# How many electrons does each shell hold? [duplicate]

why some times 2nd shell onward it can hold 8 electrons and other times it is like they can hold K2 L8 M18 N32? when do i have to use first method(K2 L8 M8 N8) and when to use second method (k2 L8 M18)? I'm really confused.

• Hmm, have you learned about orbitals? – M.A.R. Apr 7 '15 at 12:42
• yes I have learn it already. I remember my teacher telling me that each shell can hold certain amount of electron (K2 L8 M18) But when i was looking through text book, in an example it says that potassium have electronic configuration 2,8,8,1 why it cant have 2,8,9? – student11 Apr 7 '15 at 13:20
• Have you learned about the subshells as well? The first shell only has $s$, the second one has $p$ and $s$, the third one has $d$ as well, and so forth. Also, you might take a look at here, if it helps. – M.A.R. Apr 7 '15 at 13:27
• No i haven't not yet. – student11 Apr 7 '15 at 14:05
• @student11 See my answer here, I have explained in detail the exact concern that you have. – Pritt says Reinstate Monica Jul 13 '17 at 4:44