Why is the electron gain enthalpy of O or F less than that of S or Cl?

Question

Why is the electron gain enthalpy of O or F less than that of S or Cl? (A) O and F are more electronegative than S and Cl. (B) When an electron is added to O or F, it goes to a smaller (n = 2) level and suffers more repulsion than the electron in S or Cl in larger level (n = 3). (C) Adding an electron to 3p-orbital leads to more repulsion than 2p-orbital. (D) Electron gain enthalpy depends upon the electron affinity of the atom.

Tardigrade Admin · Accepted Answer

There is more repulsion for the incoming electron when the size of atom is smaller.

Q. Why is the electron gain enthalpy of $O$ or $F$ less than that of $S$ or $Cl$ ?

O and F are more electronegative than S and Cl.

When an electron is added to O or F, it goes to a smaller $(n = 2)$ level and suffers more repulsion than the electron in S or Cl in larger level $(n = 3)$ .

Adding an electron to 3p-orbital leads to more repulsion than 2p-orbital.

Electron gain enthalpy depends upon the electron affinity of the atom.

There is more repulsion for the incoming electron when the size of atom is smaller.

Q. Why is the electron gain enthalpy of O or F less than that of S or Cl?

O and F are more electronegative than S and Cl.

When an electron is added to O or F, it goes to a smaller (n=2) level and suffers more repulsion than the electron in S or Cl in larger level (n=3).

Adding an electron to 3p-orbital leads to more repulsion than 2p-orbital.

Electron gain enthalpy depends upon the electron affinity of the atom.

There is more repulsion for the incoming electron when the size of atom is smaller.

Q. Why is the electron gain enthalpy of $O$ or $F$ less than that of $S$ or $Cl$ ?

When an electron is added to O or F, it goes to a smaller $(n = 2)$ level and suffers more repulsion than the electron in S or Cl in larger level $(n = 3)$ .