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.
• C. All three electrons in K shell.
• 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.

$\bullet$ K shell is the 1^st orbit having the lowest energy. Electrons are filled from the lowest energy to highest energy shell i.e., the electrons are first filled in the K shell and then in L, M, N and so on.

$\bullet$ A shell can accomodate maximum of $2{\text{n}}^2$ electrons, where n denotes no. of shell.

$\bullet$ The K shell can accommodate only 2 electrons and the remaining one electron will be filled in L shell.

$\bullet$ Hence, the electronic configuration will be 2,1.