Question

The correct pair of electron affinity order is:

• A. O>S, F>CI
• B. OF
• C. S>O, F>CI
• D. SF

Answer 1

The Correct Option is B

The correct pair of electron affinity order is O < S, Cl > F.

Here's why:

• Electron Affinity: Electron affinity is the change in energy (in kJ/mol) of a neutral atom (in the gaseous phase) when an electron is added to the atom to form a negative ion. More negative values indicate a higher (more favorable) electron affinity.
• Oxygen vs. Sulfur: Generally, electron affinity becomes more negative as you move from left to right across a period in the periodic table. However, there are exceptions. Oxygen has a smaller (less negative) electron affinity than sulfur. This is because oxygen has a relatively small size, and adding an electron results in significant electron-electron repulsion in the compact 2p orbitals, making it less favorable than adding an electron to the larger sulfur atom. Sulfur has more space in its 3p orbitals, so the electron repulsion is less.
• Fluorine vs. Chlorine: Similar to oxygen, fluorine is a small atom, leading to relatively strong electron-electron repulsions when an electron is added to the 2p orbitals. Chlorine, being larger, experiences less electron repulsion in its 3p orbitals, so its electron affinity is more negative than fluorine.

Therefore, the correct electron affinity order is O < S and Cl > F.

Correct Answer: O < S, Cl > F