Editing Tennessine (section)

=== Chemical ===
{{multiple image
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| image1    = T-shaped-3D-balls.png
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| alt1      = Skeletal model of a planar molecule with a central atom (iodine) symmetrically bonded to three (fluorine) atoms to form a big right-angled T
| caption1  = {{chem|IF|3}} has a T-shape configuration.
| image2    = Trigonal-3D-balls.png
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| alt2      = Skeletal model of a trigonal molecule with a central atom (tennessine) symmetrically bonded to three peripheral (fluorine) atoms
| caption2  = {{chem|TsF|3}} is predicted to have a trigonal configuration.
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The known isotopes of tennessine, <sup>293</sup>Ts and <sup>294</sup>Ts, are too short-lived to allow for chemical experimentation at present. Nevertheless, many chemical properties of tennessine have been calculated.<ref name="Moody">{{cite book |chapter=Synthesis of Superheavy Elements |last1=Moody |first1=Ken |editor1-first=Matthias |editor1-last=Schädel |editor2-first=Dawn |editor2-last=Shaughnessy |title=The Chemistry of Superheavy Elements |publisher=Springer Science & Business Media |edition=2nd |pages=24–8 |isbn=9783642374661|date=2013-11-30 }}</ref> Unlike the lighter group 17 elements, tennessine may not exhibit the chemical behavior common to the halogens.<ref name="notgonnabeahalogen">{{Cite web|author = <!--no author; by design-->|title = Superheavy Element 117 Confirmed – On the Way to the "Island of Stability"|url = https://www.superheavies.de/english/research_program/highlights_element_117.htm#Is%20Element%20117%20a%20Metal|publisher = GSI Helmholtz Centre for Heavy Ion Research|access-date = 2015-07-26|archive-url = https://web.archive.org/web/20180803133710/https://www.superheavies.de/english/research_program/highlights_element_117.htm#Is%20Element%20117%20a%20Metal|archive-date = 2018-08-03|url-status = dead}}</ref> For example, fluorine, chlorine, bromine, and iodine routinely accept an electron to achieve the more stable [[electronic configuration]] of a [[noble gas]], obtaining eight electrons ([[octet rule|octet]]) in their valence shells instead of seven.<ref>{{cite web |last=Bader |first=R. F. W. |url=https://miranda.chemistry.mcmaster.ca/esam/ |title=An introduction to the electronic structure of atoms and molecules |publisher=McMaster University |access-date=2008-01-18 |archive-date=12 October 2007 |archive-url=https://web.archive.org/web/20071012213137/http://miranda.chemistry.mcmaster.ca/esam/ |url-status=dead }}</ref> This ability weakens as atomic weight increases going down the group; tennessine would be the least willing group 17 element to accept an electron. Of the oxidation states it is predicted to form, −1 is expected to be the least common.<ref name="Haire" /> The [[standard reduction potential]] of the Ts/Ts<sup>−</sup> couple is predicted to be −0.25&nbsp;V; this value is negative, unlike for all the lighter halogens.{{Fricke1975}}

There is another opportunity for tennessine to complete its octet—by forming a [[covalent bond]]. Like the halogens, when two tennessine atoms meet they are expected to form a Ts–Ts bond to give a [[diatomic molecule]]. Such molecules are commonly bound via single [[sigma bond]]s between the atoms; these are different from [[pi bond]]s, which are divided into two parts, each shifted in a direction perpendicular to the line between the atoms, and opposite one another rather than being located directly between the atoms they bind. Sigma bonding has been calculated to show a great [[antibonding]] character in the At<sub>2</sub> molecule and is not as favorable energetically. Tennessine is predicted to continue the trend; a strong pi character should be seen in the bonding of Ts<sub>2</sub>.<ref name="Haire" />{{sfn|Pershina|2010|p=504}} The molecule tennessine chloride (TsCl) is predicted to go further, being bonded with a single pi bond.{{sfn|Pershina|2010|p=504}}

Aside from the unstable −1 state, three more oxidation states are predicted; +5, +3, and +1. The +1 state should be especially stable because of the destabilization of the three outermost 7p<sub>3/2</sub> electrons, forming a stable, half-filled subshell configuration;<ref name="Haire" /> astatine shows similar effects.{{sfn|Thayer|2010|p=84}} The +3 state should be important, again due to the destabilized 7p<sub>3/2</sub> electrons.<ref name="Seaborg" /> The +5 state is predicted to be uncommon because the 7p<sub>1/2</sub> electrons are oppositely stabilized.<ref name="Haire" /> The +7 state has not been shown—even computationally—to be achievable. Because the 7s electrons are greatly stabilized,<!-- While the inert pair effect is the one working here, we can go without it. The whole thing is just a part of the SO interactions the text is mostly talking about. In the contexts not requiring advanced SO talks (indium, lead), the mention of the more obvious inert pair is really enough. Here the context is different from those. We do mention that before --> it has been hypothesized that tennessine effectively has only five valence electrons.<ref name="trifluoride" />

