Tennessine

Tennessine. It is a synthetic, superheavy element in the periodic table with the atomic number 117. The element is highly radioactive and unstable, with all its known isotopes having very short half-lives. Its creation and study represent a significant frontier in nuclear physics and the exploration of the so-called "island of stability."

Properties

The predicted physical properties of tennessine are largely theoretical due to its extreme instability and minute production quantities. It is expected to be a solid under standard conditions, potentially exhibiting a metallic appearance, though its rapid radioactive decay prevents direct observation. Calculations suggest it may have a high density, comparable to other superheavy elements like oganesson and livermorium. Its placement in the periodic table within the halogen group implies it might share some periodic trends, but strong relativistic effects on its electrons are predicted to dominate its chemical behavior, making it likely distinct from lighter congeners like astatine and iodine.

History

The discovery of tennessine was a collaborative effort announced in 2010 by a joint team of Russian and American scientists. The pivotal experiments were conducted at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, utilizing the heavy-ion accelerator at the Flerov Laboratory of Nuclear Reactions. The American contribution, which provided the critical target material berkelium-249, came from the Oak Ridge National Laboratory in Tennessee, a fact honored in the element's name. The discovery was independently verified by the International Union of Pure and Applied Chemistry (IUPAC) in 2015, which credited the collaboration between JINR, Oak Ridge National Laboratory, Lawrence Livermore National Laboratory, and Vanderbilt University. The name "tennessine" was formally adopted by IUPAC in 2016.

Production and synthesis

Tennessine is produced artificially in particle accelerators via nuclear fusion reactions. The primary synthesis method involves bombarding a target of berkelium-249 with accelerated ions of calcium-48. This fusion-evaporation reaction results in the formation of a compound nucleus of tennessine, which then almost instantly decays by emitting alpha particles. These experiments are exceptionally challenging due to the scarcity of berkelium-249, which must be produced in specialized reactors like the High Flux Isotope Reactor at Oak Ridge, and the extremely low production cross-sections, yielding only a few atoms over extended periods of beam time. All production has occurred at the Flerov Laboratory of Nuclear Reactions in Dubna.

Chemical characteristics

As a member of group 17 of the periodic table, tennessine is classified as a halogen, but its chemistry is predicted to be anomalous. Strong relativistic effects contract its 7s and 7p electron orbitals, significantly influencing its potential oxidation states and bonding. Theoretical studies, often using advanced computational methods like density functional theory, suggest it may exhibit a stable +1 oxidation state, unlike the typical -1 state of lighter halogens, and could even show some metallic character. Its predicted reactivity with gold or platinum surfaces is a subject of computational investigation, though experimental verification remains a formidable challenge due to the element's fleeting existence.

Isotopes

Several isotopes of tennessine have been identified, all radioactive and synthetic. The most studied include tennessine-293 and tennessine-294, with half-lives on the order of tens to hundreds of milliseconds. These isotopes decay primarily via alpha decay into isotopes of moscovium. The synthesis and decay chains of these atoms provide critical data for testing nuclear models, such as those predicting the "island of stability" around heavier, potentially longer-lived isotopes like tennessine-297. The study of these decay properties is crucial for validating theoretical predictions from institutions like the Lawrence Livermore National Laboratory and advancing our understanding of superheavy nuclei.

Applications and research

Currently, tennessine has no practical applications outside of fundamental scientific research. Its primary value lies in expanding the boundaries of the periodic table and testing the limits of nuclear theory. Research focuses on confirming its chemical properties, which could challenge traditional periodic trends, and on the quest to synthesize heavier isotopes that might reside closer to the predicted "island of stability." These studies involve international collaborations like those at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt and future facilities like the Facility for Rare Isotope Beams (FRIB). The work also contributes to broader fields such as nuclear astrophysics and the understanding of nucleosynthesis in stellar environments.

Category:Chemical elements Category:Synthetic elements Category:Halogens