Sodium (Na) and Potassium (K);
Sodium (Na) is a metal. So, sodium readily reacts with a halogen like chlorine (Cl) to form an ionic chloride called sodium chloride. This is illustrated below:
Ionic bond; Ionic compounds .
Physical properties of ionic compounds:
(i) Ionic comp ounds are usually hard, brittle.
(ii) They conduct electricity when molten or dissolved.
(iii) They have high melting and boiling points.
(iv) Most are soluble in polar solvents such as water.