The simplest possible tennessine compound would be the monohydride, TsH. The bonding is expected to be provided by a 7p<sub>3/2</sub> electron of tennessine and the 1s electron of hydrogen. The non-bonding nature of the 7p<sub>1/2</sub> [[spinor]] is because tennessine is expected not to form purely sigma or pi bonds.<ref name="117H" /> Therefore, the destabilized (thus expanded) 7p<sub>3/2</sub> spinor is responsible for bonding.{{sfn|Stysziński|2010|pp=144–146}} This effect lengthens the TsH molecule by 17&nbsp;picometers compared with the overall length of 195&nbsp;pm.<ref name="117H">{{cite journal |journal=Journal of Chemical Physics |title=Spin-orbit effects on the transactinide p-block element monohydrides MH (M=element 113-118) |display-authors=3 |last1=Han |first1=Y.-K. |last2=Bae |first2=Cheolbeom |last3=Son |first3=Sang-Kil |last4=Lee |first4=Yoon Sup |volume=112 |issue=6 |pages=2684–2691 |date=2000 |bibcode=2000JChPh.112.2684H |doi=10.1063/1.480842 |s2cid = 9959620}}</ref> Since the tennessine p electron bonds are two-thirds sigma, the bond is only two-thirds as strong as it would be if tennessine featured no spin–orbit interactions.<ref name="117H" /> The molecule thus follows the trend for halogen hydrides, showing an increase in bond length and a decrease in dissociation energy compared to AtH.<ref name="Haire" /> The molecules [[thallium|Tl]]Ts and [[Nihonium|Nh]]Ts may be viewed analogously, taking into account an opposite effect shown by the fact that the element's p<sub>1/2</sub> electrons are stabilized. These two characteristics result in a relatively small [[electric dipole moment|dipole moment]] (product of difference between electric charges of atoms and [[displacement (vector)|displacement]] of the atoms) for TlTs; only 1.67&nbsp;[[debye (unit)|D]],{{efn|For comparison, the values for the ClF, HCl, SO, HF, and HI molecules are 0.89&nbsp;D, 1.11&nbsp;D, 1.55&nbsp;D, 1.83&nbsp;D, and 1.95&nbsp;D. Values for molecules which do not form at [[standard conditions]], namely GeSe, SnS, TlF, BaO, and NaCl, are 1.65&nbsp;D, ~3.2&nbsp;D, 4.23&nbsp;D, 7.95&nbsp;D, and 9.00&nbsp;D.<ref>{{cite book|first=D. R.|last=Lide |title=CRC Handbook of Chemistry and Physics|edition=84th |publisher=[[CRC Press]]|date=2003|chapter=Section 9, Molecular Structure and Spectroscopy|pages=9–45, 9–46|isbn=978-0-8493-0484-2}}</ref>}} the positive value implying that the negative charge is on the tennessine atom. For NhTs, the strength of the effects are predicted to cause a transfer of the electron from the tennessine atom to the nihonium atom, with the dipole moment value being −1.80&nbsp;D.{{sfn|Stysziński|2010|pp=139–146}} The spin–orbit interaction increases the dissociation energy of the TsF molecule because it lowers the electronegativity of tennessine, causing the bond with the extremely electronegative fluorine atom to have a more [[ionic bond|ionic]] character.<ref name="117H" /> Tennessine monofluoride should feature the strongest bonding of all group 17 monofluorides.<ref name="117H" />

[[VSEPR theory]] predicts a [[T-shaped molecular geometry|bent-T-shaped]] [[molecular geometry]] for the group 17 trifluorides. All known halogen trifluorides have this molecular geometry and have a structure of AX<sub>3</sub>E<sub>2</sub>—a central atom, denoted A, surrounded by three [[ligand]]s, X, and two unshared [[electron pair]]s, E. If relativistic effects are ignored, TsF<sub>3</sub> should follow its lighter [[Congener (chemistry)|congeners]] in having a bent-T-shaped molecular geometry. More sophisticated predictions show that this molecular geometry would not be energetically favored for TsF<sub>3</sub>, predicting instead a [[trigonal planar molecular geometry]] (AX<sub>3</sub>E<sub>0</sub>). This shows that VSEPR theory may not be consistent for the superheavy elements.<ref name="trifluoride">{{Cite journal | last1 = Bae | first1 = Ch.| last2 = Han | first2 = Y.-K. | last3 = Lee | first3 = Yo. S. | doi = 10.1021/jp026531m | title = Spin−Orbit and Relativistic Effects on Structures and Stabilities of Group 17 Fluorides EF<sub>3</sub> (E = I, At, and Element 117): Relativity Induced Stability for the ''D<sub>3h</sub>'' Structure of (117)F<sub>3</sub> | journal = The Journal of Physical Chemistry A | volume = 107 | issue = 6 | pages = 852–858 | date = 2003-01-18 | bibcode = 2003JPCA..107..852B }}</ref> The TsF<sub>3</sub> molecule is predicted to be significantly stabilized by spin–orbit interactions; a possible rationale may be the large difference in electronegativity between tennessine and fluorine, giving the bond a partially ionic character.<ref name="trifluoride" />