Question

Which of the following is the correct order of electron affinity?

• A. I $>$ Br $>$ F $>$ Cl
• B. F $<$ Cl $<$ Br $<$ I
• C. F $>$ Cl $>$ Br $>$ I
• D. I $<$ Br $<$ F $<$ Cl

Hint:

Remember: \textbf{Chlorine has the highest electron affinity among halogens}, not fluorine, due to less inter-electronic repulsion.

Answer 1

The Correct Option is D

Step 1: Recall the meaning of electron affinity. Electron affinity is the energy released when an electron is added to a neutral gaseous atom.
Step 2: In halogens, electron affinity generally increases up the group due to decreasing atomic size.
Step 3: However, fluorine has slightly lower electron affinity than chlorine because of strong electron–electron repulsion in its very small 2p orbital.
Step 4: Therefore, the correct order of electron affinity among halogens is: \[ \text{Cl}>\text{F}>\text{Br}>\text{I} \]
Step 5: Writing this in increasing order: \[ \text{I}<\text{Br}<\text{F}<\text{Cl} \]
Step 6: Hence, the correct option is (D).