What are electron-deficient compounds? Are $BCl_3$ and $SiCl_4$ electron-deficient species? Explain.

(N/A) Electron-deficient compounds are those in which the central atom has an incomplete octet,meaning it has fewer than $8$ electrons in its valence shell.
$(i)$ $BCl_3$: In $BCl_3$,the Boron atom has $3$ valence electrons. After forming $3$ covalent bonds with chlorine atoms,it has $6$ electrons in its valence shell. Since $6 < 8$,$BCl_3$ is an electron-deficient species.
$(ii)$ $SiCl_4$: Silicon has $4$ valence electrons. After forming $4$ covalent bonds with chlorine atoms,it completes its octet with $8$ electrons. Therefore,$SiCl_4$ is not an electron-deficient species.