Bohr's model explained the hydrogen spectrum by proposing that
- A. electrons can occupy any orbit
- B. electrons occupy fixed energy levels and emit a photon when moving to a lower one
- C. the nucleus emits light directly
- D. electrons spiral into the nucleus
Explanation
Restricting electrons to discrete levels means only certain energy differences are available, so only certain frequencies appear, which is exactly what a line spectrum shows. Classical physics predicted a continuous spectrum and an electron spiralling into the nucleus within a fraction of a second. The photon energy equals the difference between the two levels.