DERIVATION OF IONIZATION ENERGY an‎d ELECTRON AFFINITY EQUATIONS USING CHEMICAL HARDNESS an‎d ABSOLUTE ELECTRONEGATIVITY IN ISOELECTRONIC SERIES

Chemical hardness (?) and absolute electronegativity (?) have important applications in chemistry. In the conceptual Density Functional theory (DFT), these concepts has been associated with electronic energy and the relationship with ionization energy (I) and electron affinity (A) of these concepts has been given. In this study, graphical method was used in order to see the relationship with the atomic number (Z) of chemical hardness and absolute electronegativity in isoelectronic series. These series was considered because all members of an isoelectronic series have the same shielding constant. Chemical hardness and electronegativity equations depending on atomic number were obtained from graphs of ?=f (Z) and ?=f (Z) for isoelectronic series that contain electron from 1 to 20. Ionization energy and electron affinity equations were obtained making use from the chemical hardness and electronegativity equations. In the last stage, the relationship with the number of electron of coefficients in the ionization energy and electron affinity equations was examined. As a result, new equations consistent with experimental results that depending on atomic number and number of electron were obtained.