Spectral Lines & the Bohr Atom

Name: ________________________________ Section: __________ Date: __________

Station: __________ Group members: ________________________________________________

Goal: Use the Bohr model transitions to justify one spectroscopy claim with measured values.

Station card: Spectral Lines (8-10 minutes) Artifact: one completed transition table + one evidence-backed claim.

1. In Hydrogen mode, record these transitions:
   • H-alpha: $n=3 \to 2$
   • H-beta: $n=4 \to 2$
   • H-gamma: $n=5 \to 2$
2. For each transition, record wavelength $\lambda$ (nm), energy $E_\gamma$ (eV), and series name.
3. Switch to Lyman and record one transition. Note whether it is visible.
4. Switch to Inverse mode and enter $656\ \text{nm}$. Record the inferred transition and residual.
5. On the Hydrogen tab, use the Series Limit Microscope and move the probe toward high $n_{\rm upper}$. Describe the spacing trend.
6. Switch to Absorption mode and verify the same wavelengths appear as dark dips.
7. Move to Elements tab and run one Mystery Spectrum round (predict -> commit evidence -> check -> explain).
   • Explain how you used empirical line-pattern matching (not Bohr $n$-levels) to make your guess.
8. Write one sentence claim:
   • “Hydrogen lines are discrete because ____; evidence: ____.”
9. Explain the limit $n=\infty$ in your own words:
   • What does $E=0$ mean physically?
   • Why are bound-state energies negative?

Sanity checks

• For Balmer lines, increasing $n_{\rm upper}$ should push $\lambda$ toward the Balmer limit.
• Emission and absorption use the same wavelengths.
• Lyman lines should be in UV, not visible.
• $n=\infty$ is the ionization limit: the electron is unbound and the reference energy is $E=0$.