Question

Quantum mechanics says that there is no orbit present....electron cannot travel in fixed path,....Then what is this K,L,M, and N shells....?

Answer 1

That's a good remark. In fact these shells are just what is called in quantum mechanics 'states' depending on the quantum numbers n,l,m. So the electron has a just a probability to be in one of such states, in another word when chemists say that the electron is in sell K, this means that with a given probability (for example 1\2) the electron is in the state n =1. So just try to forget about orbits and say 'states'.

Best regards.
Hemza.