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.