Volume 91, Issue 12 - Mendeleev-150 / The 4th International Conference on the Periodic Table 26–28 July 2019 – ITMO University, Saint Petersburg (Russia)

The conference Mendeleev 150 was held to join the worldwide celebrations of the 150 th Anniversary of the publication of Dmitri I. Mendeleev’s Periodic Table of Chemical Elements and the International Year of the Periodic Table proclaimed by the United Nations. The presentations of the invited speakers were published by the Journal of Pure and Applied Chemistry as a special issue. The papers in this issue formed a broad picture of the Periodic Table: the history, the people, the reasoning, the mathematical description of the law, and the efforts to predict and to create any new elements. The highlights of the presentations are briefly introduced in this article as the Preface to the special issue.

Between his initial proposal in February 1869 and his final table of November 1870, Mendeleev made radical improvements, linking his groups to highest oxidation states, clarifying the relationship of element and substance, and making detailed predictions of the properties of three missing elements. However, his inflexible belief in an alternating structure of rows of VII and VIII groups made it impossible for him to include the ‘rare earths’, and the relationship between the two rows of VII at the top confused the system. From 1873 onwards, other interests prevented him from thinking about his table, apart from accommodating the noble gases. His final table of 1906 shows no significant advance on that of 1870, and indeed, the top row contains absurd guesses about elements around hydrogen.

The history of chemistry has not once seen representations of the periodic system that have not received proper attention or recognition. The present paper is dedicated to a nearly unknown version of the periodic table published on the occasion of the centenary celebration of Mendeleev’s birth (1934) by V. Romanoff. His periodic table visually merges Werner’s and Janet’s periodic tables and it is essentially the spiral periodic system on a plane. In his 1934 paper, Romanoff was the first one to introduce the idea of the actinide series, a decade before Glenn T. Seaborg, the renowned creator of the actinide concept. As a consequence, another most outstanding thing about Romanoff’s paper occurs towards its very end: he essentially predicted the discovery of elements #106, #111 and #118. He theorized that, had uranium not been the “creative limit”, we would have met element #106, a “legal” member of group 6, element #111, a precious metal, “super-gold” and element #118, a noble gas. In 2019, we take it for granted that elements #106, #111 and #118 indeed exist and they are best known as seaborgium, roentgenium and oganesson. It is fair to say that Romanoff’s success with the prediction of correct placement and chemical properties of seaborgium, roentgenium and oganesson was only made possible due to the introduction of an early version of the actinide series that only had four elements at that time. Sadly, while Professor Romanoff was imprisoned (1938–1943), two new elements, neptunium (element #93) and plutonium (element #94) were discovered. While Professor Romanoff was in exile in Ufa (1943–1953), six further elements were added to the periodic table: americium (element #95), curium (element #96), berkelium (element #97), californium (element #98), einsteinium (element #99) and fermium (element #100). The next year after his death, in 1955, mendelevium (element #101), was discovered. Romanoff’s version of the periodic table is an unparalleled precursor to the contemporary periodic table, and is an example of extraordinary anticipation of the discovery of new chemical elements.

Glenn Seaborg was born on Michigan’s Upper Peninsula in 1912. At age 10, he moved to southern California, where his high school chemistry and physics teacher, Dwight Logan Read, sparked his interest in these fields. Seaborg was the first person to have an element named after him while he was still living. The only other person to have an element named after him while he was still alive was Yuri Oganessian.

A comparison between the figures of Levi and Mendeleev is proposed, based on their peculiar ways of conceiving their professional role of chemist, their life experiences, their achievements and their thought. The Weltanschauung of these two figures, despite their having lived in distinct historical periods and their belonging to distinct cultures, was deeply influenced by the fact of being chemists: chemistry was – for both of them – a tool for interpreting the world around them and acting effectively in it. The chemistry Levi talks about in his writings is not just a narrative pretext: it is part of his vision of the world and a means of survival in the hellish context of the extermination camp. Similarly, Mendeleev’s idea of chemistry was always related to the life context and the human condition: this explains his pedagogical concerns and the attention payed to social, economic and cultural issues typical of his time. Both Levi and Mendeleev were chemists for whom chemistry was a means of civil engagement. Their writings show that chemistry was a source of inspiration for their ethics.

