But there was good evidence he was right: the electrons in his model lined up with the regular patterns (spectral series) of light emitted by real hydrogen atoms. Bohr's theory that electrons ...

Bohr proposed adding to the model the new idea of quanta put forth by Max Planck in 1901. That way, electrons existed at set levels of energy, that is, at fixed distances from the nucleus.

Chapter 12: Atoms Question 1: Explain Rutherford’s model of the atom and its limitations. Question 2: Derive the expression for the radius of the nth orbit of the hydrogen atom using Bohr’s model.