12.1 The elementary substances 12.1.1 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 §12.1.1 Properties of the elementary substances Na Li K 1.Physical properties §12.1 The elementary substances ☆Metallic luster; ☆Low densities; ☆Soft; ☆Low melting point; ☆Good conductor of heat and electricity