Dual behavior of matter : de Broglie proposed that matter exhibits dual behavior i . e . matter shows both particle and wave nature . de Broglie ’ s relation is
Heisenberg ’ s uncertainty principle : It states that it is impossible to determine simultaneously , the exact position and exact momentum ( or velocity ) of an electron . The product of their uncertainties is always equal to or greater than h / 4π .
Heisenberg ’ s uncertainty principle rules out the existence of definite paths or trajectories of electrons and other similar particles
Failure of Bohr ’ s model :
a . It ignores the dual behavior of matter .
b . It contradicts Heisenberg ’ s uncertainty principle . is based on Newton ’ s laws of motion . It
Classical mechanics
successfully describes the motion of macroscopic particles but fails in the case of microscopic particles .
Reason : Classical mechanics ignores the concept of dual behavior of matter especially for sub-atomic particles and the Heisenberg ’ s uncertainty principle .
Quantum mechanics is a theoretical science that deals with the study of the motions of the microscopic objects that have both observable wave like and particle like properties .