What is Quantum jump of an electron? Can any one define quantum jump 9 quantities jump of an electron ? 
I know it it is a silly question but can anyone please explain me in detail.I am a  learning about the structure of atom  and I want some help. 
Can anyone help. 
 A: Electron's quantum jump is the same thing as an atomic electron transition.

https://en.wikipedia.org/wiki/Atomic_electron_transition

At the beginning, the electron has one energy and sits at some level which may be represented by some "typical distance" from the nucleus. 
At the end, it has another value of the energy, so a different "typical distance from the nucleus".
Quantum mechanics, the theory of atoms etc., implies that not all values of energy but only some particular values are allowed. This is why the electron can't gradually slowly walk or creep from one energy (or one orbit) to another. It has to "jump" i.e. omit all the values in between. It directly changes from one level of energy to another, i.e. by absurbing a photon to obey the energy conservation law.
Energy jumps are behind the emission and absorption of light by atoms.
To learn everything about the jumps and why the energy levels are discrete etc., one needs to learn quantum mechanics.
A: (add my comment as an answer)
It all depends on the time-energy uncertainty relation 
$$ (\Delta t) (\Delta E) \ge ℏ/2 $$
(see for example here and here).
Classicaly a particle can access only system (energy) states which are compatible with its (current) energy. Actually this is still true in quantum mechanics, the difference is the time-energy uncertainty which provides a twist if you like.
A particle can transition to another (energy) state by a change of its energy. Due to the uncertainty relation, given a (small) time-frame, some energy can be given so to say, to the particle, so the jump to another state (which was classicaly unlikely) is now possible and can happen. Of course this works both ways.
