Answer: This is because of the presence of lone pairs ion water molecule.
Explanation:
To calculate the hybridization, we use the formula:
[tex]{\text{Number of electrons}} =\frac{1}{2}[V+N-C+A][/tex]
where, V = number of valence electrons present in central atom
N = number of monovalent atoms bonded to central atom
C = charge of cation
A = charge of anion
[tex]{\text{Number of electrons}} =\frac{1}{2}[6+2-0+0]=4[/tex]
The number of electrons is 4 that means the hybridization will be [tex]sp^3[/tex] and the electronic geometry of the molecule will be tetrahedral. But as there are two atoms around the central oxygen atom, the two other positions are occupied by the lone pair of electrons. Now, the molecular geometry of the molecule becomes bent.
[tex]{\text{Number of electrons}} =\frac{1}{2}[4+4-0+0]=4[/tex]
The number of electrons is 4 that means the hybridization will be [tex]sp^3[/tex] and the electronic geometry of the molecule will be tetrahedral. As, all the positions around the central metal atom which is carbon are occupied, so no lone pair of electrons are present.
As, the repulsions between lone pair and bond pair is more, so the bond angle which should be 109.5° has decreased to an angle of 104.5° in water.
