Chemistry of the Heaviest Elements- One Atom at a Time

Abstract

In keeping with the goal of the Viewpoint series of the Journal of Chemical Education, this article gives a 75-year perspective of the chemistry of the heaviest elements, including a 50-year retrospective view of past developments, a summary of current research achievements and applications, and some predictions about exciting, new developments that might be envisioned within the next 25 years. A historical perspective of the importance of chemical separations in the discoveries of the transuranium elements from neptunium (Z = 93) through mendelevium (Z = 101) is given. The development of techniques for studying the chemical properties of mendelevium and still heavier elements on the basis of measuring the radioactive decay of a single atom ("atom-at-a-time" chemistry) and combining the results of many separate experiments is reviewed. The influence of relativistic effects (expected to increase as Z2) on chemical properties is discussed. The results from recent atom-at-a-time studies of the chemistry of the heaviest elements through seaborgium (Z = 106) are summarized and show that their properties cannot be readily predicted based on simple extrapolation from the properties of their lighter homologues in the periodic table. The prospects for extending chemical studies to still heavier elements than seaborgium are considered and appear promising. Included as supplemental material is a collection of videos from the E. O. Lawrence Berkeley National Laboratory, based on interviews with nuclear chemists who have discovered and studied the heaviest elements. Those researchers involved with the segments about Lawrencium include Robert Silva, Torbjorn Sikkeland, Matti Nurmia, Robert Latimer, and Albert Ghiorso, all of whom are from the Lawrence Berkeley Laboratory.