Tennessine

Tennessine
The location of Tennessine
Symbol	Ts
Number	117
Group, Period	17, 7 (see Note a.)
Electrons per shell	2,8,18,32,32,18,7 (Predicted) (See Note a.)
Discoverer	JINR and Yuri Oganessian
Date discovered	5 April 2010
Location discovered	JINR, Dubna, Russia
Atomic Mass	not applicable
Category	Halogen (Predicted) (See Note a.)

Tennessine (Ts) is the name of element 117.  Wikipedia has an article which provides a lot of information about the element.  This article will focus on things Wikipedia does not stress: heavy isotopes and formation.

Maximum predicted half-lives of Ts isotopes are on the order of 1 - 2 sec, and no isotopes are predicted to be daughters of long-lived nuclides.

A large number of Ts isotopes can form during a neutron star merger or comparable event, but all of these are heavier than ³²⁴Ts, since lighter nuclides will fission at Z < 117. Supernovae are unlikely to be able to form this element.

Any Ts which does form will disappear within 316 sec of the event which led to its formation. This means that the element exists only as positive ions, except in the extraordinarily rare case of synthesis in a laboratory.

Nuclear Properties

Information sources

This article uses two main resources chosen because of their independence from one another.

At least one document maps half-life and decay mode for elements below Z = 175 from the neutron dripline down to isotopes which are too neutron-poor to survive any appreciable length of time⁽¹⁾. Maps on pp 15 & 18 address the entire (Z,N) region covered, but report only the dominant decay mode and report half-lives only to within a band three orders of magnitude wide (0.001 - 1 sec, for example). More detailed estimates of these properties can be extracted from maps on pp 11 & 12, but only for a limited range of Z and N. Half-life data are reported by colors, which makes numerical estimates laborious to produce. This document is connected to Japan's KTUY model.

An independent map of half-lives and decay modes exists⁽²⁾. This one is limited to A = 339, as well as to Z = 132. It does not show short-lived isotopes well, and gives half-lives only within rather broad and awkward bands. It does show multiple decay modes for single nuclides. It originates from models used by the Russian agency JINR, so is completely independent of Ref. 1.

Japan Atomic Energy Agency (JAEA) maintains an on-line chart of nuclides which includes decay properties of many predicted nuclides⁽³⁾ - unlike charts published by Korea Atomic Energy Research Institute (KAERI) or the (U.S.) National Nuclear Data Center (NNDC). This chart gives separate numerical values for partial half-lives against fission, beta emission (both b^- and b⁺), and alpha emission. These appear to be systematically too long, but are probably reliable to within an order of magnitude.

Predicted properties

Even-N isotopes from the neutron dripline down to ³⁸⁰Ts decay predominantly by beta emission with half-lives in the 0.001 - 1 sec range. Half-lives aren't reported, but the properties of beta decay indicate that half-lives close to 0.001 sec are likely⁽⁴⁾. Odd-N drops in this band decay by neutron emission.

All isotopes in the band ³⁷⁹Ts to ³⁷⁰Ts are predicted to have half-lives in the 0.001 - 1 sec range. Dominant decay modes are a mixture of fission and beta emission. Which mode dominates depends on N, with specific values of N associated with fission over a range of Z values. It is likely that both modes are significant for all isotopes.

Isotopes in the band ³⁶⁹Ts to ³³⁵Ts are predicted to decay by beta emission. All have half-lives in the 0.001 - 1 sec range.

Isotopes in the band ³³⁴Ts to ³²⁹Ts are predicted to have fission as their principal decay modes, but to have half-lives in the 0.001 - 1 sec range. Beta decay is likely to be a secondary decay mode for these isotopes.

³²⁸Ts to ³²⁶Ts are predicted to decay by fission and to have half-lives in the 10^-06 - 0.001 sec range.

Ref 1 predicts a gap from ³²⁵Ts to ³¹⁰Ts, which is predicted to be occupied by nuclear drops or very short-lived nuclides. Fission is, of course, the predicted decay mode. Ref, 2 predicts a similar gap. It does not show any stabilization near N = 198.

