Spectra and particles
Emission & Absorption Spectroscopy
Explore how quantised electron energy levels produce line spectra. Switch between emission and absorption, identify unknown elements and calculate photon energy from wavelength.
Spectra and particles
Emission & Absorption Spectroscopy
Connect atomic line spectra, electron transitions and photon energy. Compare bright emission lines with dark absorption lines and use spectra as evidence, then link the approach to NMR as a complementary structure tool.
Controls
Emission spectrum
380–750 nmAbsorption spectrum
380–750 nmEnergy-level model
Selected evidence
- Element/source
- Hydrogen
- Line
- H-alpha
- Wavelength
- 656.3 nm
- Region
- visible
- Frequency
- 4.57e+14 Hz
- Photon energy
- 1.89 eV
- Transition
- n = 3 → 2
GCSE focus: each atom has different energy gaps, so each element produces a distinctive line pattern.
AQA A-level: hydrogen line spectra are evidence that electrons occupy discrete energy levels.
GCSE task
Compare emission and absorption. Why do the bright and dark lines occur at the same wavelengths?
A-level task
Use E = hc/λ for the selected line, then explain why shorter wavelength means a larger energy gap.
Teacher prompt
Ask: what would the spectrum look like if electrons could have any energy rather than fixed energy levels?
Educational spectra use approximate visible line positions and simplified relative intensities. They are for curriculum reasoning, not calibrated laboratory measurement.