Compounds of Alkali metals
Alkali metals are highly reactive. After exposure to air or O2, they get tarnished quickly due to the formation of a film of oxides on their surface. In order to protect them from O2 or air, the metals are put into kerosene oil or paraffin oil. Oxides are also formed when they are burnt in air or oxygen, In this respect reactions of lithium and sodium are different. Li forms monoxide whereas Na forms peroxide.
2. Hydrides :
The metal hydrides of heavier metals are formed by reducing their carbonates in a current of H2 gas.
Lithium hydride (LH) is stable in dry air up to red heat and sodium hydride (NaH) is inflammable in the presence of O2 at 277∘. Whereas potassium hydride (KH) is inflammable at room temperature. All the hydrides are decomposable except LiH. On exposure to light, they turn blue without decomposition.
All the hydrides are ionic M+H−. They form non-directional bonds between M+and H−hence they have no geometry. All have face-centered cubic lattices.
3. Halides :
Hydrolysis: Lithium halides undergo hydrolysis to some extent in hot water but other alkali metal halides do not undergo hydrolysis.