Atmospheric structure and heating rate obtained from isolating the impacts of Fe and Mg ions. Top: temperature (left) and total heating rate (right) as a function of pressure obtained accounting for all elements (black; same as in Figs. 2 and 5), considering that in the planetary atmosphere Fe exists only in the form of FeI (blue), only in the form of FeII (green), or is absent (i.e. no Fe; same as Fig. 5; red). Bottom: same as the top, but for Mg.