Editing Hassium (section)

== Predicted properties ==

Various calculations suggest hassium should be the heaviest [[group&nbsp;8 element]] so far, consistently with the [[periodic law]]. Its properties should generally match those expected for a heavier homologue of osmium; as is the case for all [[transactinides]], a few deviations are expected to arise from [[relativistic effects]].{{sfn|Hoffman|Lee|Pershina|2006|pp=1666–1669}}

Very few properties of hassium or its compounds have been measured; this is due to its extremely limited and expensive production<ref name="Bloomberg">{{Cite news|last=Subramanian|first=S.|authorlink=Samanth Subramanian|url=https://www.bloomberg.com/news/features/2019-08-28/making-new-elements-doesn-t-pay-just-ask-this-berkeley-scientist|title=Making New Elements Doesn't Pay. Just Ask This Berkeley Scientist|website=[[Bloomberg Businessweek]]|date=28 August 2019|access-date=2020-01-18|archive-date=14 November 2020|archive-url=https://archive.today/20201114183428/https://www.bloomberg.com/news/features/2019-08-28/making-new-elements-doesn-t-pay-just-ask-this-berkeley-scientist|url-status=live}}</ref> and the fact that hassium (and its parents) decays very quickly. A few singular chemistry-related properties have been measured, such as enthalpy of adsorption of hassium tetroxide, but properties of hassium metal remain unknown and only predictions are available.

=== Relativistic effects ===

{{Main|Relativistic quantum chemistry}}
[[File:Energy levels of outermost orbitals of Hs and Os.jpg|left|thumb|upright=1.50|alt=Energy levels of outermost orbitals of Hs and Os|Energy levels of outermost orbitals of hassium and osmium atoms in [[electronvolt]]s, with and without taking relativistic effects into account. Note the lack of [[spin–orbit splitting]] (and thus the lack of distinction between d{{sub|3/2}} and d{{sub|5/2}} orbitals) in nonrelativistic calculations.]]

[[Relativistic quantum chemistry|Relativistic effects]] in hassium should arise due to the high charge of its nuclei, which causes the electrons around the nucleus to move faster—so fast their speed is comparable to the speed of light.{{sfn|Hoffman|Lee|Pershina|2006|p=1666}} There are three main effects: the direct relativistic effect, the indirect relativistic effect, and [[spin–orbit splitting]]. (The existing calculations do not account for [[Breit equation|Breit interactions]], but those are negligible, and their omission can only result in an uncertainty of the current calculations of no more than 2%.){{sfn|Hoffman|Lee|Pershina|2006|p=1669}}

As atomic number increases, so does the electrostatic attraction between an electron and the nucleus. This causes the velocity of the electron to increase, which leads to an increase in its [[Mass in special relativity|mass]]. This in turn leads to contraction of the [[atomic orbital]]s, most specifically the s and p{{sub|1/2}} orbitals. Their electrons become more closely attached to the atom and harder to pull from the nucleus. This is the direct relativistic effect. It was originally thought to be strong only for the innermost electrons, but was later established to significantly influence valence electrons as well.{{sfn|Hoffman|Lee|Pershina|2006|pp=1666–1667}}

Since the s and p{{sub|1/2}} orbitals are closer to the nucleus, they take a bigger portion of the electric charge of the nucleus on themselves ("shield" it). This leaves less charge for attraction of the remaining electrons, whose orbitals therefore expand, making them easier to pull from the nucleus. This is the indirect relativistic effect.{{sfn|Hoffman|Lee|Pershina|2006|p=1667–1668}} As a result of the combination of the direct and indirect relativistic effects, the Hs{{sup|+}} ion, compared to the neutral atom, lacks a 6d electron, rather than a 7s electron. In comparison, Os{{sup|+}} lacks a 6s electron compared to the neutral atom.{{sfn|Hoffman|Lee|Pershina|2006|p=1672}} The ionic radius (in oxidation state +8) of hassium is greater than that of osmium because of the relativistic expansion of the 6p{{sub|3/2}} orbitals, which are the outermost orbitals for an Hs{{sup|8+}} ion (although in practice such highly charged ions would be too polarized in chemical environments to have much reality).{{sfn|Hoffman|Lee|Pershina|2006|p=1676}}