Between ³⁰⁹Ts and ³⁰⁶Ts, Ref. 1 and Ref. 2 agree that fission is the predominant decay mode, but differ with respect to half-lives. Ref. 1 indicates half-lives up to the 0.001 - 1 sec range, while Ref. 2 predicts half-lives under 10^-06 sec.

Between ³⁰⁵Ts and ³⁰³Ts, Alpha decay is predicted by both sources. Ref. 1 predicts a dip in half-lives in this band. It is weak, but neutron count in this band is 188 to 186 - exactly where short alpha half-lives are to be expected above a neutron shell closure. This dip is invisible at higher Z. Ref. 3 indicates that half-lives in this band are close to, or below, 0.001 sec.

Below ³⁰³Ts, prediction of decay properties become numerous. These generally agree that alpha decay will predominate and that half-lives will peak just below ³⁰¹Ts (for which N = 184). Further comparison is out of scope for this article. Ref. 3 indicates that ³⁰⁰Ts and ²⁹⁶Ts should have half-lives between 1 - 2 sec long, that ²⁹⁸Ts will be close to 1 sec, and that all others are shorter. It is worth noting that ²⁹⁵Ts and ²⁹²Ts both have predicted half-lives exceeding 0.5 sec, much longer than the observed half-lives of ²⁹⁴Ts and ²⁹³Ts.

The lightest isotope reported by any of Refs. 1 through 3 is ²⁸¹Ts. There may be a few lighter nuclides with half-lives in the 10^-14 - 10^-09 sec range, but half-lives will quickly decline below the minimum needed for a nuclear drop to qualify as a nuclide.

Occurrence

Formation

All even-N nuclear drops from the neutron dripline to ³⁸²Ts are predicted to be nuclides. Some of these isotopes can form directly as a neutron star disintegrates. Most of them however require a chain of beta decays to form. From neutron dripline to ³⁸²Ts, beta decay chains pass through Ts. Between ³⁸¹Ts and ³⁶⁷Ts, most beta decay chains terminate at Z <= 117, but most a few pass through to higher Z. A third band exists from ³⁶⁶Ts to ³³⁵Ts, in which beta decay chains from the neutron dripline pass through Ts. Below that is a fourth band extending from ³³⁴Ts to ²⁹³Ts in which beta decay chains from the neutron dripline are truncated by fission at Z < 117. Lighter isotopes cannot form since beta decay chains are truncated at Z < 118. It appears to be possible that material ejected from a disintegrating neutron star will allow all the nuclides to form.

Neutron capture may be able to produce nuclides up to A around 380 before fission attrition stops further growth. Neutron capture is expected to contribute to formation of all significant Ts isotopes.

Persistence

³²⁴Ts and heavier isotopes which can form will vanish within 1000 sec after a supernova or neutron star merger which led to their formation.

³²³Ts through ³¹¹Ts lie at a higher Z than the terminating nuclides of short-lived beta-decay chains in this mass range.

³¹⁰Ts and lighter isotopes are predicted to have short half-lives and to be incapable of forming via beta decay from the dripline.

Atomic Properties

If the threshold for extinction is set at a molar concentration of 1.5E-30 - which equals [²¹⁸At] in the earth as a whole - all isotopes of Ts have become extinct within 10^2.5 (316) sec after the event which led to their formation. At this point Ts atoms will be at a temperature on the order of 1.5E06 K^(a), which is equivalent to a mean KE of 136 eV/atom. Based on predicted ionization energies and energy eigenstates, Ts will exist only as positive ions, with Ts⁺⁸ (loss of all 7s, 7p_1/2, and 7p_3/2 electrons) likely to be its minimum charge. It may exist - briefly - as bare nuclei, but only at emperatures above 10⁹ K.

Tennessine has no chemical properties. It is never cool enough for the two-charge-center / bound-electron phenomena we call chemistry.

