Question

The possible value of $l$ and $m$ for the last electron in the $C{l}^{-}$ ion are:

• A. 1 and 2
• B. 2 and +1
• C. 3 and -1
• D. 1 and -1

Answer 1

The correct option is D 1 and -1

The electronic configurations of $Cl$ and $C{l}^{-}$ are:
$Cl=\left[Ne\right]3s^{2}3p^5$
$C{l}^{-}=\left[Ne\right]3s^{2}3p^6$

Since the last electron in the chloride anion is entered in the $3p$ orbital, therefore $l$ = 1 and $m$ is any one of 1, 0, -1.