If Electronegativity of Cl is greater than H2 then why is the bond angle of Cl2O greater than H2O? Cl2 has more EN than H2 and size of Cl2 is more than H2 but if we go according to EN then more angle should be of H2O as electrons in H2O would more nearer to O2 than the electrons in Cl2O near to O2?

  • $\begingroup$ Steric strain possibly, due to the atomic radius of Chlorine being significantly larger than that of Hydrogen. $\endgroup$ Oct 5, 2020 at 16:37

1 Answer 1


Bond angle is largely governed by the location of electron cloud with regard to atoms in a molecule.

In dichlorine monoxide, the electron cloud is more spread out between oxygen and chlorine while in the water molecule it’s much closer to the oxygen atom. Therefore, the net bond paid-bond pair repulsion is higher in dichlorine monoxide than in water, while the lone pair-lone pair repulsion is almost the same.

You can see the relative sizes of oxygen, hydrogen and chlorine atoms. This is dichlorine monoxide.

Water molecule

Also, chlorine atoms are much bigger than hydrogen atoms, because of which they also undergo steric repulsion causing the bond angle to further increase.

That’s why the bond angle in dichlorine monoxide is greater than in the water molecule.


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