Some solved problems of the periodic system of chemical elements

Abstract

Basic questions on the periodic system (PS) of chemical elements are still under discussion. Several common misconceptions will be resolved. The word "chemical element" comprises more than two concepts. The PS can be rationalized on a quantum chemical basis, namely with the aid of four concepts: (1) electron configurations of bonded atoms, (2) realistic sequences of orbital energies, (3) spatial extension of valence and Rydberg orbitals, and (4) energy gaps above the closed 1s 2 and np 6 shells (n ϭ 2-6). The PS of known elements cannot be naively extrapolated. The common discussion of the PS in textbooks of general, inorganic, and physical chemistry needs revision.

Recent attempts to change the periodic table

“…Quite independently of these attempts, another theoretical chemist, Eugen Schwarz, argued instead that the Madelung rule does not truly reflect the order of orbital occupation, in the way it is generally believed to do [31,32]. Schwarz's main concern was to resolve a long-standing conundrum that is familiar to every chemistry student and their instructors.…”

Formal structure of periodic system of elements

“…All rights reserved. As noted by Mendeleev: 1 'the reason for the absence of any explanation concerning the nature of the periodic law [Here, in general, periodic system] resides entirely in the fact that not a single rigorous, abstract expression of the law has been discovered (p. 221 of [21]). ' In this paper, we report a formal structure for periodic system, based on a contemporary mathematical interpretation of 1869 Mendeleev publication and recent studies of the system.…”

“…Since the formulation of the periodic system in the 1860s, the quest for understanding its structure has intensively motivated research in different areas of chemistry and physics. However, almost 150 years after its announcement, the different approaches from quantum chemistry [1,2,3,4,5,6,7,8,9,10,11], group theory [12,13], clustering [11,14,15] and information theory [16,10], to name but a few [17,18], have not led to an unified picture [19]. Instead, they give insights on the possible chemical and physical causes of the patterns depicted by the system but have failed in providing a formal structure for it [19].…”