Question

the number of electrons in 3rd shell for an element with atomic number 20 is

Answer 1

The element whose atomic number 20 is calcium. Electronic configuration of calcium is :

K shell :-  2 electron

L shell :- 8 electron

M shell:- 8 electron

N shell:- 2 electron

In 3rd shell i.e M shell number of electron is 8.

Answer 2

8 electrons in 3rd shell