Page 3 - Microsoft Word - Module-1

Reactivity towards halogen: Alkali metals form ionic

halides. But Li form covalent halide.

Reducing nature: Alkali metals are strong reducing

agents.

Solutions of alkali metals in liquid NH : They are
3
dissolved in liquid NH to form blue solution due to
3
presence of ammoniated electron. The blue solution is

paramagnetic due to presence of unpaired electrons.

+
M + (x+y) NH → [M (NH ) ] +[e(NH ) ]
+
3
3 x
3 y
In concentrated solution the blue colour changes to
bronze and becomes diamagnetic.

USES OF ALKALI METALS

 Li is used to make alloy with Pb to make white metal

bearings for motor engines

 With Al to make aircraft parts.

 Liquid Na is used as coolant.

 KCl is used as fertilizer and KOH is used in the

manufacture of soft soap.

 Cs is used in photoelectric cells.