References

1. "Decay Modes and a Limit of Existence of Nuclei"; H. Koura; 4th Int. Conf. on the Chemistry and Physics of Transactinide Elements; Sept. 2011.

2. “Systematic Study of Decay Properties of Heaviest Elements.”; Y. M. Palenzuelaa, L. F. Ruiza, A. Karpov, and W. Greiner; Bulletin of the Russian Academy of Sciences, Physics.  Vol . 76, No.11, pp 1165 – 1177; 2012

3. "Chart of the Nuclides, 2014", Japan Atomic Energy Agency; website available using "chart of nuclides" and "JAEA" as internet search terms.

4. "Nuclear Properties for Astrophysical Applications"; P. Moller & J. R. Nix; Los Alamos National Laboratory website; search by "LANL, T2", then "Nuclear Properties for Astrophysical Applications".

Notes

a. Except for one special case: a low-mass, population I (metal-rich) star, with a planet large enough to have an atmosphere and in an orbit which makes liquid water present in contact with both atmosphere and sunlight, several billion years to allow physicists and chemists to evolve, and a cultural willing-ness to spend vast sums of money to study Tennessine.

9-Period Periodic Table of Elements
1	1 H																																																																	2 He
2	3 Li	4 Be																																																																	5 B	6 C	7 N	8 O	9 F	10 Ne
3	11 Na	12 Mg																																																																	13 Al	14 Si	15 P	16 S	17 Cl	18 Ar
4	19 K	20 Ca																																																																	21 Sc	22 Ti	23 V	24 Cr	25 Mn	26 Fe	27 Co	28 Ni	29 Cu	30 Zn	31 Ga	32 Ge	33 As	34 Se	35 Br	36 Kr
5	37 Rb	38 Sr																																																																	39 Y	40 Zr	41 Nb	42 Mo	43 Tc	44 Ru	45 Rh	46 Pd	47 Ag	48 Cd	49 In	50 Sn	51 Sb	52 Te	53 I	54 Xe
6	55 Cs	56 Ba																																																					57 La	58 Ce	59 Pr	60 Nd	61 Pm	62 Sm	63 Eu	64 Gd	65 Tb	66 Dy	67 Ho	68 Er	69 Tm	70 Yb	71 Lu	72 Hf	73 Ta	74 W	75 Re	76 Os	77 Ir	78 Pt	79 Au	80 Hg	81 Tl	82 Pb	83 Bi	84 Po	85 At	86 Rn
7	87 Fr	88 Ra																																																					89 Ac	90 Th	91 Pa	92 U	93 Np	94 Pu	95 Am	96 Cm	97 Bk	98 Cf	99 Es	100 Fm	101 Md	102 No	103 Lr	104 Rf	105 Db	106 Sg	107 Bh	108 Hs	109 Mt	110 Ds	111 Rg	112 Cn	113 Nh	114 Fl	115 Mc	116 Lv	117 Ts	118 Og
8	119 Uue	120 Ubn																															121 Ubu	122 Ubb	123 Ubt	124 Ubq	125 Ubp	126 Ubh	127 Ubs	128 Ubo	129 Ube	130 Utn	131 Utu	132 Utb	133 Utt	134 Utq	135 Utp	136 Uth	137 Uts	138 Uto	139 Ute	140 Uqn	141 Uqu	142 Uqb	143 Uqt	144 Uqq	145 Uqp	146 Uqh	147 Uqs	148 Uqo	149 Uqe	150 Upn	151 Upu	152 Upb	153 Upt	154 Upq	155 Upp	156 Uph	157 Ups	158 Upo	159 Upe	160 Uhn	161 Uhu	162 Uhb	163 Uht	164 Uhq	165 Uhp	166 Uhh	167 Uhs	168 Uho	169 Uhe	170 Usn	171 Usu	172 Usb
9	173 Ust	174 Usq
Alkali metal Alkaline earth metal Lanthanide Actinide Superactinide Transition metal Post-transition metal Metalloid Other nonmetal Halogen Noble gas predicted predicted predicted predicted predicted predicted predicted predicted predicted

(10-02-20)