# Isotopes of tennessine

Tennessine ($_{117}$Ts) is the most-recently synthesized synthetic element, 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 isotopes. The first (and so far only) isotopes to be synthesized were $^{293}$Ts and $^{294}$Ts in 2009. The longer-lived isotope is $^{294}$Ts with a half-life of 51 ms.

## List of isotopes

| Nuclide | Z | N | Isotopic mass (Da) | Half-life | Decay mode | Daughter isotope |
| $^{293}$Ts | 117 | 176 | 293.20873(84)# | 22+8 −4 ms [25(6) ms] | α | $^{289}$Mc |
| $^{294}$Ts | 117 | 177 | 294.21084(64)# | 51+38 −16 ms [70(30) ms] | α | $^{290}$Mc |
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* ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
* ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

## 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.
| Target | Projectile | CN | Attempt result |
| $^{208}$Pb | $^{81}$Br | $^{289}$Ts | Yet to be attempted |
| $^{209}$Bi | $^{82}$Se | $^{291}$Ts | Yet to be attempted |
| $^{238}$U | $^{55}$Mn | $^{293}$Ts | Yet to be attempted |
| $^{243}$Am | $^{50}$Ti | $^{293}$Ts | Yet to be attempted |
| $^{249}$Bk | $^{48}$Ca | $^{297}$Ts | Successful reaction |

#### Hot fusion
##### $^{249}$Bk($^{48}$Ca,xn)$^{297−x}$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, $^{293}$Ts and $^{294}$Ts, were predicted to decay via relatively long decay chains as far as isotopes of dubnium or lawrencium.
* Calculated decay chains from the parent nuclei $^{293}$Ts and $^{294}$Ts
The team published a paper in April 2010 (first results were presented in January 2010) that six atoms of the isotopes $^{294}$Ts (one atom) and $^{293}$Ts (five atoms) were detected. $^{294}$Ts decayed by six alpha decays 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 $^{281}$Rg, which underwent spontaneous fission. The reaction was run at two different excitation energies, 35 MeV (dose 2×10$^{19}$) and 39 MeV (dose 2.4×10$^{19}$). 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, identified a further two atoms of $^{286}$Nh from decay of $^{294}$Ts. 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

| Isotope | Year discovered | Reaction |
| $^{294}$Ts | 2009 | $^{249}$Bk($^{48}$Ca,3n) |
| $^{293}$Ts | 2009 | $^{249}$Bk($^{48}$Ca,4n) |

### 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
| Target | Projectile | CN | Channel (product) | σ$_{max}$ | Model |
| $^{209}$Bi | $^{82}$Se | $^{291}$Ts | 1n ($^{290}$Ts) | 15 fb | DNS |
| $^{209}$Bi | $^{79}$Se | $^{288}$Ts | 1n ($^{287}$Ts) | 0.2 pb | DNS |
| $^{232}$Th | $^{59}$Co | $^{291}$Ts | 2n ($^{289}$Ts) | 0.1 pb | DNS |
| $^{238}$U | $^{55}$Mn | $^{293}$Ts | 2-3n ($^{291,290}$Ts) | 70 fb | DNS |
| $^{244}$Pu | $^{51}$V | $^{295}$Ts | 3n ($^{292}$Ts) | 0.6 pb | DNS |
| $^{248}$Cm | $^{45}$Sc | $^{293}$Ts | 4n ($^{289}$Ts) | 2.9 pb | DNS |
| $^{246}$Cm | $^{45}$Sc | $^{291}$Ts | 4n ($^{287}$Ts) | 1 pb | DNS |
| $^{249}$Bk | $^{48}$Ca | $^{297}$Ts | 3n ($^{294}$Ts) | 2.1 pb ; 3 pb | DNS |
| $^{247}$Bk | $^{48}$Ca | $^{295}$Ts | 3n ($^{292}$Ts) | 0.8, 0.9 pb | DNS |

#### 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, $^{289–303}$Ts) to be around 0.1–40 ms.