Hydrides: Dihydrogen combines with almost all elements except noble gases to form binary compounds under certain conditions.
e. g. MgH2, B2H6 etc.
Types of hydrides:
The hydrides are classified into three categories-
(i) Ionic Hydrides:
These are stoichiometric compounds of dihydrogen formed with most of the s-block elements which are highly electropositive in nature. These are also called saline hydrides. e. g NaH, CaH2 etc
(ii) Covalent Hydrides:
These are stoichiometric compounds of dihydrogen formed with most of the p-block elements which have low electropositivity. These are also called molecular hydrides.
eg. CH4, NH3,H2O,HF, etc
(iii) Metallic Hydrides:
These are non-stoichiometric compounds of dihydrogen formed with d-block and f-block elements. However, the metals of group 7, 8 and 9 do not form hydride.
e. g LaH2.55, ZrH1.3−1.75 etc