Why boiling point of calcium is higher than potassium?

The boiling point of calcium is higher than that of potassium due to differences in their atomic structure and bonding. Calcium, a group 2 alkaline earth metal, has a stronger metallic bond compared to potassium, a group 1 alkali metal. This is because calcium's larger atomic radius and higher charge density lead to stronger electrostatic interactions among its atoms. Consequently, more energy is required to break these bonds in calcium, resulting in a higher boiling point.