Which one of the following arrangements represents the correct order of electron gain enthalpy (with negative sign) of the given atomic species?

Question

Which of the following is the correct decreasing order of electronegativity?

Answer 1

To determine the correct order of electron gain enthalpy with negative sign among the given atomic species Cl, F, S, and O, we need to understand the concept of electron gain enthalpy.

Electron Gain Enthalpy:

Electron gain enthalpy is the amount of energy released when an electron is added to a neutral atom in the gaseous state to form a negatively charged ion.
The more negative the electron gain enthalpy, the greater the tendency of an atom to accept an electron.
Generally, electron gain enthalpy becomes more negative across a period from left to right in the periodic table and less negative down a group.

Order of Electron Gain Enthalpy (with negative sign):

For the elements involved here:

Chlorine (Cl): Chlorine has a very high electron affinity, making its electron gain enthalpy highly negative.
Fluorine (F): Although fluorine is most electronegative, it has a smaller size, which leads to high inter-electronic repulsion in the compact 2p orbital, making its gain enthalpy less negative than chlorine.
Sulfur (S) and Oxygen (O): Sulfur has a less negative electron gain enthalpy compared to chlorine and fluorine, but more negative than oxygen. Oxygen's high electron density in the 2p orbital reduces its tendency to gain an additional electron compared to sulfur.

Thus, the increasing order of electron gain enthalpy (with negative sign) for these elements is:

O < S < F < Cl

Conclusion: The correct arrangement representing the order of electron gain enthalpy (with negative sign) of the given atomic species is O < S < F < Cl.

This matches the correct option provided in the question:

Correct Answer: O < S < F < Cl

Answer 2