Why? And how? Electrons has to move from one energy level to another?
The movement of electrons from one state to another is an observed phenomenon, so I'm not sure what you mean by "why do they have to?" They don't "have to", they just do, as a consequence of energy absorption. Physics is an attempt to understand why they do it. "have to" is metaphysics or philosophy.
Thanks for reply, I read electrons move from low energy level to high energy level by gaining electrons and vice versa,now my question is what is that energy level ?and what differentiates low from high energy ?
Not by gaining electrons, by absorbing photons.
The energy levels correspond to possible states of the (bound) electron - basically if you add energy (a photon) then the electron moves to a higher energy state.
I guess this may not be what you're after so maybe you want to clarify your question.
Lets think of it as a person who wants to watch a movie on the couch vs exercise in the gym. Couch is a low energy state and most people want to be there, If any external energy is given than a person might want to get out and exercise. Electrons are the same way, they want to be on the low energy state. It is just easier :)
Electrons get excited when photons turn up, otherwise like madphdstudent said, they prefer to slouch on the couch.
And usually some time after getiing all excited with the new photon, they get tired, get rid of it and back on the couch.
Until a really serious rent collector photon comes along and kicks them out entirely.
But in most of those cases they make a neutrino issue out of it, and they get accepted into a more hospitable community.
They only do that in their moments of weakness.
True, In the end it comes down to whether the nucleus is that bothered about it.,
Some of them would disintegrate,, because they just had enough of that.
Others would put up with it for a while.
when electrons are exiced they absorb energy so they jump to a higher orbit(shell), when they go into lower shells they release energy in the form of electromagnetic waves.
When a mentor like @phinds answers a question I recommend liking his reply to show your appreciation.
Thank you, but actually, I'm not a mentor ... more like the local wise-ass
ahaha that made me laugh friend.
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