Tennessine

Tennessine is one of the most exotic and elusive members of the periodic table: a superheavy, man-made substance whose existence stretches the limits of modern nuclear physics and chemistry. This article explores how tennessine was discovered, how scientists produce and detect it, where (and whether) it can be found, what practical or theoretical uses it serves, and several intriguing scientific questions it raises. Along the way we will touch on the facilities and methods that made its synthesis possible and the broader quest for the so-called island of stability among superheavy nuclei.

Discovery, Naming, and the Teams Behind the Element

The story of tennessine is a collaboration between international laboratories and specialized institutions. Officially assigned atomic number element 117, it was synthesized through fusion reactions performed by teams working at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, in collaboration with American partners. The experiments that led to the first reported observations combined a beam of calcium-48 ions with targets made from berkelium-249 nuclei, producing a few atoms of new, heavy nuclei that were identified by their decay chains.

In 2016 the element was named tennessine in recognition of the significant contributions from institutions in the state of Tennessee — notably the production and provision of berkelium targets accomplished at places such as Oak Ridge National Laboratory, along with contributions from the University of Tennessee and other partners. The formally adopted symbol is Ts.

Synthesis and Experimental Techniques

Superheavy elements like tennessine are produced atom by atom in particle accelerators using fusion reactions. A high-energy beam of one type of nucleus is directed at a thin target composed of a heavier element. The two nuclei may fuse to form a compound nucleus with a very large number of protons and neutrons; if it survives long enough to evaporate a few neutrons, a new nuclide can be formed. For tennessine the canonical reaction used a beam of calcium-48 directed at a berkelium-249 target.

Typical experimental chain and detection

• Acceleration: Ions of the lighter partner are accelerated to energies tuned to maximize fusion probability.
• Target preparation: Targets of rare actinides such as berkelium-249 are prepared in minuscule amounts and mounted in the beamline; their production and handling are elaborate and costly.
• Separation: Following fusion, the reaction products are separated from unreacted beam and other reaction byproducts by gas-filled recoil separators or electromagnetic devices.
• Detection: The separated recoils are implanted in position-sensitive silicon detectors. Subsequent alpha decays and spontaneous fissions are recorded, and decay chains are reconstructed to identify the original nuclide.

Only a handful of atoms are typically produced in an experimental run, and each identification relies on matching sequences of alpha energies and decay times to expected patterns. That scarcity makes every detected event precious and requires extreme care in statistical and systematic analysis.

Physical and Chemical Properties

Tennessine is extremely short-lived: its isotopes decay in timescales ranging from milliseconds to seconds. Because only a few atoms have ever been synthesized, bulk physical or chemical measurements are impossible with current techniques. Nevertheless, theoretical models and relativistic quantum calculations allow scientists to predict several properties.

• Position in the periodic table: Tennessine belongs to group 17, the halogens. In a classical sense it would be expected to share some characteristics with iodine and astatine.
• Electron configuration: The predicted ground-state electron configuration of tennessine places it in the 7p block, but strong relativistic effects significantly alter orbital energies and can change expected chemical behavior.
• Chemical behavior: Calculations suggest tennessine could show both halogen-like chemistry (a tendency to accept electrons) and unusual metallic or low-oxidation-state behavior due to relativistic stabilization of inner orbitals and the inert-pair effect.

Because of these relativistic influences, tennessine may not behave like a typical halogen. Some theoretical studies predict that its most stable oxidation states and reaction propensities will diverge noticeably from lighter group-17 elements, making it a valuable test case for quantum chemistry under extreme conditions.

Where Does Tennessine Occur?

Tennessine does not occur naturally in the environment in any measurable quantity. Its constituent isotopes are highly unstable and decay rapidly; thus they cannot accumulate or persist on geological timescales. Any atom of Ts produced in nature — for example, by extremely rare cosmic-ray spallation events or in supernova nucleosynthesis — would vanish long before it could be observed on Earth.

All confirmed atoms of tennessine have been produced in laboratory settings. The required precursor isotopes, such as berkelium-249, themselves must be synthesized in dedicated facilities (reactors or accelerators) and then chemically separated and fabricated into targets. The logistical chain that delivers micrograms or even nanograms of target material is itself a major scientific and engineering accomplishment.

Applications — Practical and Scientific

Because tennessine exists only in atom-by-atom quantities and decays in fractions of a second to seconds, it has no practical applications in technology, medicine, or industry. No macroscopic sample can be produced, and it cannot be used as a material component. However, its scientific value is substantial and multifaceted.

• Fundamental nuclear physics: Observations of tennessine isotopes contribute to mapping nuclear shell structure, refining models of nuclear forces, and understanding how stability changes with large proton numbers.
• Search for the island of stability: The production and characterization of superheavy nuclei, including tennessine, help determine whether there is a region of relatively long-lived nuclei at certain high proton and neutron numbers — the so-called island of stability.
• Relativistic chemistry: Ts offers a laboratory (albeit a highly constrained one) to test theoretical predictions about how electron orbitals and chemical behavior change under strong relativistic influences.
• Techniques and instrumentation: Developing the methods to synthesize and detect tennessine drives advances in accelerator technology, target chemistry, detection systems, and data analysis that have broader technological and scientific spillover.

Decay Patterns and Nuclear Relationships

The few observed isotopes of tennessine decay primarily by alpha emission, producing daughter nuclei in the region of element 115 (moscovium) and further down a chain of alpha decays or spontaneous fission events. Each decay chain observed experimentally helps confirm not only the creation of the original nucleus but also properties of the daughter nuclei; in that way, synthesis of tennessine has contributed to knowledge about several nearby superheavy elements.