There are several kinds of electron orbitals, denoted s, p, d, and f (g orbitals are expected to start being chemically active among elements after [[unbinilium|element 120]]). Each of these corresponds to an [[azimuthal quantum number]] ''l'': s to 0, p to 1, d to 2, and f to 3. Every electron also corresponds to a [[spin quantum number]] ''s'', which may equal either +1/2 or −1/2.<ref name="SO splitting">{{Cite web|url=http://www.xpsfitting.com/2012/08/spin-orbit-splitting.html|title=Spin Orbit Splitting|date=2012|website=X-ray Photoelectron Spectroscopy (XPS) Reference Pages|publisher=[[University of Western Ontario]]|access-date=2020-01-26|archive-date=25 January 2020|archive-url=https://web.archive.org/web/20200125152012/http://www.xpsfitting.com/2012/08/spin-orbit-splitting.html|url-status=live}}</ref> Thus, the [[total angular momentum quantum number]] ''j = l'' + ''s'' is equal to ''j'' = ''l'' ± 1/2 (except for ''l'' = 0, for which for both electrons in each orbital ''j ='' 0 + 1/2 = 1/2).<ref name="SO splitting" /> [[Spin (physics)|Spin]] of an electron relativistically [[spin–orbit interaction|interacts]] with its orbit, and this interaction leads to a split of a subshell into two with different energies (the one with ''j'' = ''l'' − 1/2 is lower in energy and thus these electrons more difficult to extract):<ref>{{cite book|last=Thayer|first=J. S.|chapter=Relativistic effects and the chemistry of the heavier main group elements|date=2010|title=Relativistic Methods for Chemists|volume=10|page=65|editor-last=Barysz|editor-first=M.|publisher=Springer Netherlands|doi=10.1007/978-1-4020-9975-5_2|isbn=978-1-4020-9974-8|editor2-last=Ishikawa|editor2-first=Ya.|series=Challenges and Advances in Computational Chemistry and Physics}}</ref> for instance, of the six 6p electrons, two become 6p{{sub|1/2}} and four become 6p{{sub|3/2}}. This is the spin–orbit splitting (also called subshell splitting or [[Jj coupling|''jj'' coupling]]).{{sfn|Hoffman|Lee|Pershina|2006|pp=1668–1669}}{{Efn|The spin–orbit interaction is the interaction between the [[magnetic field]] caused by the spin of an electron and the effective magnetic field caused by the [[electric field]] of a nucleus and movement of an electron orbiting it. (According to the [[special theory of relativity]], electric and magnetic fields are both occurrences of common [[electromagnetic field]]s that can be seen as more or less electric and more or less magnetic depending on the [[reference frame]]. The effective magnetic field from the reference frame of the electron is obtained from the nucleus's electric field after a relativistic transformation from the reference frame of the nucleus.) The splitting occurs because depending on the spin of an electron, it may be either attracted to or repealed by the nucleus; this attraction or repulsion is significantly weaker the electrostatic attraction between them and it can thus only somewhat affect the electron overall.<ref>{{Cite journal|last1=Spavieri|first1=G.|last2=Mansuripur|first2=M.|date=2015|title=Origin of the spin–orbit interaction|journal=[[Physica Scripta]]|volume=90|issue=8|pages=085501-1–085501-2|doi=10.1088/0031-8949/90/8/085501|issn=0031-8949|arxiv=1506.07239|bibcode=2015PhyS...90h5501S|s2cid=119196998}}</ref>}} It is most visible with p electrons,{{sfn|Hoffman|Lee|Pershina|2006|p=1669}} which do not play an important role in the chemistry of hassium,{{sfn|Hoffman|Lee|Pershina|2006|p=1673}} but those for d and f electrons are within the same order of magnitude{{sfn|Hoffman|Lee|Pershina|2006|p=1669}} (quantitatively, spin–orbit splitting in expressed in energy units, such as [[electronvolt]]s).<ref name="SO splitting" />

