Melting Points of Sodium and Potassium

Sodium (Na), has a small atomic radius hence stronger metallic bonds than potassium (K). The larger atomic size in potassium results in weaker metallic bonds between its atoms compared to the smaller and more closely packed sodium atoms, which leads to a lower melting point for potassium.

Explanation

The melting point of an element is influenced by its atomic structure and the forces that hold its atoms together. In the case of sodium (Na) and potassium (K), both are alkali metals belonging to Group 1 of the periodic table, which means they have similar chemical properties and electronic configurations in their outermost energy level.