Tennessine Tennessine is a synthetic chemical element with the symbol Ts and atomic number 117. It is the second-heaviest known element and the penultimate element of the 7th period of the periodic table. The discovery of tennessine was officially anno ...

(₁₁₇Ts) is the most-recently synthesized

synthetic element A synthetic element is one of 24 known chemical elements that do not occur naturally on Earth: they have been created by human manipulation of fundamental particles in a nuclear reactor, a particle accelerator, or the explosion of an atomic bomb; ...

, and much of the data is hypothetical. As for any synthetic element, a standard atomic weight cannot be given. Like all synthetic elements, it has no

stable isotope The term stable isotope has a meaning similar to stable nuclide, but is preferably used when speaking of nuclides of a specific element. Hence, the plural form stable isotopes usually refers to isotopes of the same element. The relative abundanc ...

s. The first (and so far only)

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numb ...

s to be synthesized were ²⁹³Ts and ²⁹⁴Ts in 2009. The longer-lived isotope is ²⁹⁴Ts with a

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable at ...

of 51 ms.

List of isotopes

, - , ²⁹³Ts , style="text-align:right" , 117 , style="text-align:right" , 176 , 293.20873(84)# , , α , ²⁸⁹Mc , , - , ²⁹⁴Ts , style="text-align:right" , 117 , style="text-align:right" , 177 , 294.21084(64)# , , α , ²⁹⁰Mc ,

Isotopes and nuclear properties

Nucleosynthesis

Target-projectile combinations leading to Z=117 compound nuclei

The below table contains various combinations of targets and projectiles that could be used to form compound nuclei with atomic number 117.

Hot fusion

=²⁴⁹Bk(⁴⁸Ca,''x''n)^297−''x''Ts (''x''=3,4)

= Between July 2009 and February 2010, the team at the JINR (Flerov Laboratory of Nuclear Reactions) ran a 7-month-long experiment to synthesize tennessine using the reaction above. The expected cross-section was of the order of 2 pb. The expected evaporation residues, ²⁹³Ts and ²⁹⁴Ts, were predicted to decay via relatively long decay chains as far as isotopes of

dubnium Dubnium is a synthetic chemical element with the symbol Db and atomic number 105. It is highly radioactive: the most stable known isotope, dubnium-268, has a half-life of about 16 hours. This greatly limits extended research on the element. ...

lawrencium Lawrencium is a synthetic chemical element with the symbol Lr (formerly Lw) and atomic number 103. It is named in honor of Ernest Lawrence, inventor of the cyclotron, a device that was used to discover many artificial radioactive elements. A radio ...

. Image:293Uus and 294Uus calculated decay chains.jpg, Calculated decay chains from the parent nuclei ²⁹³Ts and ²⁹⁴Ts
The team published a paper in April 2010 (first results were presented in January 2010Recommendations: 31st meeting, PAC for Nuclear Physics
) that six atoms of the isotopes ²⁹⁴Ts (one atom) and ²⁹³Ts (five atoms) were detected. ²⁹⁴Ts decayed by six

alpha decay Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and thereby transforms or 'decays' into a different atomic nucleus, with a mass number that is reduced by four and an at ...

s down as far as the new isotope ²⁷⁰ Db, which underwent apparent spontaneous fission. The lighter odd-even isotope underwent just three alpha decays, as far as ²⁸¹Rg, which underwent spontaneous fission. The reaction was run at two different excitation energies, 35 MeV (dose 2×10¹⁹) and 39 MeV (dose 2.4×10¹⁹). Initial decay data was published as a preliminary presentation on the JINR website. A further experiment in May 2010, aimed at studying the chemistry of the granddaughter of tennessine,

nihonium Nihonium is a synthetic chemical element with the symbol Nh and atomic number 113. It is extremely radioactive; its most stable known isotope, nihonium-286, has a half-life of about 10 seconds. In the periodic table, nihonium is a transactinide ...

, identified a further two atoms of ²⁸⁶Nh from decay of ²⁹⁴Ts. The original experiment was repeated successfully by the same collaboration in 2012 and by a joint German–American team in May 2014, confirming the discovery.

Chronology of isotope discovery

Theoretical calculations

Evaporation residue cross sections

The below table contains various targets-projectile combinations for which calculations have provided estimates for cross section yields from various neutron evaporation channels. The channel with the highest expected yield is given. DNS = Di-nuclear system; σ = cross section

Decay characteristics

Theoretical calculations in a quantum tunneling model with mass estimates from a macroscopic-microscopic model predict the alpha-decay half-lives of isotopes of tennessine (namely, ^289–303Ts) to be around 0.1–40 ms.

References

{{Navbox element isotopes Tennessine