Why do 8 electrons form a stable shell?  [ENDORSED]

Science questions not covered in Chem 14A and 14B. Try to limit questions to chemistry (inorganic chemistry, physical chemistry, organic chemistry, biophysical chemistry, biochemistry, materials science, environmental chemistry).

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Ace 3F
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Why do 8 electrons form a stable shell?

Postby Ace 3F » Sun Mar 12, 2017 8:06 pm

I'm pretty sure that others have probably gone over this before but I don't recall having learned why exactly it is 8 electrons that form a stable shell, I know it has to do with electron spins although I'm not sure what dictates it exactly.

Thank you!

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Re: Why do 8 electrons form a stable shell?

Postby Alexandra_Shambayate_2L » Sun Mar 12, 2017 9:11 pm

Noble gases have eight electrons and they are considered the most stable elements, therefore it is most ideal and stable for other elements to have a shell of eight electrons to be at its most stable point.

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Re: Why do 8 electrons form a stable shell?  [ENDORSED]

Postby Chem_Mod » Sun Mar 12, 2017 9:47 pm

In the p-block it is the result of filled s and p subshells = 8e-
s, px, py, pz

Most of the covalent bonds in molecules involve p-block elements, hence our octet guideline for most molecules, especially biological compounds involving C, O, N, Cl.

In the d-block it is 18e- due to the s, p, and 5 d-states.

Ask me after class if this is not clear.

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