Why was a change in the Bohr Model of atom required ? Due to which important development (s), concept of movement of an electron in an orbit was replaced by, the concept of probability of finding electron in an orbital ? What is the name given to the changed model of atom ?

Explanation

In Bohr model, an electron is regarded as a charged particle moving in well defined circular orbits about the nucleus. An orbit can completely be defined only if both the position and the velocity of the electron are known exactly at the same time. This is not possible according to the Heisenberg uncertainty principle. Further more, the wave character of the electron is not considered in Bohr model. Therefore, concept of movement of an electron in an orbit was replaced by the concept of probability of finding electron in an orbital due to de-Broglie concept of dual nature of electron and Heisenberg.s uncertainty principle. The changed model is called quantum mechanical model of the atom