Chemical descriptors using DFT concepts characterize elements reactivity. Hardness and electrophilicity relate to the charge and energy exchanged, determining changes in the length and slope during reaction. Three zones are identified. At low charge exchange (<0.25) the length of the path shortens with constant slope. At higher charge exchange (>0.50) the length increases while its slope rotates. The two regions respectively correspond to frontier molecular orbital and charge-controlled reactions. They relate to the divergence and rotational components of the chemical potential gradient, pointing toward nucleophilic or electrophilic reactions. In between reactions are a mixing both end-member components. (C) 2018 Elsevier B.V. All rights reserved.