pts - Students correctly describe at least one similarity and/or difference between each pair of models they observed.
1 pt - Students properly rank their three models in order of accuracy.

Total = 10 pts