These relativistic effects are responsible for the expected increase of the [[ionization energy]], decrease of the [[electron affinity]], and increase of stability of the +8 oxidation state compared to osmium; without them, the trends would be reversed.{{sfn|Hoffman|Lee|Pershina|2006|p=1679}} Relativistic effects decrease the atomization energies of hassium compounds because the spin–orbit splitting of the d orbital lowers binding energy between electrons and the nucleus and because relativistic effects decrease [[ionic bond|ionic character]] in bonding.{{sfn|Hoffman|Lee|Pershina|2006|p=1679}}

=== Physical and atomic ===

The previous members of group{{spaces}}8 have high melting points: Fe, 1538°C; [[ruthenium|Ru]], 2334°C; Os, 3033°C. Like them, hassium is predicted to be a solid at room temperature<ref name="Oestlin" /> though its melting point has not been precisely calculated. Hassium should crystallize in the [[hexagonal close-packed]] structure ({{sup|''c''}}/{{sub|''a''}}{{spaces}}={{spaces}}1.59),<ref name="Oestlin" /> similarly to its lighter [[congener (chemistry)|congener]] osmium.<ref name="Oestlin" /> Pure metallic hassium is calculated<ref name="Oestlin" /><ref>{{cite journal |last1=Grossman |first1=J. C. |last2=Mizel |first2=A. |last3=Côté |first3=M. |last4=Cohen |first4=M. L. |last5=Louie |first5=S. G. |date=1999 |title=Transition metals and their carbides and nitrides: Trends in electronic and structural properties |journal=Phys. Rev. B |volume=60 |issue=9 |page=6344 |doi=10.1103/PhysRevB.60.6343 |bibcode=1999PhRvB..60.6343G |s2cid=18736376 |display-authors=3 }}</ref> to have a [[bulk modulus]] (resistance to uniform compression) of 450{{spaces}}[[pascal (unit)|GPa]], comparable with that of [[diamond]], 442{{spaces}}GPa.<ref>{{cite journal|last1=Cohen|first1=M. |journal=[[Physical Review B]] |volume=32|issue=12|pages=7988–7991|date=1985 |title=Calculation of bulk moduli of diamond and zinc-blende solids|doi=10.1103/PhysRevB.32.7988|pmid=9936971|bibcode=1985PhRvB..32.7988C}}</ref> Hassium is expected to be one of the densest of the 118 known elements, with a predicted density of 27–29&nbsp;g/cm{{sup|3}} vs. the 22.59&nbsp;g/cm{{sup|3}} measured for osmium.<ref name="density" /><ref name="kratz" />

Hassium's atomic radius is expected to be ≈126{{spaces}}pm.{{sfn|Hoffman|Lee|Pershina|2006|p=1691}} Due to relativistic stabilization of the 7s orbital and destabilization of the 6d orbital, the Hs{{sup|+}} ion is predicted to have an electron configuration of &#91;[[radon|Rn]]&#93;{{spaces}}5f{{sup|14}}{{spaces}}6d{{sup|5}}{{spaces}}7s{{sup|2}}, giving up a 6d electron instead of a 7s electron, which is the opposite of the behaviour of its lighter homologues. The Hs{{sup|2+}} ion is expected to have electron configuration [Rn]{{spaces}}5f{{sup|14}}{{spaces}}6d{{sup|5}}{{spaces}}7s{{sup|1}}, analogous to that calculated for the Os{{sup|2+}} ion.{{sfn|Hoffman|Lee|Pershina|2006|p=1672}} In [[chemical compound]]s, hassium is calculated to display bonding characteristic for a [[d-block]] element, whose bonding will be primarily executed by 6d{{sub|3/2}} and 6d{{sub|5/2}} orbitals; compared to the elements from the previous periods, 7s, 6p{{sub|1/2}}, 6p{{sub|3/2}}, and 7p{{sub|1/2}} orbitals should be more important.{{sfn|Hoffman|Lee|Pershina|2006|p=1677}}

