Atoms and Light

Energy levels and spectra

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Electrons in atoms have discrete energy levels. For hydrogen, $E_n = -13.6/n^2$ eV.
• Jumps between levels emit or absorb photons with exactly the energy difference.
• Every element has a unique spectral fingerprint.

Steps

1. Neon signs
2. Energy levels
3. Hydrogen’s red line
4. Counting lines
5. Dark lines in sunlight
6. Ionize it