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.
1. The hydrides in which the ratio of the metal and hydrogen is found to be fractional are called non-stoichiometric hydrides. It is also observed that this fractional ratio is not fixed but varies with the temperature and pressure.
2. Non-stoichiometric hydrides is generally formed by d and f block elements as in these hydrides, the hydrogen atoms occupy some of the holes in the lattice of the metal and also all the holes are not occupied.
3. Alkali Metal react with hydrogen to form an ionic compound that is alkali metal form ionic bonds with hydrogen and alkali metal donate electron to hydrogen atom and hydrogen thus exists as electronegative element in the hydride.