=== Chemical ===

<div style="float: right; margin: 18px; font-size:85%;">
{| class="wikitable"
|+Stable oxidation states in group 8{{sfn|Greenwood|Earnshaw|1997|pp=27–28}}
! Element
!colspan="8"| Stable oxidation states
|-
|[[iron]]|| ||{{spaces}}{{spaces}}{{spaces}}{{spaces}}||+6|| || ||+3||+2
|-
|[[ruthenium]]||+8|| ||+6||+5||+4||+3||+2
|-
|[[osmium]]||+8|| ||+6||+5||+4||+3||+2
|}</div>

Hassium is the sixth member of the 6d series of transition metals and is expected to be much like the [[platinum group metal]]s.<ref name="DoiX">{{cite journal|doi=10.1595/147106708X297486|title=The Periodic Table and the Platinum Group Metals|date=2008|last1=Griffith|first1=W. P.|journal=Platinum Metals Review |volume=52|issue=2|pages=114–119|doi-access=free}}</ref> Some of these properties were confirmed by gas-phase chemistry experiments.<ref name="Duellmann">{{cite report|last1=Düllmann|first1=C. E.|date=2011 |url=http://www.yumpu.com/en/document/view/7293741/superheavy-element-research-superheavy-element-research |title=Superheavy Element Research Superheavy Element—News from GSI and Mainz |publisher=University Mainz |access-date=30 June 2019 |archive-url=https://web.archive.org/web/20181223030058/https://www.yumpu.com/en/document/view/7293741/superheavy-element-research-superheavy-element-research |archive-date=23 December 2018 |url-status=live}}</ref><ref name="HsO4">{{cite journal|last1=Düllmann|first1=C. E.|last2=Dressler|first2=R.|last3=Eichler|first3=B. |last4=Gäggeler |first4=H. W. |last5=Glaus |first5=F. |last6=Jost |first6=D. T. |last7=Piguet |first7=D. |last8=Soverna |first8=S. |last9=Türler |first9=A. |last10=Brüchle |first10=W. |last11=Eichler |first11=R. |last12=Jäger |first12=E. |last13=Pershina |first13=V. |last14=Schädel |first14=M. |last15=Schausten |first15=B. |last16=Schimpf |first16=E. |last17=Schött |first17=H.-J. |last18=Wirth |first18=G. |last19=Eberhardt |first19=K. |last20=Thörle |first20=P. |last21=Trautmann |first21=N. |last22=Ginter |first22=T. N. |last23=Gregorich|first23=K. E.|last24=Hoffman|first24=D. C.|last25=Kirbach|first25=U. W. |last26=Lee |first26=D. M. |last27=Nitsche |first27=H. |last28=Patin |first28=J. B. |last29=Sudowe |first29=R. |last30=Zielinski|first30=P. M. |last31=Timokhin|first31=S. N.|last32=Yakushev|first32=A. B. |last33=Vahle |first33=A. |last34=Qin |first34=Z. |display-authors=3 |date=2003 |title=First chemical investigation of hassium (Hs, Z=108) |journal=Czechoslovak Journal of Physics |volume=53 |issue=1 Supplement |pages=A291–A298 |doi=10.1007/s10582-003-0037-4 |bibcode = 2003CzJPS..53A.291D|s2cid=123402972 }}</ref><ref name="GSI-Hs">{{Cite web |url=http://www.gsi.de/documents/DOC-2003-Jun-29-2.pdf |title=Chemistry of Hassium|date=2002|publisher=Gesellschaft für Schwerionenforschung|archive-url=https://web.archive.org/web/20120311001032/http://www.gsi.de/documents/DOC-2003-Jun-29-2.pdf|archive-date=2012-03-11|access-date=2019-06-30}}</ref> The group{{spaces}}8 elements portray a wide variety of oxidation states but ruthenium and osmium readily portray their group oxidation state of +8; this state becomes more stable down the group.{{sfn|Greenwood|Earnshaw|1997|pp=27–28}}<ref name="superheavy-chemistry" /><ref name="Barnard">{{cite journal|title=Oxidation States of Ruthenium and Osmium|date=2004 |last1=Barnard|first1=C. F. J.|last2=Bennett|first2=S. C.