LAUSR

Abstract Groups of electrons, radial with respect to the atomic nucleus and with the same value of the orbital quantum number and the same number on the subshell, are considered. A spin-orbital exclusion principle is established, regulating the spin value distribution on the subshells with the same value of the orbital number. According to this principle, all subshells are divided into positive and negative ones, depending on the direction of the spin of their first electron. It is found that, in the real sequence of the appearance of new subshells, a spin-orbital periodicity takes place, which develops in cycles consisting of two periods that are mirror-symmetric to each other in the direction of the spin of their electrons. Moreover, atomic number of any period is equal to the sum of the principal and orbital quantum numbers of its subshells, and this can serve as an explanation for the Madelung rule. It is demonstrated that Mendeleev’s chemical periodicity lags behind the spin-orbital periodicity by two elements and repeats its structure. From these positions, the absence of a pair in the first period of Mendeleev’s table and the pairing of all its other periods are explained. Based on the obtained results, an eight-period table of elements, the prototype of which being Janet’s left-step table, is compiled and briefly described.