What is the maximum covalency if silicon

${}_{14}\mathrm{Si}\to 1{ \mathrm{s}}^{2}2{ \mathrm{s}}^{2}2{\mathrm{p}}^{6}3{ \mathrm{s}}^{2}3{\mathrm{p}}^{2}3{ \mathrm{d}}^0$

Silicon have vacant d-orbitals . So, it can expand its covalency up to 6

 Maximum cocavalency of silicon is Six , due to availability vacant d-orbitals