Discovery of new element has been an impossible dream for Japanese people for over 100 years. Finally, in 2017, nihonium earned a permanent seat on Mendeleev’s Periodic Table. The history of search for new elements in Japan is described here together with our challenges on the cosmological history of element genesis in the universe.

After a compact history of the PT, from Döbereiner’s triads to the theoretical predictions up to element 172, a number of particular issues is discussed: Why may Z  = 172 be a limit for stable electron shells? What are the expected stability limits of the nuclear isotopes? When are formally empty atomic orbitals used in molecular electronic structures? What is ‘Secondary Periodicity’? When do the elements (Ir, Pt, Au), at the end of a bond, simulate (N, O, I), respectively? Some new suggestions for alternative PTs are commented upon. As a local connection, Johan Gadolin’s 1794 analysis of the Ytterby mineral is mentioned.

The Periodic Law, one of the great discoveries in human history, is magnificent in the art of chemistry. Different arrangements of chemical elements in differently shaped Periodic Tables serve for different purposes. “Can this Periodic Table be derived from quantum chemistry or physics?” can only be answered positively, if the internal structure of the Periodic Table is explicitly connected to facts and data from chemistry. Quantum chemical rationalization of such a Periodic Tables is achieved by explaining the details of energies and radii of atomic core and valence orbitals in the leading electron configurations of chemically bonded atoms. The coarse horizontal pseudo-periodicity in seven rows of 2, 8, 8, 18, 18, 32, 32 members is triggered by the low energy of and large gap above the 1s and n sp valence shells (2 ≤  n  ≤ 6 !). The pseudo-periodicity, in particular the wavy variation of the elemental properties in the four longer rows, is due to the different behaviors of the s and p vs. d and f pairs of atomic valence shells along the ordered array of elements. The so-called secondary or vertical periodicity is related to pseudo-periodic changes of the atomic core shells. The Periodic Law of the naturally given System of Elements describes the trends of the many chemical properties displayed inside the Chemical Periodic Tables. While the general physical laws of quantum mechanics form a simple network, their application to the unlimited field of chemical materials under ambient ‘human’ conditions results in a complex and somewhat accidental structure inside the Table that fits to some more or less symmetric outer shape. Periodic Tables designed after some creative concept for the overall appearance are of interest in non-chemical fields of wisdom and art.

It possible to view the periodic table as a portrayal of various aspects of symmetry and its breaking. This article does not add anything new to our understanding of the table, but explores its foundations in a different way from the conventional approach.

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.

Review of attempts to generalize the principle of periodic system to objects other than chemical elements in some areas of natural science, particularly in physics, molecular science and biology.

By decision of the UN General Assembly 2019 was declared an International Year of the Periodic Table of Chemical Elements. On this occasion, in Bulgaria, an anniversary postage stamp was issued. Search for a link between the properties of the chemical elements and their atomic weight was undertaken before Mendeleev by many chemists. It is characteristic of all these classifications that the observed proximity in the properties of the elements has been attributed to chance. Mendeleev, however, was the only one who perceived that beyond the periodicity of the elements’ properties there is an important natural law. With the discovery of the structure of atoms, the periodic table of chemical elements found its scientific explanation. The periodic table set an important task to chemistry – to look for the relationship between the composition and the properties of the substances, including the disclosure of the regularities which are the basis of the so-called “anomalies”.

This article seeks to encourage the adoption of modern methods of surface analysis in teaching contexts by introducing the use of attenuated total reflection infrared spectroscopy (ATRIRS) in analysis of adsorption reactions at hydrous metal oxide thin films. The first experiment shows how outer-sphere adsorption of perchlorate ion is distinguished from inner-sphere adsorption of ethanedioate (oxalate) ion at TiO 2 surfaces. The second experiment shows how the nature of adsorption of sulfate ion to iron oxide surfaces changes with pH. In the third experiment, the variation of the amount of benzene-1,2-diol (catechol) adsorbed to TiO 2 with solution concentration enables an adsorption constant to be derived from the adsorption isotherm.