Question

What is the electronic configuration of ${}_{18}^{40}\text{Ar}$?

• A. 1, 8, 9
• B. 2, 8, 8
• C. 2, 8, 8, 3
• D. 2, 8, 18, 12

Answer 1

The correct option is B 2, 8, 8

$\bullet$ The maximum number of electrons that a shell can accommodate is given by $2n^2$, where $n$ is the shell number.

$\bullet$ The atomic number of argon $\left(Ar\right)$ is 18 and its electronic configuration is:
$$\begin{array}{cccc}\text{Shell}& \text{K}& \text{L}& \text{M}\\ \text{No. of electrons}& \text{2}& \text{8}& \text{8}\end{array}$$