(a,b,c,d)

Very dilute solutions of the metals are paramagnetic, with approximately one unpaired electron per metal atom (corresponding to one solvated electron per metal atom); this paramagnetism decreases at higher concentration because of the association of unpaired electrons of opposite spins.

According to the cavity concept, they occupy far greater volume than that expected from the sum of the volumes of metal and solvent and, therefore, these dilute solutions are of much lower density than pure solvent.

Conduction is due mainly to the presence of solvated electrons. As the solutions are made more concentrated, the molar conductivity at first decreases, reaching a minimum at about 0.05 molar ; thereafter, it increases again until in saturated solutions (it is comparable to that of the metal).

Evaporation of the ammonia from solutions of alkali metals yields the metal, but with alkaline earth metals evaporation of ammonia gives hexammoniates of the metals, [M(NH 3 ) 6 ] 2+ .