Question

Halides of alkali metals are high melting solids.Explain

Answer 1

Generally the halides of alkali metals are ionic in nature. They have high melting point because of the strong electrostatic attraction (ionic bond) between cations and anions. It takes a lot of energy to overcome this attraction so that ions can move freely. For example : Sodium chloride (NaCl) is an ionic compound and each sodium ion (Na+ ) interacts with six chloride ions (Cl-) ions on each side of it and each Cl- interacts with six Na+ around it. This forms a strong electrostatic attractions between Na+ and Cl-ions and requires a lot of energy to overcome them . The melting point of NaCl is 801°C.