Summarise the rules for writing of distribution of electrons in various shells for the first eighteen elements.
The rules for writing of distribution of electrons in various shells for the first eighteen elements are: (i) The maximum number of electrons present in a shell is formula—2n2 n = orbit number i.e., 1, 2, 3 Maximum number of electrons in different shells are: K shell n = 1 2n2 ⇒ 2(1)2 = 2 L shell n = 2 2n2 ⇒ 2(2)2 = 8 M shell n = 3 2n2 ⇒ 2(3)2 = 18 N shell n = 4 2n2 ⇒ 2(4)2 = 32 (ii) The maximum number of electrons that can be accommodated in the outermost orbit is 8. (iii) Electrons are not accommodated in a given shell unless the inner shells are filled. (Shells are filled step-wise).