Question

What are electron deficient compounds? Are $BCl_{3}$ and $SiCl_{4}$ electron deficient species? Explain.

Answer 1

The center of metal atom has octet electrons which is incomplete is the phenomenon of electron deficient compounds. ${ BCl }_{ 3 }$ is the compounds with electron deficient.

(i) ${ BCl }_{ 3 }$

Boron has three numbers of valence electrons. After the formation of “three covalent bonds with chlorine”, the number of electron increases to 6. To reach octet it needs two electrons.

(ii) ${ SiCl }_{ 4 }$

Silicone has valence electrons of four. By the formation of covalent bonds four atoms of chlorine its number of electron increases to eight. Hence the rule of octet is obeyed. Silicon Tetrachloride is not a compound with electron deficient.

Answer 2

Answer :

Electron deficient hydrides: Compounds in which central atom has incomplete octet, are called electron deficient hydrides. For example, BeH2, BH3 are electron deficient hydrides.

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(ii) Electron precise hydrides: Those compounds in which exact number of electrons are present in central atom or the central atom contains complete octet are called precise hydrides e.g., CH4, SiH4, GeH4 etc. are precise hydrides.

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(iii) Electron rich hydrides: Those compounds in which central atom has one or more lone pair of excess electrons are called electron rich hydrides, e.g.,NH3, H2O.