H2O exhibits a bent molecular geometry with a 104.5° bond angle, diverging from the ideal tetrahedral angle due to lone pair-bond pair repulsion as per VSEPR theory. Its structure, determined by sp^3 hybridization of the oxygen atom, accommodates 2 lone pairs and 2 bonding pairs, leading to a significant reduction in bond angle from the tetrahedral 109.5° to optimize electron pair repulsion minimization.
Molecular Geometry And Bond Angles of H2O
Geometry
The molecular geometry of H2O is bent or V-shaped. This is because the central oxygen atom is surrounded by two hydrogen atoms and two lone pairs of electrons. The presence of these lone pairs causes the repulsion between electron pairs, resulting in a bent shape.
Bond Angles
The bond angle in H2O is approximately 104.5 degrees. This angle is less than the ideal tetrahedral angle of 109.5 degrees due to the presence of the lone pairs on the oxygen atom. The lone pairs exert greater repulsion on the bonding pairs, pushing the hydrogen atoms closer together and resulting in a smaller bond angle.
Contribution of Bonds and Lone Pairs
The type and number of bonds, as well as the presence or absence of lone pairs on the central atom, contribute to the overall shape of the molecule. In the case of H2O:
- The oxygen atom forms two single bonds with the two hydrogen atoms, resulting in a linear shape if there were no lone pairs. However, the presence of two lone pairs on the oxygen atom distorts the shape to a bent or V-shaped geometry.
- The lone pairs on the oxygen atom repel the bonding pairs, causing the hydrogen atoms to move closer together and resulting in a smaller bond angle.
The following table summarizes the contributions of bonds and lone pairs to the molecular geometry and bond angles of H2O:
| Central Atom | Type and Number of Bonds | Presence of Lone Pairs | Molecular Geometry | Bond Angle |
|---|---|---|---|---|
| Oxygen (O) | Two single bonds | Two lone pairs | Bent or V-shaped | 104.5° |
Note: Lone pairs are represented by non-bonding electron pairs on the central atom.
Read More:
Hello everyone, I am Dr. Shruti M Ramteke, I did my Ph.D. in chemistry. I am passionate about writing and like to share my knowledge with others . Feel free to contact me on linkedin