This article discusses the mathematizing of the chemical periodic system as a grid, which leads to a quadratic function or “binódica function” formed by pairs of periods or binodos. We describe the periodic law as an increasing function of the principal quantum number. It works subject to the dialectical laws that generate; first: gradual quantitative changes:, with “duplication” of periods:. Second: radical quantitative changes:, with the emergence of new quantum transitions, growth and a change in the format of the binodos. (...) We use analytical and graphic methods to mathematize Mendeleev’s law, making the size of the binodos and the continuous series depend on the number of the binode, which is the same quantum number. Likewise, we show a graphic representation, in 2D, of a continuous and self-similar spiral function of the elements, in a geometric growth pattern. (shrink)

Demarcation of elements for two subsets appears to be the most fundamental approach to their classification. If one draws a vertical straight line through the middle of each block of elements in the Periodic table, all the elements are divided into two subsets: “early” and “later”. For example, in the d-block, the early ones are Sc–Mn, and the late ones, respectively, are Fe–Zn. Later elements partially repeat the properties of the early ones, and this is defined as the internal periodicity. (...) Another criterion for dividing the elements into two subsets is the evenness and oddness of the sum of n + l, where n is the principal quantum number, and l is the orbital quantum number for the outer electron subshells. Properties of the odd elements are closer to each other than to properties of even elements, and vice versa. This regularity is manifested as the secondary periodicity. The history of concepts, which considered the existence of subsets as well as of inner and secondary periodicities, is discussed. The features of the electronic structure, which underlie the existence of subsets, are considered. The existence of subsets was depicted earlier by dividing the periodic table into two tables or by applying a mirror-symmetric table. Small changes are proposed in the conventional Periodic table, allowing to reflect the existence of the considered subsets. (shrink)