## principal quantum numbers

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### principal quantum numbers

I understand that when n, the principal quantum number, increases, the size of the shell of the atom also increases. But, why do increasing values of n also corresponding to increasing energy of the orbital?

Tatiana Hage 2E
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### Re: principal quantum numbers

This link might help explain it:
http://chemed.chem.purdue.edu/genchem/t ... antum.html

"Because they have opposite electrical charges, electrons are attracted to the nucleus of the atom. Energy must therefore be absorbed to excite an electron from an orbital in which the electron is close to the nucleus (n = 1) into an orbital in which it is further from the nucleus (n = 2). The principal quantum number therefore indirectly describes the energy of an orbital."

Ryan Sydney Beyer 2B
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### Re: principal quantum numbers

The most important factor which influences the energy of an orbital is the size which is related to the principal quantum number. For an atom that contains just 1 electron there is no difference between the energies in the different subshells. As soon as an atom contains more than 1 electron, the different subshells won't have the same energy. Within any shell, the s orbital will always have the lowest energy. The energy of the subshells increase as the angular quantum number (l) becomes larger. Because of this, two factors control the energy of an orbital for the majority of atoms: the size of the orbital, and the shape of the orbital. Hope this helps!