Why did the Bohr model successfully explain hydrogen’s spectral lines?

The Bohr model successfully explained the spectral lines of hydrogen by incorporating quantum theory into the description of atomic structure, departing from classical physics.12

Key reasons for its success include:

• Discrete Orbits: Niels Bohr proposed that electrons are restricted to specific, allowed circular orbits with discrete radii and energy levels, rather than orbiting at arbitrary distances.13
• Energy Transitions: He asserted that light is emitted or absorbed only when an electron makes an abrupt transition—a "quantum leap"—between these stationary states.134
• Conservation of Energy: The energy lost or gained by the electron during these transitions is exactly equal to the energy of the emitted or absorbed photon. This relationship matches the discrete wavelengths observed in hydrogen's emission spectrum.514

While the model provided a numerical match for hydrogen's energy levels, it is now considered a simplified, historically significant step, as it failed to generalize to atoms with more than one electron.23