Question

The Bohr model was important, even though it ultimately didn't work out for multi-electron atoms. What was the fundamental idea in the Bohr model that is still true in the quantum mechanical model? 

Answer 1

The Bohr Model is a planetary model in which the negatively charged electrons orbit a small, positively charged nucleus similar to the planets orbiting the sun (except that the orbits are not planar). The gravitational force of the solar system is mathematically similar to the Coulomb (electrical) force between the positively charged nucleus and the negatively charged electrons.

Main Points of the Bohr Model

• Electrons orbit the nucleus in orbits that have a set size and energy.
• The energy of the orbit is related to its size. The lowest energy is found in the smallest orbit.
• Radiation is absorbed or emitted when an electron moves from one orbit to another.

The main problem with Bohr's model was that it works very well for atoms with only one electron, like H or He+, but not at all for multi-electron atomic systems. Bohr's model allows classical behavior of an electron ( i.e., orbiting the nucleus at discrete distances from the nucleus)

In the Bohr Model, the electron is treated as a particle in fixed orbits around the nucleus. In the Quantum Mechanical Model, the electron is treated mathematically as a wave. The electron has properties of both particles and waves. Thus, this fundamental idea of Bohr model is still valid in quantum mechanical model.