The Periodic Table: Key to Past "Elemental" Discoveries—A New Role in the Future?

Abstract

The latest information on the chemical periodic table and the confirmation and naming process for new elements are discussed. The name roentgenium (Rg) for element 111 was officially accepted in 2004. Discovery of element 112 was confirmed in May 2009, but the naming process is just beginning. This year marks the 140th anniversary of Mendeleev's table showing periodicity in chemical properties of known elements arranged in order of their atomic weights. Its success in prediction of new or “missing” elements and their properties are discussed. The role of later periodic tables based on atomic number in facilitating or sometimes even “inhibiting” the discovery of new elements is reviewed and several versions of the periodic table are shown. Results of “one atom-at-a-time” chemical studies of the transactinide elements from rutherfordium (104) through hassium (108) are briefly summarized. New techniques and instrumentation for performing more detailed chemical studies and extending investigations to heavier elements are considered. These studies depend upon producing isotopes of heavier elements with half-lives of seconds and production rates that permit obtaining statistically significant results. What, if any, will be the future role of the chemical periodic table as we go to higher atomic numbers, e. g., beyond element 118 and into a predicted “Superactinide Series” where relativistic effects may “scramble” chemical properties? Chemical and nuclear theorists will need to interact synergistically in order to explore these frontiers at the limits of both the chemical periodic table and the chart of the nuclides.