While the Bohr model worked well for hydrogen, it could not explain more complex elements, and by 1919, Bohr was moving away from the idea that electrons orbited the nucleus, and he developed heuristics to describe them.
The Bohr model worked well for hydrogen. It could not explain more complex elements. Electrons orbited the nucleus. Bohr was moving away from the idea this. This was by 1919. He developed heuristics. This was by 1919. This was to describe them.