Properties of hydrides of Group I:
(i) All the alkali metal hydrides are ionic solids with high melting points. Ionic character increases from Li H to CsH.
(ii) These hydrides are strong reducing agents and their reducing character increases on moving down the group.
(iii) On moving down the group, atomic size increases and M-H bond strength in hydrides decreases so, thermal stability of hydrides decreases.
Properties of hydrides of Group II:
(i) BeH2 and MgH2 are electron deficient covalent compounds. They have polymeric structure due to electron deficiency.
(ii) CaH2 and SrH2 are ionic in nature.
(iii) Hydrides of alkaline earth metals react with water to librate hydrogen gas. So, they actions as reducing agents.
Structure of Beryllium Hydride :
Beryllium hydride (BeH2) is electron deficient covalent compound. It has polymeric structure. It has three-centre two-electron bond with chemical formula (BeH2)n.
