orbitals. The three hybrid orbitals so formed are oriented in a trigonal planar arrangement and overlap with p orbitals of chlorine to form three B-Cl bonds. Therefore, in BCl (Fig. .
), the geometry is trigonal planar with ClBCl bond angle of °. (III) sp hybridisation: This type of hybridisation can be explained by taking the example of CH molecule in which there is mixing of one s -orbital and three p -orbitals of the valence shell to form four sp hybrid orbital of equivalent energies and shape. There is % s -character and % p -character in each sp hybrid orbital. The four sp hybrid orbitals so formed are directed towards the four corners of the tetrahedron.
The angle between sp hybrid orbital is . ° as shown in Fig. . .
Fig. . Formation of sp hybrids by the combination of s, p x , p y and p z atomic orbitals of carbon and the formation of CH molecule σ σ σ σ The structure of NH and H O molecules can also be explained with the help of sp hybridisation. In NH , the valence shell (outer) electronic configuration of nitrogen in the ground state is S p p p x y z having three unpaired electrons in the sp hybrid orbitals and a lone pair of electrons is present in the fourth one.
These three hybrid orbitals overlap with s orbitals of hydrogen atoms to form three N–H sigma bonds. We know that the force of repulsion between a lone pair and a bond pair is more than the force of repulsion between two bond pairs of electrons. The molecule thus gets distorted and the bond angle is reduced to ° from . °.
The geometry of such a molecule will be pyramidal as shown in Fig. . . Fig.
. Formation of NH molecule In case of H O molecule, the four oxygen orbitals (one s and three p ) undergo sp hybridisation forming four sp