Predict the shapes of the following molecules on the basis of hybridisation.
BCl3,CH4,CO2,NH3.
Predicting shapes of given molecules using hybridisation
Hybridization is the process of intermixing of the orbitals of slightly different energies so as to redistribute their energies which results in the formation of new set of orbitals of equivalent energies and shape.
Hybridization helps in deciding the structure of the molecules.
Electron pair types
Total number of hybrid orbitals = No. of lone pairs on central atom + bond pair (i.e. Number of sigma bonds formed by central atom)
Hybridisation can be predicted by using the number of total hybridised orbitals
Molecules | Hybrid orbitals=lone pairs +sigma bonds | Hybridisation | Shape |
BCl3 | 0+3=3 | sp2 |
Trigonal planar |
CH4 | 0+4=4 | sp3 |
Tetrahedral |
CO2 | 0+2=2 | sp |
Linear |
NH3 | 1+3=4 | sp3 |
Pyramidal |
There, NH3 is having pyramidal shape despite having sp3 hybridisation because central atom (N) contains one lone pair of electron due to which when this lone pair and 3 sigma bonds will correspond to 4 vertices of tetrahedron, it will give rise to pyramidal shape.