The simple Bohr model cannot be directly applied to calculate the energy levels of an atom with many electrons. This is because:
 

1. of the electrons not being subjected to a central force.
2. of the electrons colliding with each other.
3. of screening effects.
4. the force between the nucleus and an electron will no longer be given by Coulomb's law.


 

(a) Hint: In multi-electron atoms, there will also be repulsion due to other electrons.
The simple Bohr model cannot be directly applied to calculate the energy levels of an atom with many electrons. This is because of the electrons not being subject to a central force.