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H2O molecule is a triatomic molecule but its geometry is not linear. Why?

Molecular Structure

The classic model for the water molecule (H2O ) is a central oxygen atom bonded to two hydrogen atoms on either side. Unlike other triatomic species that have a linear shape, the bonds on a water molecule are tilted at a slight angle, due to the presence of lone-pair electrons on the oxygen atom. Through VSEPR theory, it is shown that H2O has a steric number of 4, with two lone pairs and two bond pairs, making its molecular geometry "bent". As a result, the angle between the two oxygen-hydrogen bonds are approximately 104.5°, which is slightly smaller than the angle typically found in tetrahadral-shaped molecules. This is due to the particularly strong repulsions by the lone-pair electrons on the oxygen atom, which pushes the hydrogens closer together than usual.  Each of the oxygen-hydrogen bonds measure approximately 95.84pm in length. This bent geometry due to the presence of lone pair electrons makes water different from typical linear triatomic species, both on an atomic and a macroscopic level.


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