Question

Which has the larger bond angle H₂S or H₂O and why?

Answer 1

1. H₂O has a larger bond angle (104.5°) compared to H₂S (92.1°).
2. Oxygen in H₂O is more electronegative than sulphur in H₂S, so it holds bonding electrons more tightly.
3. This increases electron density around oxygen, causing greater repulsion between lone pairs and bond pairs.
4. Lone pair bond pair repulsion compresses the bond angle less in H₂O but more in H₂S.
5. Down the group, central atom size increases and electronegativity decreases, reducing repulsion and bond angle.
6. As a result, bond angles decrease from H₂O to H₂Te.

Hence, H₂O has the larger bond angle due to stronger lone pair repulsion on oxygen.