The search for Element 119 represents the current frontier of the periodic table, pushing the limits of nuclear physics and chemistry. This hypothetical substance is the lightest element not yet successfully synthesized and confirmed. Element 119 is classified as a superheavy element, possessing an atomic number greater than 103. Its atomic number of 119 means its nucleus contains 119 protons, and its discovery would mark the beginning of the theoretical eighth period.
Defining the Superheavy Element
Because Element 119 has yet to be created and formally recognized, it carries the temporary systematic name Ununennium, derived from the Latin terms for its atomic number (one-one-nine). The temporary chemical symbol assigned by the International Union of Pure and Applied Chemistry (IUPAC) is Uue. This placeholder nomenclature is used until the element’s discovery is confirmed and a permanent name is chosen.
The discovery and naming process for a new element is rigorous, requiring confirmation from IUPAC and the International Union of Pure and Applied Physics (IUPAP). Scientists must provide conclusive evidence that the observed decay chains are unique to the superheavy nucleus they claim to have created. Once a discovery claim is accepted, the discovering institution proposes a permanent name and symbol for the element.
Element 119 would be the first to occupy the eighth period of the periodic table, extending the table beyond the last confirmed element, Oganesson (Element 118). The synthesis of a new period-starting element is a significant milestone. It allows researchers to test theoretical models that predict the behavior of matter at these extreme atomic weights. Discovering this new element would validate the periodic table’s structure in a region where nuclear forces and electron behavior become unpredictable.
The Fusion Reactions Required for Creation
Synthesizing superheavy elements like Element 119 is achieved through nuclear fusion reactions using powerful particle accelerators. This involves accelerating a beam of lighter nuclei (the projectile) and smashing it into a target composed of heavy nuclei. For Element 119, one promising reaction involves bombarding a target of berkelium-249 (\(^{249}\)Bk) with a beam of titanium-50 (\(^{50}\)Ti).
An alternative approach pursued by laboratories like RIKEN in Japan uses a vanadium-51 (\(^{51}\)V) beam directed at a curium-248 (\(^{248}\)Cm) target. The goal of either reaction is for the projectile and target nuclei to fuse into a single compound nucleus with 119 protons. This compound nucleus must then “cool down” by expelling a few neutrons to settle into a more stable state before it fissions, a process known as hot fusion.
The main obstacle to creation is the extremely low probability of a successful fusion event, quantified by the reaction’s cross-section. Theoretical predictions suggest a cross-section in the picobarn or sub-picobarn range, meaning only one successful fusion event might occur after months of operation. Scientists at major international facilities, including RIKEN and the GSI Helmholtz Centre for Heavy Ion Research in Germany, are refining their accelerator and detection technologies to overcome this challenge. Experiments must run for many months to observe even a single atom of the new element.
Theoretical Placement and Predicted Characteristics
The periodic table predicts that Element 119 will sit directly below Francium in Group 1, classifying it as the first alkali metal of the eighth period. This placement suggests it would possess a single valence electron in its outermost shell, specifically the \(8s^1\) electron configuration. However, its behavior is expected to deviate from the lighter alkali metals due to effects arising from its immense number of protons.
For elements with such high atomic numbers, the electrons closest to the nucleus are accelerated to speeds approaching the speed of light, necessitating calculations based on the theory of relativity. These relativistic effects cause the \(s\) and \(p\) orbitals to contract, while the \(d\) and \(f\) orbitals expand, altering the electron shell structure. As a result, the outermost \(8s\) electron is held more tightly than simple periodic trends suggest, a phenomenon known as relativistic stabilization.
This stabilization is predicted to make Ununennium less reactive than Francium, giving it a higher ionization potential (the energy required to remove the outermost electron). Its chemical properties may therefore resemble lighter alkali metals like Sodium or Potassium closely than Francium. Furthermore, all superheavy elements are unstable, and Element 119 is predicted to have an extremely short half-life, possibly decaying in less than a microsecond. This instability places it outside the hypothesized “Island of Stability,” a region of neutron-rich superheavy isotopes centered around Element 114 (Flerovium) that are expected to exhibit longer half-lives.