12.2 The elementary substances 12.2.1 The properties of the elementary substances 1.Physical properties ☆Metallic luster; ☆Low densities;. ☆Soft; ☆Low melting point; *Good conductor of heat and electricity Na Li K §12.2.1 The properties of the elementary substances Na Li K 1.Physical properties §12.2 The elementary substances ☆Metallic luster; ☆Low densities; ☆Soft; ☆Low melting point; ☆Good conductor of heat and electricity