IAT IISER2026ChemistryChemical Bonding and Molecular Structure
What is the order of bond energy between C=S & C=Te, and between Cl–Cl & F–F?
Options
- AC=Te > C=S and F–F > Cl–Cl
- BC=S > C=Te and F–F > Cl–Cl
- CC=S > C=Te and Cl–Cl > F–F
- DC=Te > C=S and Cl–Cl > F–F
Correct answer
C. C=S > C=Te and Cl–Cl > F–F
Step-by-step solution
The bond energy of C=S is greater than that of C=Te because the 2p - 3p orbital overlap in C=S is more effective than the 2p - 5p orbital overlap in C=Te. As the size of the bonded atom increases, the extent of overlap decreases, leading to a weaker bond. The bond energy of Cl-Cl is greater than that of F-F. Although F is smaller and expected to form a stronger bond, the extremely small size of the F atom results in strong interelectronic repulsions between the lone pairs on the two bonded F atoms. This repulsion w