Why do shells further from the nucleus have higher energy than those closer?

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Lukedavidhopkins1
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#1
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It really confuses me and I can't find an explanation for it. And how does it help explain why electrons are attracted to the nucleus but not drawn into it?
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Plato's Trousers
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(Original post by Lukedavidhopkins1)
It really confuses me and I can't find an explanation for it. And how does it help explain why electrons are attracted to the nucleus but not drawn into it?
Basically, you can think of the nucleus as sitting at the bottom of a potential energy well. Because the electron and nucleus have opposite charge, the force is attractive, meaning that for an electron to exist away from the nucleus it needs to "climb up" the potential energy well. The further away from the nucleus, the more energy it must have. If an electron gains energy (say by absorbing a photon) it can climb up further (ie more distance away). Conversely, if it drops back down the energy well (ie moves closer to the nucelus) it gives out energy (as a photon).

However, the energy well is actually quantised, not continuous. The electron can only take certain values of energy. Those values are determined by solutions of the Schrodinger equation and are defined by the quantum numbers of that electron (n, m, l and s). Each combination of quantum numbers give rise to a particular "orbital" (e.g. the 5d orbital has n=5, m=2, l=+2 through -2, and s=+1/2 and -1/2).
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math-friend
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#3
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Actually we don't call energy shells any more but energy levels as it is hard to locate the electrons' exact location in each level.

Now the the lowest the energy most stable the atom is. Therefore the energy levels closest to the nucleus are filled first to keep the energy of the atom lowest to achieve most stable state.
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math-friend
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Electrons can't collapse into nucleus because they stay in energy levels of certain fixed energy and they don't lose or gain energy as long as they are in it. It is only the time they gain or loose some energy when they jump from one level to another.
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Lukedavidhopkins1
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Thanks
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math-friend
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To gain height stability the the first electron goes to the closest energy level which has lowest energy because of the electrostatic forces between the nucleus and electrons in it. Once the first level is full (only two electron) then the next available level with lowest energy (again closest to opposite charged nucleus) is the second energy level and so on.
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Lukedavidhopkins1
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(Original post by math-friend)
To gain height stability the the first electron goes to the closest energy level which has lowest energy because of the electrostatic forces between the nucleus and electrons in it. Once the first level is full (only two electron) then the next available level with lowest energy (again closest to opposite charged nucleus) is the second energy level and so on.
What's height stability?
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DODOYKUSGAN
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Thank you so muuuuch. Now I can explain it to my students.
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Tootles
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#9
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(Original post by DODOYKUSGAN)
Thank you so muuuuch. Now I can explain it to my students.
Maybe you could also explain necroposting too - ie the pointlessness of posting a response like this to a thread that's seven years old - where the OP hasn't logged in in over five years and where the person who answered hasn't been on in three.
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