Explain, with suitable examples, the following:
(i) Electron-deficient.

Explanation

Dihdrogen forms molecular compounds with most of the p - block elements. These are type.
(i) Electron-deficient hydrides: These are formed by elements of 13 group (Boron family). In these hydrides the electrons available are not sufficient for making the bonds. They do not have octet around the central atom. So they act as Lewis acids. Eg: Diborane `B_(2)H_(6)`.
For writing the Lewis structure the number of available electrons are 12 but required are 14.