CCL4 cannot be hydrolysed where as SiCL4 undergoes hydrolysis why?????

CCl₄ is not hydrolyzed as SiCl₄ because of two reasons:

1. Carbon does not have d-orbitals because it is found in 2nd period i.e. second shell so as the 3d -orbitals are not available and so it can not expand its co-ordination no. above 4.

Since, in carbon tetrachloride (CCl₄) all the valencies are satisfied, so it can not add any water molecule by any mean so the reaction becomes ;

CCl₄ + H₂O ---> No reaction.

While in case of silicon, it exists in period 3, which has 3d-orbitals vacant , and so it can expand its octet and can have the co-ordination no. above four so that the additional water molecule can donate a lone pair of electron to the Silicon, thus the reaction becomes:

2. Due, to smaller size of C-atom it is shielded by the larger Cl-atoms while in case of Silicon due to larger size, the extent of shielding is not that large and so attack of water is possible for hydrolysis.