CHEMISTRY · Multi-part · CBSE · Chemistry · Chemical Bonding and Molecular Structure · Chemical Bonding and Molecular Structure
Problem
Three potential–energy curves, labelled A, B, and C, describe the interaction between the nuclei of two identical atoms of element X. A textual description of the curves is provided below.
• Curve A reaches its minimum potential energy of –350 kJ·mol⁻¹ at an internuclear distance of 74 pm.
• Curve B reaches its minimum potential energy of –150 kJ·mol⁻¹ at an internuclear distance of 134 pm.
• Curve C reaches its minimum potential energy of –250 kJ·mol⁻¹ at an internuclear distance of 97 pm.
Assume that the vertical energy scale and the horizontal distance scale are identical for all three curves.
(a) Rank the three bonds represented by curves A, B, and C in order of increasing bond order (single, double, triple).
(b) Justify your ranking in part (a) by referring explicitly to specific numerical features of the curves.
(c) The stiffness of a bond can be approximated by the steepness of the potential–energy curve near the equilibrium point. Describe which curve corresponds to the stiffest bond and explain your reasoning.