The Bohr model seemed to work pretty well for atoms with only one electron. But apart from hydrogen, all other atoms in the periodic table have more, some many more, electrons orbiting their nuclei.

Whenever an electron changes speed or direction (according to the Bohr model), it emits radiation in the specific frequencies associated with particular orbitals.

Bohr’s Model of an Atom: Students get to know the Bohr’s Model of an Atom. Find out what are its limitations and the postulates it is based on.

Just as the Bohr model failed to reproduce the hydrogen atom's energy levels properly, so did the Schrödinger equation. It was quickly discovered that there were three reasons for this.

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.

The result was the Bohr model of the atom ... is bathed in a laser beam with a frequency exactly tuned to the energy difference between two of its electron levels - call them 1 and 2.

But instead of solving the Bohr-model problem, Hagen applied the “variational principle” – a technique usually reserved for approximating quantum-mechanical systems that cannot be solved analytically ...