Our understanding of atomic structure developed as experimental evidence revealed the limitations of earlier models. Hydrogen played a particularly important role because its line emission spectrum could not be explained by classical models of the atom.
This interactive PhET simulation allows you to compare different models of the hydrogen atom and investigate how each attempts to explain the behaviour of the electron and the absorption and emission of light.
Compare the models rather than simply accepting the final one. Look at what each model predicts, test those predictions against the experimental observations and consider why increasingly sophisticated models of the atom were required.
Models of the Hydrogen Atom is provided by PhET Interactive Simulations, University of Colorado Boulder, and is used under the CC BY-NC 4.0 licence.
1. Begin with the experimental evidence
Observe what happens when light interacts with hydrogen. What is significant about the wavelengths of light that hydrogen absorbs or emits?
2. Examine the line spectrum
Hydrogen produces discrete spectral lines, rather than a continuous range of wavelengths. What does this suggest about the energies available to the electron?
3. Compare the atomic models
Explore the different models provided in the simulation. Which observations can each model explain, and where does it fail?
4. Investigate the Bohr model
In the Bohr model, the electron can occupy only certain allowed energy levels. What happens when the electron absorbs a photon with the correct energy?
5. Observe emission
Allow an excited electron to move to a lower energy level. What happens to the energy difference between the two levels?
6. Connect energy and wavelength
Compare transitions involving different energy changes. Which produce higher-energy photons? How does photon energy relate to wavelength?
7. Explore the Balmer series
Look for transitions that produce visible spectral lines. What do these transitions have in common? Relate what you observe to the Balmer series of hydrogen.
8. Beyond the Bohr model
Compare the Bohr representation with the more sophisticated quantum-mechanical model. Why should the familiar picture of an electron travelling around the nucleus in a fixed circular orbit not be regarded as a literal picture of an atom?
Keep asking:
How does the hydrogen line spectrum provide evidence that electrons can possess only particular energies?
The discrete spectral lines are experimental evidence for quantised electronic energy levels.