Question

Explain hybridisation of the central atom in $SiC{l_4}$.

Answer 1

Structure and hybridisation of molecules can be explained using Valence Shell Electron Pair Repulsion Theory (VSEPR Theory). VSEPR Theory is used for explaining the structure of molecules. In this theory, structure is predicted based on the number of valence electrons present on the central atom of the molecule.

Complete step by step answer:
Given molecule is $SiC{l_4}$. The central atom will be the least electronegative atom. Hence here the central atom is silicon. We need to find the hybridisation of silicon.
Silicon is a Group $14$ element. Hence the number of valence electrons on silicon is four. We have four chlorine atoms. Each chlorine atom contains an unpaired electron on one of the p-orbital. Hence four orbitals are needed to satisfy all the electrons. Therefore, the four orbitals on silicon each containing one electron undergoes $s{p^3}$ hybridisation to form four identical $s{p^3}$ hybrid orbitals. Each of the hybrid orbital contains one electron. Then the p-orbital of four chlorine atoms containing one electron will overlap with the $s{p^3}$ orbitals to form sigma bonds. Hence there will be four sigma bonds between silicon and chlorine atoms. The silicon does not contain any lone pair of electrons, So the shape of $SiC{l_4}$ will be tetrahedral.
Hence hybridisation of the central atom in $SiC{l_4}$ is $s{p^3}$ and the molecule will be in tetrahedral shape.

Additional information-
The bond angle between chlorine and silicon will be ${109^0}$.

Note:
If there are any lone pair electrons present in the central atom, the $s{p^3}$ hybridisation will give other geometries. Shape of a molecule depends on hybridisation, number of bond pairs and number of lone pairs on the central atom.