What do you understand by (i) electron-deficient, (ii) electron-precise, and (iii) electron-rich compounds of hydrogen? Provide justification with suitable examples ?

Group 13 hydrides (Compounds with hydrogen), mainly Hydrides of Al and B are called electron deficient hydrides.
Elements of this group have 3 valence electrons and therefore can only form bonds with 3 hydrogen atoms. After forming 3 bonds, the central atom has only 6 electron around it which is 2 electrons short than Which is require for completing octet.
And these hydrides cannot be represented by simple Lewis structure, these have tendency to accept electrons as electrone deficient. For example BH₃
While electron precise hydride is the type of hydride in which the number of electrons present is equal to the number of electron required (octet or duplet). For example- CH₄
Electron rich hydride is the type of hydride in which the no. of electrons present are more than the no. of electron required for making octet. For example- NH3

Dear Student

(i) Electron Deficient Hybrides – Group 13 hydrides(Compounds with hydrogen), mainly Hydrides of Al and B are calledelectron deficient hydrides.
Example BH₃

(ii) Electron Precise Hydride –The type of hydride in which the number of electrons present is equal to the number of electron required (octet or duplet).
Example- CH₄


(iii) Electron Rich Hydride – The type of hydride in which the no. of electrons present are more than the no. of electron required for making octet.
Example- NH₃

I hope this answer will help you.
Thanks & Regards
Yash Chourasiya