Question

If an element has 3 electrons in total, how will you distribute it among the shells?

• A. 2 electrons in L shell and 1 electron in K shell
• B. All three electrons in L shell itself
• C. All three electrons in K shell itself
• D. 2 Electrons in K shell and 1 electron in L shell

Answer 1

The correct option is D

2 Electrons in K shell and 1 electron in L shell

K shell is the $1^{st}$ orbit which has the lowest energy. Filling of the electrons happen from the lower energy shells closer to the nucleus before they move into the higher energy shells.

The electrons are first filled in the K shell and then remaining electrons are filled in L shell, then M shell and so on.

Since, according to 2$\times$ $n^2$ formulae, the K shell can accommodate only 2 electrons and the remaining electrons are filled in L shell.