What do you understand by the term 'non-stoichiometric hydrides'? Do you expect this type of the hydrides to be formed by alkali metals? Justify your answer.

Explanation

Alkali metals do not form non-stoichiometric hydrides. Since alkali metals are highly reducing , they transfer their valence shell electron to the hydrogen atom, thereby forming `H^(ө)` ion. Thus alkali metal hydrides are ionic, in which `H^(ө)` ions occupy holes in the metal lattice. Since there is complete transfer of an electron from alkali metal atom to hydrogen atom, the ratio of metal to hydrogen is integral and hydride formed is stoichiometric hydrides.