Which is an outer electron configuration of a halogen
The correct answer and explanation is :
Correct Answer:
The outer electron configuration of a halogen is ns² np⁵.
Explanation (Approx. 300 words):
Halogens are a group of elements found in Group 17 (or VIIA) of the periodic table. This group includes fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). All halogens have a similar outer electron configuration, which plays a critical role in their chemical behavior.
The general outer electron configuration of a halogen is ns² np⁵, where:
- n represents the principal quantum number (energy level) that varies depending on the period (row) in which the element is located.
- s² means two electrons fill the s orbital.
- p⁵ means there are five electrons in the p orbital, which can hold a maximum of six.
This configuration shows that halogens have seven valence electrons, just one electron short of a full octet, which makes them highly reactive, especially with alkali metals and alkaline earth metals, which readily lose electrons.
For example:
- Fluorine (F) is in Period 2, so its outer configuration is 2s² 2p⁵.
- Chlorine (Cl) is in Period 3, with 3s² 3p⁵.
- Bromine (Br) is in Period 4, with 4s² 4p⁵, and so on.
This tendency to gain one electron to complete the octet explains why halogens typically form -1 anions (e.g., Cl⁻) and why they are so reactive. Their high electronegativity and reactivity decrease as you move down the group due to increasing atomic size and electron shielding.
In summary, the ns² np⁵ configuration makes halogens very reactive nonmetals with strong tendencies to form salts (ionic compounds) and explains much of their chemistry in biological, industrial, and environmental contexts.