Question

Which of the following molecules contains maximum number of electrons in antibonding molecular orbitals?

• A. Li\(_2\)
• B. N\(_2\)
• C. O\(_2\)
• D. F\(_2\)

Hint:

Antibonding electrons increase across the period for diatomic molecules.

Answer 1

The Correct Option is D

Step 1: Electronic Configuration
Antibonding electrons ($N_a$): - $\text{Li}_2$ (Total 6e): $\sigma^*1s^2 \to N_a = 2$. - $\text{N}_2$ (Total 14e): $\sigma^*1s^2, \sigma^*2s^2 \to N_a = 4$. - $\text{O}_2$ (Total 16e): $\sigma^*1s^2, \sigma^*2s^2, \pi^*2p_x^1, \pi^*2p_y^1 \to N_a = 6$. - $\text{F}_2$ (Total 18e): $\sigma^*1s^2, \sigma^*2s^2, \pi^*2p_x^2, \pi^*2p_y^2 \to N_a = 8$.
Step 2: Conclusion
$\text{F}_2$ has the most electrons in antibonding orbitals.
Final Answer: (D)