Question

Describe bonding in water molecule using VBT. Show the overlap of hybridised orbitals leading to the

formation of H2O molecule. Account for the bond angle 104.5o​

Answer 1

The bonding in a water molecule involves the overlap of atomic orbitals to form hybrid orbitals. The oxygen atom undergoes sp³ hybridization, resulting in four equivalent hybrid orbitals that point approximately towards the corners of a tetrahedron. The observed bond angle in water is 104.5°, which is less than the predicted tetrahedral angle of 109.5°.

Step-by-step explanation:

The bonding in a water molecule involves the overlap of atomic orbitals to form hybrid orbitals. In valence bond theory, the two 2p orbitals of the oxygen atom and the 1s orbitals of the hydrogen atoms overlap to form two sigma bonds. The oxygen atom undergoes sp³ hybridization, resulting in four equivalent hybrid orbitals that point approximately towards the corners of a tetrahedron. Two of these hybrid orbitals form sigma bonds with the hydrogen atoms, while the other two hybrid orbitals contain lone pairs.

The observed bond angle in water is 104.5°, which is less than the predicted tetrahedral angle of 109.5°. This distortion occurs due to the repulsion between the lone pairs of electrons, which occupy more space than the bonding pairs. The bonding pairs are pushed closer together, resulting in a smaller bond angle.

Answer 2

Ground state electronic configuration of oxygen atom is as follows - is 1s2 2s2 2p2x 2p1y 2p1z 1s2 2s2 2px2 2py1 2pz1

Ground state electronic configuration of hydrogen atom is 1s1 1s1

Step-by-step explanation:

As per the Valence Bond Theory (VBT),

Ground state electronic configuration of oxygen atom is as follows - is 1s2 2s2 2p2x 2p1y 2p1z 1s2 2s2 2px2 2py1 2pz1

Ground state electronic configuration of hydrogen atom is 1s1 1s1

Considering the electronic configuration, H-O-H bond angle would be at 90 degrees as 2py2py and 2pz2pz are oriented 90° with respect to each other. But if the oxygen atomic orbitals is used directly then bond angle for water is 104.45° as per the VSEPR theory which states that 2s2s spherical orbit in oxygen can adjust the bond angle by creating new hybrid orbitals