The Periodic Table of Elements is a foundational document in science, charting the known building blocks of all matter. It is not static, but an ever-expanding arrangement as researchers continue to probe the limits of nuclear physics. Elements heavier than uranium (92 protons) do not occur naturally on Earth because their nuclei are unstable. These elements must be artificially created in laboratories through highly specialized methods.
Identifying the Most Recent Addition
The most recent element to receive an official name and symbol, thereby completing the seventh period of the Periodic Table, is Oganesson. Oganesson, represented by the chemical symbol Og, has the atomic number 118 (118 protons). The official name and symbol were approved by the International Union of Pure and Applied Chemistry (IUPAC) in November 2016.
The element was named in honor of the Russian nuclear physicist Yuri Oganessian for his pioneering contributions to the field. Oganesson was discovered through a collaboration between scientists at the Joint Institute for Nuclear Research in Dubna, Russia, and the Lawrence Livermore National Laboratory in the United States. It occupies the final position in the noble gas column, though its chemical properties are still largely theoretical due to its extreme instability.
The Process of Element Synthesis
Elements like Oganesson are not found in nature and must be synthesized one atom at a time using nuclear reactions. This creation process relies on powerful particle accelerators to overcome the strong repulsive force between the positively charged nuclei. Researchers accelerate ions of a lighter element to nearly a tenth of the speed of light.
The goal is to achieve nuclear fusion, where the two colliding nuclei merge to form a single, heavier nucleus. The reaction that produced Oganesson, for example, involved bombarding a target of Californium-249 with a beam of Calcium-48 ions. The probability of the two nuclei fusing instead of simply breaking apart is extremely low, making the experiments very inefficient.
The Official Confirmation and Naming Process
Before a synthesized element is formally added to the Periodic Table, its discovery must be rigorously verified by international bodies. The Joint Working Group of IUPAC and the International Union of Pure and Applied Physics (IUPAP) is responsible for examining the evidence and confirming the claim of discovery. This process can take several years, often requiring independent laboratories to replicate the original synthesis.
Once the discovery is confirmed, the credited research team is invited to propose a permanent name and symbol to the IUPAC Inorganic Chemistry Division. Naming conventions dictate that an element can be named after a mythological concept, a mineral, a place or country, a property of the element, or a scientist. New elements are also assigned specific endings to maintain historical and chemical consistency.
Properties of Superheavy Elements
Superheavy elements are characterized by their extreme instability and rapid radioactive decay. Oganesson, like many other synthetic elements, has an incredibly short half-life. The most stable known isotope of Oganesson, Oganesson-294, has a half-life measured in milliseconds.
This fleeting existence makes it nearly impossible to study the element’s chemical properties directly in any bulk quantity. Despite the general trend of increasing instability with higher atomic number, nuclear theory predicts the existence of an “Island of Stability.” This is a theoretical region of superheavy elements expected to have a much longer half-life due to a favorable number of protons and neutrons, potentially measured in minutes or even days. Researchers continue to explore this region, hoping to synthesize a heavier element stable enough for more detailed study.