Periodic law: new formulation and equation description

Abstract

Abstract The atomic weight, nuclear charge, electron configuration of an atom and the total number of i-electrons in an atom belonging to i-block (i = s, or p, or d, or f) are considered as the fundamental characteristics of an element (atom). Only in the latter case, the true periodicity is achieved: the repetitions occur at regular intervals. The total number of i-electrons in an atom belonging to i-block is used as the new basis for the description of the periodicity. This made possible to propose a new formulation of the Periodic law and to describe the Periodic law by an equation. The equation provides opportunities for large-scale prediction of the properties of elements and their compounds; it does not require special knowledge to work with it. Theoretical and applied aspects of the application of the new formulation and equation are outlined. Predictions are made for proton affinity and gas phase basicity of 20 elements, constants of inductive effects of 185 atoms and groups, electronic parameters of 222 neutral ligands. The suitability of the equation is exemplified by the description of the properties of atoms and elements, such as ionization energy, electron affinity, proton affinity, electronegativity, covalent atomic radii and the enthalpy of element formations in the gas phase. The equation makes possible to describe also the properties of compounds and their fragments: the acidic properties of the hydrogen compounds of the elements, the acidic properties of protonated atoms and molecules, gas phase basicity and proton affinity of compounds, inductive effects of ligands in coordination chemistry and substituents in organic chemistry, electronic parameters of neutral ligands, the electron effect constants of coordinating metals.