150th Anniversary of the Periodic Table of the Chemical Elements

Abstract

The year 2019 was proclaimed by the UN and UNESCO as the International Year of the Periodic Table of the Chemical Elements; by its beginning, the seventh period of the Table was already filled with new, very heavy elements. According to theoretical predictions, isotopes of superheavy elements with increased stability form a large zone in the form of an island with a vertex located near the “magic” numbers of protons Z = 114 and neutrons N = 184 on the nuclide map. New elements with atomic numbers from 114 to 118 were synthesized in the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research (JINR, Dubna), in 2000–2012 by fusion reactions of target nuclei (heavy actinide isotopes (Z = 94–98)) with bombarding 48Ca ions. The experimental results suggest that there may exist nuclei or elements with atomic numbers greater than 118 and mass greater than 300 amu. A new experimental complex, the Factory of Superheavy Elements (SHEF), was created in Dubna to study the nuclear and electronic structures of new elements and their chemical properties and to synthesize elements from the beginning of the eighth period of the Periodic Table. A new DC-280 accelerator has already been launched in the SHEF, and experiments are planned to begin. The introductory and final parts of my speech at the scientific session of the General Meeting of the Members of the Russian Academy of Sciences are related to the discovery of the Periodic Law published by D.I. Mendeleev 150 years ago. The action of this law in the properties of the heaviest elements represents today one of the most urgent and interesting problems of the natural sciences.