Question

How does quantum mechanics differ from classical mechanics?

Answer 1

Difference between Quantum and Classical mechanics:

Quantum Mechanics	Classical Mechanics
1. Matter can exhibit wave properties and waves can exhibit particle properties (wave-particle duality)	1. A wave can exhibit only wave properties, and a matter can exhibit only particle property.
2. Energy of a particle behaviour of a wave is equivalent to the product of a quanta of energy and its frequency, $E=h\nu$.	2. Energy of a classical wave is only dependent on its frequency and amplitude.
3. According to Heisenberg's uncertainty principle, a state cannot be prepared in which both the position and momentum of a particle cannot be determined simultaneously.	3. In classical mechanics both the position and momentum of a particle can be easily determined.
4. Quantum mechanics is applicable to microscopic.	4. Classical mechanics is applicable to macroscopic particles.
5. In quantum mechanics, there are only stages of energies in an atom.	5. In classical mechanics, the model of an atom contains a central nucleus, which is being revolved by electrons in different shells.