Question

Which of the following element is not an s-block element?

• A. Sodium (Na)
• B. Aluminium (Al)
• C. Potassium (K)
• D. Lithium (Li)

Answer 1

The correct option is B Aluminium (Al)

$\bullet$ The subshell electronic configuration of given elements is given below.
Sodium (Na) - $1s^{2}2s^{2}2p^{6}3s^1$
Aluminium (Al) - $1s^{2}2s^{2}2p^{6}3s^{2}3p^1$
Potassium (K) - $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^1$
Lithium (Li) - $1s^{2}2s^1$

$\bullet$ If the element gets its new coming electron (differentiating electron) into 's' subshell, then it is classified as 's' block element.

$\bullet$ If the element gets its new coming electron (differentiating electron) into 'p' subshell, then it is classified as 'p' block element.

$\bullet$ Only aluminium has its last electron in p subshell. Therefore it is a p-block element.