The electronic configuration of halogen is

The correct option is ns² np5.

To understand why this is the correct electronic configuration for halogens, let's break down the concepts step-by-step:

1. Position in the Periodic Table:
Halogens are a group of chemical elements in the periodic table. They belong to Group 17 (formerly known as Group VIIA). This group includes elements such as fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

2. Valence Electrons:
The group number of a representative element indicates the number of valence electrons (electrons in the outermost shell) it possesses. For Group 17 elements, the number of valence electrons is:
17 - 10 = 7 valence electrons.

3. Filling of Subshells:
In any given period n, the outermost shell consists of the s and p subshells.
The s subshell can hold a maximum of 2 electrons, which is written as:

$${\mathrm{ns}}^2$$

Subtracting these 2 electrons from the total of 7 valence electrons leaves 5 electrons to occupy the p subshell. The p subshell configuration is therefore written as:

$${\mathrm{np}}^5$$

Combining these gives the general outer electronic configuration for all halogens:

$${\mathrm{ns}}^2{\mathrm{np}}^5$$

4. Examples:
• Fluorine (F, Z = 9): $1s^{2}2s^{2}2p^5$ (where outer shell n = 2, configuration is $2s^{2}2p^5$)
• Chlorine (Cl, Z = 17): $1s^{2}2s^{2}2p^{6}3s^{2}3p^5$ (where outer shell n = 3, configuration is $3s^{2}3p^5$)