Introduction
You have no doubt been exposed many times to the Bohr model of the atom. You may have even learned of the connection between this model and bright line spectra emitted by excited gases. In this experiment, you will take a closer look at the relationship between the observed wavelengths in the hydrogen spectrum and the energies involved when electrons undergo transitions between energy levels.
Objectives
In this experiment, you will
- Use a spectrometer to determine the wavelengths of the emission lines in the visible spectrum of excited hydrogen gas.
- Determine the energies of the photons corresponding to each of these wavelengths.
- Use a modified version of Balmer’s equation to relate the photons’ energies to specific transitions between energy levels.
- Use your data and the values for the electron transitions to determine a value for Rydberg’s constant for hydrogen.
Sensors and Equipment
This experiment features the following sensors and equipment. Additional equipment may be required.
Correlations
Teaching to an educational standard? This experiment supports the standards below.
- International Baccalaureate (IB) 2025/Chemistry
- Structure 1.3.2—The line emission spectrum of hydrogen provides evidence for the existence of electrons in discrete energy levels, which converge at higher energies.
- International Baccalaureate (IB) 2025/Physics
- The students should understand hat emission and absorption spectra provide evidence for discrete atomic energy levels
- The students should understand that photons are emitted and absorbed during atomic transitions
- The students should understand that the frequency of the photon released during an atomic transition depends on the difference in energy level as given by E = hƒ
- The students should understand that emission and absorption spectra provide information on the chemical composition.
- The students should understand the discrete energy levels in the Bohr model for hydrogen as given by E = − (13.6/n2) eV
Ready to Experiment?
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Purchase the Lab Book
This experiment is #21 of Advanced Physics with Vernier — Beyond Mechanics. The experiment in the book includes student instructions as well as instructor information for set up, helpful hints, and sample graphs and data.
