Physics 30 pHet Lab: Atomic Models
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Name: ______________________________
Scientists make observations of the world around them. Based on those observations, they often develop
models of the phenomena they observe. In this activity, you will:
a) develop characteristics of a model for the hydrogen atom.
b) test different models, comparing them to other models and your observations.
c) examine and extend your understanding of the wave-particle duality
Go to http://phet.colorado.edu/en/simulation/hydrogen-atom. Click “Run Now”.
1. Define a photon. Is the photon a particle or a wave?
2. Make sure the dial is set on “Experiment” and the Light Control set on “White”.
a. The gun is used to shoot light photons (energy bundles). Each circle from the gun represents a photon
corresponding to that color (with fuzzy purple representing UV).
b. The box with a question mark represents a hydrogen atom.
c. Predict what will happen to the photons as they pass through the hydrogen atom. Be sure you address
what will happen to the different colors. Give a justification for your prediction.
3. Push the red “O” button on the gun and write down your observations of what happens as the photons
pass through the box. Be specific, covering everything you observe. What do you think is making the
photons deflect? Is every colour deflected? Do your observations match your prediction? Explain.
4. Change the light control from “white” to “monochromatic”. Are photons still being deflected?
Physics 30 pHet Lab: Atomic Models
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5. Change the colours of the photons by moving the handle up and down the spectrum. Record your
observations in the chart below:
Colour
Observations
UV
Purple
Green
Student’s
Choice
____________
6. Return the light control to “monochromatic” light, and click the “show spectrometer” box. What is the
spectrometer box keeping track of?
7. What conclusions can you make about the structure of the hydrogen atom? Your conclusion should
address as many of your observations as possible.
8. Once you have made your conclusions, use them to formulate a model of the hydrogen atom. Based on
what you observed, what characteristics must the hydrogen atom possess? Justify each component by
addressing which of the above observations this characteristic addresses. For example, if no photons
passed through the box, then you would infer that the hydrogen atom must have a rigid wall around it.
Physics 30 pHet Lab: Atomic Models
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9. Now move the switch in the upper left corner to “Prediction”. The simulation gives you six possible models
of the hydrogen atom. Fire the gun at each of the models. What observations can you make about the
photons and/or the hydrogen atom? For each model, alternate between white light and light with a
wavelength of 97 nm.
Specific
atomic model
tested
Billiard Ball
Observations
How do these observations
support the experimental
results in the first part?
How do these observations
contradict the experimental
results in the first part?
Plum Pudding
Classical Solar
System
Bohr
De Broglie
Schrodinger
10. Does one or more of the above models match the results of the experiment in the first part of this activity?
Which ones? Explain.
Physics 30 pHet Lab: Atomic Models
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11. Based on your observations in the first part of the experiment, are any of the above models highly unlikely
to match the actual hydrogen atom? Which one(s)? Why?
12. What can you definitely conclude about the make-up of the hydrogen atom based on this simulation?
13. With the Bohr model selected, click the “Show electron energy level diagram”. Using the electron energy
level diagram and the spectrometer, describe what is happening to hydrogen’s one electron.
14. In the help menu, click on transitions. Enter the first five wavelengths into the wavelengths box and
observe what happens to the electron. Does this support your statement in number 12? If not, adjust your
statement to explain the behaviour of the electron.
15. Now enter wavelengths that are not listed. What do you observe? Does this support your statement in
number 12? If not, adjust your statement to explain the new behavior of the electron.
Physics 30 pHet Lab: Atomic Models
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16. Now go to http://phet.colorado.edu/en/simulation/quantum-wave-interference. Click “Run Now”. In the right-hand
side menu, click on “Double Slits”. In this simulation, you can experiment by sending four different “streams” through
the double-slits. Use the table below to record your hypotheses and observations.
Particle
Hypothesis (what you think will
happen when it passes through the
double-slits)
Observation (what you observe
happening when it passes through the
double-slits)
Photons (feel free to try a variety of
colours)
Electrons
Neutrons
Protons
17. Write a paragraph about your observations from this simulation. Include elements that aligned with your hypotheses,
anything that may have surprised you, and draw connections to what you have learned previously, where
appropriate.