Thermodynamic conditions of the adsorption of gaseous molecules on metals are discussed in this work. The equilibria of the formation of surface arrays comprising several atoms, the formation of ordered structures, and the dissolution of gas atoms in the metal have been reviewed. It was found that the heat and the free energy of chemisorption is affected by the change in the number and energy of bonds between metal atoms and the adsorbate in the structures being formed. It was pointed out that the change in the interactions between the surface metal atoms before and after the adsorption must be followed by an energetic effect that would affect the chemisorption energy.