electronic configuration

scientifico

Hello, why in the normal atomic configuration every layer except the second can contain only up to 8 electrons if for example the level with quantic number 3 contain up to 18 electrons?
What relation is there between this two models?

Thank you!

alxm

You have the K,L,M,N (and so on) shells, which contain 2,8,18,32.. electrons.

Those numbers come from the sub-shells which make up the shells, which are denoted s,p,d,f.
The sub-shells contain 2, 6, 10, 14 electrons, respectively. (twice the odd numbers 1,3,5,7)

The K shell contains only an s sub-shell, so it has two electrons in total. The L shell has one s and one p, giving 2+6=8 electrons in total.
The M shell has an s,p and d, so 2+6+10 = 18, and the N shell has an f sub-shell as well, so 2+6+10+14 = 32 electrons.

scientifico

An electron in the last layer require less energy to be removed, so why the last layer has more energy than the layer nearest the nucleum?