The alkali metals have the interesting property of dissolving in
some non-aqueous solvents, notably liquid ammonia, to give clear
coloured solutions which are excellent reducing agents and are
often used as such in organic chemistry. Sodium (for example) forms
an intensely blue solution in liquid ammonia and here the outer (3s)
electron of each sodium atom is believed to become associated with
the solvent ammonia in some way, i.e. the system is Na+(sol vent)
+ e "(solvent).