My textbook says that interhalogen compounds are more reactive than halogens, because the $\ce{X-X}$ bond in halogens (for example, dichlorine or $\ce{Cl2}$) is stronger than the $\ce{X-X'}$ bond in interhalogens (for example, chlorine monofluoride or $\ce{ClF}$).

(In the symbols that I have used, $\ce{X}$ and $\ce{X'}$ have been used to denote dissimilar halogen atoms.)

So my question is: why is the bond between dissimilar halogens weaker than the bond between atoms of the same halogen?

I am aware that the bond between two identical atoms will be a completely covalent bond due to no difference in the electronegativities of the participant atoms. So, the $\ce{X-X}$, bond as in $\ce{Cl2}$ will have no ionic character.

In case of an interhalogen compound, however, the difference in the elecronegativities of the (dissimilar) participant atoms will cause the bond to become polar and thereby acquire ionic character.

So is it the ionic character of the interhalogen compounds that causes them to be more reactive than halogens? But then, this means that ionic bonds are weaker than covalent bonds.

But, the answers here as well as here say that an ionic bond is stronger.

But this link says the very opposite. Okay, the people writing the answers there have written it to suit an eight grader's understanding, but even so, they have stated that covalent bonds are stronger than ionic bonds.

So which alternative am I to believe? I know that most bonds are neither purely ionic not purely covalent, but intermediate between these two extreme characters, but this only serves to increase my bewilderment.

Can somebody please resolve this, or tell me where I have gone wrong in my reasoning as regards the reactivities of the interhalogen compounds in comparison with halogens?

And finally, please tell me the reason why interhalogens are more reactive. Thanks!


1 Answer 1


Here is the answer for which bond (ionic or covalent) is stronger. There is no direct answer to this question as it depends on atoms that take part in bond formation.For example you might be knowing that a Fluorine- Fluorine bond is weaker than a chlorine-chlorine bond due to high inter electronic repulsion.In another example iodine-iodine bond is weaker than chlorine-chlorine bond.Similarly there is certainly this sort of variation in ionic bond as well. So if you compare the weakest ionic bond and strongest covalent bond then covalent bond would be stronger.And if you compare stongest ionic bond and weakest covalent bond, then of course ionic bond would be stronger.Also in many substances its not only the bond strength that matters but also the crystal structure. An example where covalent bond is stronger:Carbon-Carbon bond is stronger than NaCl bond. Whereas NaCl ionic bond is more stronger than Br-Br covalent bond.

So it depends on the atoms that participate in bond formation.

visit https://labs.chem.ucsb.edu/zakarian/armen/11---bonddissociationenergy.pdf for bond enthalpy.


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