February 13, 2024

Exploring the Quest for the Limit of the Periodic Table

Since the turn of the century, six new chemical elements have been discovered and subsequently added to the periodic table of elements, the very icon of chemistry. These new elements have high atomic numbers up to 118 and are significantly heavier than uranium, the element with the highest atomic number (92) found in larger quantities on Earth.

This raises the following questions: How many more of these superheavy species are waiting to be discovered? Where—if at all—is a fundamental limit in the creation of these elements? And what are the characteristics of the so-called island of enhanced stability?

In a recent review, experts in theoretical and experimental chemistry and physics of the heaviest elements and their nuclei summarize the major challenges and offer a fresh view on new superheavy elements and the limit of the periodic table.

Professor Christoph Düllmann from the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Johannes Gutenberg University Mainz, and the Helmholtz Institute Mainz (HIM) is one of the experts contributing to this review. In its February issue, Nature Review Physics presents the topic as its cover story.

Visualizing an island of stability of superheavy nuclei

Already in the first half of the last century, researchers realized that the mass of atomic nuclei is smaller than the total mass of their proton and neutron constituents. This difference in mass is responsible for the binding energy of the nuclei. Certain numbers of neutrons and protons lead to stronger binding and are referred to as ‘magic.’

Early theoretical predictions suggested that the extra stability from the next ‘magic’ numbers, far from nuclei known at that time, might lead to lifetimes comparable to the age of the Earth. This led to the notion of a so-called island of stability of superheavy nuclei separated from uranium and its neighbors by a sea of instability.

There are numerous graphical representations of the island of stability, depicting it as a distant island. Many decades have passed since this image emerged, s