Because alpha-decay energies and lifetimes depend sensitively on nuclear structure, each successful identification provides input for theoretical models and helps reduce uncertainties in predictions for yet-unknown nuclei. Researchers use such data to refine semi-empirical formulas and microscopic models of nuclear behavior.

Scientific Challenges and Safety Considerations

Producing tennessine requires overcoming multiple formidable challenges:

• Target production: Making sufficient quantities of heavy actinide targets such as berkelium-249 is difficult and expensive; it typically requires high-flux reactors and careful radiochemical processing.
• Low production cross-sections: The probability of forming a superheavy nucleus in a single beam-target collision is extremely small, so experiments require long beam times and extremely stable conditions.
• Detection sensitivity: Separating rare fusion products from backgrounds and reliably identifying single-atom events demand highly specialized separators and detectors.
• Radiation hazards: All the materials and processes involved are intensely radioactive; stringent protocols and shielding are necessary to protect personnel and the environment.

Because every atom counts, experiments operate at the forefront of both instrumentation and safety. The need to manipulate nanograms of radioactive material also places a premium on advanced radiochemistry and precious laboratory resources.

Why Tennessine Is Scientifically Interesting

Several reasons make tennessine a subject of intense interest among physicists and chemists:

• Testing nuclear models: Superheavy nuclei probe the interplay of nuclear shell effects, Coulomb repulsion among the many protons, and pairing energies. Ts sits in a region where theoretical models diverge, so observations constrain and sharpen our understanding.
• Relativistic chemistry: The strong relativistic contraction and stabilization of inner orbitals in heavy elements predict behavior that differs markedly from lighter congeners. Tennessine lets chemists push theory under extreme conditions.
• Element synthesis technology: Each attempt to produce new superheavy elements drives innovations in accelerator operation, targetry, separation, and detection; those improvements enable further discoveries.
• Connections to astrophysics: Understanding how heavy nuclei form, survive, or decay has implications for nucleosynthesis scenarios in stellar explosions and neutron-star mergers, where exotic heavy isotopes may be briefly formed.

Theoretical Predictions and Open Questions

Many theoretical questions remain open regarding tennessine and nearby superheavy nuclides:

• What are the most stable isotopes in the region, and how far toward longer half-lives does the island of stability extend?
• How do relativistic effects alter chemical bonding, electron affinities, and expected oxidation states compared with lighter halogens?
• Can techniques be developed to perform even rudimentary chemical experiments on single atoms of Ts or to perform rapid atom-at-a-time chemistry studies in gas-phase or surface chemistry setups?
• Which synthesis pathways or projectile-target combinations maximize production cross-sections for heavier superheavy isotopes?

Answering these questions will require both theoretical innovation and practical advances in experimental methods. For example, proposals exist for chemical studies that exploit rapid automated systems to study a few atoms before decay, but such experiments push current limits.

Cultural and Scientific Legacy

Tennessine’s naming recognizes regional contributions and showcases the collaborative nature of modern big-science projects. The element’s discovery reflects decades of incremental progress in nuclear physics, from building accelerators capable of delivering intense, stable beams to the radiochemical mastery of producing rare target isotopes.

Beyond its scientific import, names like tennessine serve as milestones that highlight how national and regional facilities contribute to global knowledge. The interplay of international teams on such discoveries demonstrates how complex scientific achievements often require networks of expertise, resources, and long-term commitment.

Future Directions

The future for tennessine research lies in three broad directions:

• Extended synthesis: Attempts to produce new isotopes of element 117 with longer half-lives, or to reach neighboring higher-Z elements, continue to be a priority for accelerator facilities worldwide.
• Improved detectors: Enhancing sensitivity, timing resolution, and background rejection can increase confidence in single-atom identifications and enable detection of rarer decay modes.
• Atom-at-a-time chemistry: Pushing the frontier of chemical experiments to cope with single atoms may one day reveal whether tennessine’s chemistry matches theoretical expectations or surprises us with novel behavior.

Each of these paths is technically demanding, but they promise to deepen our understanding of matter under extreme nuclear and relativistic regimes and to illuminate where the periodic table ultimately ends, or how it might be extended with surprising chemistry.

Selected Interesting Facts

• Tennessine’s name honors a U.S. state rather than a person or mythological figure — one of several modern elements named after places or regions.
• The actual production of the necessary actinide targets, such as berkelium-249, is a major scientific achievement that often involves months or years of reactor irradiations and careful separations.
• Despite grouping with the halogens, tennessine may show chemical tendencies that depart from the pattern seen in lighter group-17 elements because of strong relativistic and quantum effects on its electrons.
• Experimental events that identified tennessine were often based on observation of a few decay chains; such sparse data require rigorous statistical treatment and repeated verification before community acceptance.

Concluding Remarks

Tennessine is a frontier object: a fleeting, synthetic nuclide that serves as both a testing ground for nuclear theory and a challenge to chemical intuition. While it has no applied uses outside fundamental research, its synthesis and study push the boundaries of instrumentation, radiochemistry, and theory. Each atom produced is a small but vital piece of evidence in the broader quest to understand how far the periodic table can be extended, how nuclei behave under extreme conditions, and how relativistic quantum mechanics reshapes chemical reality at the upper reaches of atomic number.