Here we have to get the reason for continues changing of the atomic model over the past 200 years.
The reason for changing the atomic model is-The results of further experimentation helped to revise and improve the model.
The development of atomic model occurred step-wise as given below-
1. Rutherford atomic model, which explained the result of electrical neutrality of atoms by discovering the nucleus of atom, but it cannot explain the stability of accelerated charge particle i.e. electron.
2. The concept of radiation was later explained by Planck's quantum theory.
3. After this Bohr introduce another concept of atomic model which can explain the stability of the electron and also a part of the spectrum of the atom, but it has the demerits on the fine structure of the atom and heavier elements.
4. Sommerfeld extended the Bohr's theory, which gave the light on the elliptical orbits of a certain orbit.
5. After this to explain the wave-particle duality of the electron, the wave mechanical concept was proposed by deBroglie's, which further extended to the uncertainty to localize the electron and its velocity at a time which is Heisenberg uncertainty principle.
6. Later the quantum mechanical approach to explain the atomic model Schrodinger proposed equation which effectively explain most of the phenomenon of the atoms.