Question
Discuss the shape of:
on the basis of hybridization.
Solution
(i) Shape of PCl5:
In PCl5 , the central atom is 15P. The electronic configuration of phosphorus and chlorine atoms are as follows:
It is the case of sp3d hybridisation in which one 3s, three 3p and one 3d orbital of P-atom having nearly same energy intermix to give five sp3d hybrid orbitals. Now five hybrid orbitals are available for a combination which permits the formation of five covalent bonds with five chlorine atoms of PCl5
But all the hybridised orbitals are not equivalent. Three of these are oriented towards the three corners of an equilateral triangle making an angle of 120° between them. The bonds formed by there orbitals are known as equatorial bonds. Remaining two orbitals are oriented at right angles to the plane of the first set of three orbitals. Thus PCl5 has trigonal bipyramidal shape.
(ii) The shape of SF6: In SF6, the central atom is 16S. The electronic configuration of sulphur and fluorine atoms are as follows:
It is the case of sp3d2 hybridisation in which one 3s, three 3p and two 3d orbitals of S atom having nearly same energy intermix to give six sp3d2 hybrid orbitals. Now six hybrid orbitals are half filled.
Half filled 2p orbitals of six F atoms overlap with six-half filled sp3d2 hybrid orbitals of S-atom to form six sp3d2 p-p sigma bonds. So SF6 molecule has an octahedral structure.
In PCl5 , the central atom is 15P. The electronic configuration of phosphorus and chlorine atoms are as follows:
It is the case of sp3d hybridisation in which one 3s, three 3p and one 3d orbital of P-atom having nearly same energy intermix to give five sp3d hybrid orbitals. Now five hybrid orbitals are available for a combination which permits the formation of five covalent bonds with five chlorine atoms of PCl5
But all the hybridised orbitals are not equivalent. Three of these are oriented towards the three corners of an equilateral triangle making an angle of 120° between them. The bonds formed by there orbitals are known as equatorial bonds. Remaining two orbitals are oriented at right angles to the plane of the first set of three orbitals. Thus PCl5 has trigonal bipyramidal shape.
(ii) The shape of SF6: In SF6, the central atom is 16S. The electronic configuration of sulphur and fluorine atoms are as follows:
It is the case of sp3d2 hybridisation in which one 3s, three 3p and two 3d orbitals of S atom having nearly same energy intermix to give six sp3d2 hybrid orbitals. Now six hybrid orbitals are half filled.
Half filled 2p orbitals of six F atoms overlap with six-half filled sp3d2 hybrid orbitals of S-atom to form six sp3d2 p-p sigma bonds. So SF6 molecule has an octahedral structure.
