Question

Why do alkali metals have low melting and boiling points?​

Answer 1

Explanation:

The decrease in melting and boiling points down the group can be explained by the additional shell being added to the previous element causing the atomic radius to increase. The increasing atomic radius means weaker forces between the atoms and so a lower melting and boiling point. Alkali Metals are soft

Answer 2

Alkali metals have low binding energy in the metal crystal lattice as these atoms have only one valence electron. This results in the formation of metallic bonds which are not very strong. Also, alkali metals melting and boiling points decrease down the group.