The conversion of the liquid to the vapor below boiling temperature of liquid is called evaporation.
Each molecule in liquid phase is attracted to other molecules in liquid by the intermolcular forces of attraction. When the process of evaporation starts, the molecules has to change the phase from the liquid to vapor for which they have to break all these interaction so that they can escape. The molecules with sufficient energy to do so only can do this. These molecules with high energy leave and remaining molecules are ones which did not have the enough energy to evaporate. Thus, average kinetic energy of molecules in liquid left behind is lower than it was before. <u>So, evaporation is a cooling process because heat of the molecules was used up for breaking hotter molecules out into gas phase and the left ones are cooled.
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Those that “prefer” A charge; the Halogens and Chalcogens are good examples - Halogen MEANS salt forming, and even organic compounds can form salts; look up “tropylium ion”.
