Question

Number of valence electrons in Chlorine ion are: (a) 16 (b) 8 (c) 17 (d) 18

• A. $16$
• B. 8
• C. 17
• D. 18

Answer 1

The correct option is B

8

Explanation for correct answer

(B) $\mathbf{8}$

1. Valence electrons are defined as electrons in the outermost shells that are not filled.
2. The electronic configuration of Chlorine $\left(\mathrm{Cl}\right)=1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^5$, therefore Chlorine exists as ${\mathrm{Cl}}^{-}$ ion, the electronic configuration should be $\left({\mathrm{Cl}}^{-}\right)=1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^6$
3. Hence there are eight valence electrons in chlorine ion, option (B) is correct.

Explanation for incorrect answer

(A) $\mathbf{16}$

1. There are total of 16 electrons in the oxygen or chalcogen series means six electrons in the valence shell.
2. Hence option (A) is incorrect.

(C) $\mathbf{17}$

1. There are total of seventeen electrons not valence electrons in chlorine atom.
2. Electronic configuration:$\left(\mathrm{Cl}\right)=1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^5$
3. Hence, option (C) is incorrect.

(D) $\mathbf{18}$

1. There are 18 total electrons in the chlorine ion not valence electrons.
2. Electronic configuration: $\left({\mathrm{Cl}}^{-}\right)=1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^6$
3. Hence option (D) is incorrect.

Therefore, the total number of valence electrons in chlorine ion is Eight. Hence option (B) is correct.