The following graph is given, between total energy and distance between the two nuclei for species $H_{2}^{+}, H_{2}$ , $He_{2}^{+}$ & $He_{2}$ , which of the following statements is correct :

Question

The following graph is given, between total energy and distance between the two nuclei for species H 2 ​ + , H 2 ​ , He 2 + ​ & He 2 ​ , which of the following statements is correct :

TestHub · Accepted Answer

Bond dissociation energy (BDE) is directly proportional to the bond order of a chemical species. According to Molecular Orbital Theory, the bond order of H₂ is $1$ ( $σ_{1 s}^{2}$ ), whereas the bond order of He₂⁺ is $0.5$ ( $σ_{1 s}^{2} σ_{1 s}^{* 1}$ ).

Since H₂ has a higher bond order, it has a stronger bond and thus a higher bond dissociation energy than He₂⁺.

This is also confirmed by the graph, where the potential energy well for H₂ is significantly deeper than that of He₂⁺, indicating greater stability and BDE.

Chemistry - CHEMICAL BONDING Question with Solution | TestHub

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