if the valency of h2 is +1 then why sometimes it forms ionic hydrides? it means tht this disobeying the rule that "in order to be stable, elements gain or loose electrons to get the nearrest noble gases' electronic configuration." to form an ionic hydride, it will donate one last valence ints shell, so how is nearest noble gase,helium(electronic con.= 2) is reached. but this is not like that. why? pls explain

							
Dear student,
The combinations of hydrogen with metals, which have low  electronegativity values and are electropositive with respect to  hydrogen, form ionic hydrides. Elements of group IA (alkali metals),  group IIA (alkaline Earth metals with the exception of Be and Mg) and  lanthanum form these compounds when the transfer of electrons from  metals to hydrogen atom takes place. The hydrogen atom exists as
H- ion. For example, lithium hydride (Li+H-), calcium hydride (Ca2+H2-), sodium hydride (Na+H-), etc.
Ionic hydrides are prepared by the direct combination of the metals with hydrogen at high temperatures of 750oC.
 



















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