The energy to change one mole of a substance from a liquid to a vapor at its boiling point is

Its enthalpy of vaporization.

Explanation:

It takes energy to overcome the intermolecular forces of attraction between the molecules in a liquid and force them into the vapour phase.

The process of moving molecules from the liquid phase into the vapour state is vaporization, so the amount of heat required is the enthalpy of vaporization (also called the heat of vaporization).

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.