|journal=[[Platinum Metals Review]]|volume=48 |issue=4|pages=157–158|doi=10.1595/147106704X10801|doi-access=free}}</ref> This oxidation state is extremely rare: among stable elements, only ruthenium, osmium, and xenon are able to attain it in reasonably stable compounds.{{efn|While iridium is known to show a +8 state in [[iridium tetroxide]], as well as a unique +9 state in the iridium tetroxide cation {{chem|IrO|4|+}}, the former is known only in [[matrix isolation]] and the latter in the gas phase, and no iridium compounds in such high oxidation states have been synthesized in macroscopic amounts.<ref>{{cite journal|doi=10.1002/anie.200902733 |pmid=19593837 |title=Formation and Characterization of the Iridium Tetroxide Molecule with Iridium in the Oxidation State +VIII |year=2009|last1=Gong|first1=Yu|last2=Zhou|first2=M.|last3=Kaupp|first3=M.|last4=Riedel|first4=S.|journal=[[Angewandte Chemie International Edition]]|volume=48 |issue=42|pages=7879–7883}}</ref><ref>{{cite journal |last1=Wang |first1=G. |last2=Zhou |first2=M. |last3=Goettel |first3=J. T. |last4=Schrobilgen |first4=G. G. |last5=Su |first5=J. |last6=Li |first6=J. |last7=Schlöder |first7=T. |last8=Riedel |first8=S. |display-authors=3 |date=2014 |title=Identification of an iridium-containing compound with a formal oxidation state of IX |journal=Nature |volume=514 |issue=7523 |pages=475–477 |doi=10.1038/nature13795 |pmid=25341786 |bibcode=2014Natur.514..475W|s2cid=4463905}}</ref>}} Hassium is expected to follow its congeners and have a stable +8 state,<ref name="HsO4" /> but like them it should show lower stable oxidation states such as +6, +4, +3, and +2.{{sfn|Hoffman|Lee|Pershina|2006|p=1691}}<ref name="hassocene" /> Hassium(IV) is expected to be more stable than hassium(VIII) in aqueous solution.{{sfn|Hoffman|Lee|Pershina|2006|p=1720}} Hassium should be a rather [[noble metal]].<ref>{{cite journal |last1=Nagame |first1=Yu. |last2=Kratz |first2=J. V. |last3=Schädel |first3=M. |date=2015 |title=Chemical studies of elements with Z ≥ 104 in liquid phase |journal=[[Nuclear Physics A]] |volume=944 |page=632 |doi=10.1016/j.nuclphysa.2015.07.013 |bibcode=2015NuPhA.944..614N |url=https://jopss.jaea.go.jp/search/servlet/search?5050598 |access-date=24 September 2019 |archive-date=12 December 2022 |archive-url=https://web.archive.org/web/20221212184356/https://jopss.jaea.go.jp/search/servlet/search?5050598 |url-status=live }}</ref> The [[standard reduction potential]] for the Hs<sup>4+</sup>/Hs couple is expected to be 0.4{{spaces}}V.{{sfn|Hoffman|Lee|Pershina|2006|p=1691}}

The group 8 elements show a distinctive [[oxide]] chemistry. All the lighter members have known or hypothetical tetroxides, MO{{sub|4}}.<ref name="FeO4">{{cite journal|title=Higher Oxidation States of Iron in Solid State: Synthesis and Their Mössbauer Characterization—Ferrates—ACS Symposium Series (ACS Publications)|date=2008|first1=Yu. D. |last1=Perfiliev|first2=V. K.|last2=Sharma|volume=48|issue=4 |pages=157–158|journal=Platinum Metals Review |doi=10.1595/147106704X10801|doi-access=free}}</ref> Their oxidizing power decreases as one descends the group. FeO{{sub|4}} is not known due to its extraordinarily large electron affinity—the amount of energy released when an electron is added to a neutral atom or molecule to form a negative ion<ref>{{cite journal|title=electron affinity, E{{sub|ea}}|date=2009|url=http://goldbook.iupac.org/E01977.html|journal=IUPAC Compendium of Chemical Terminology|editor-last=Nič|editor-first=M.|edition=2.1.0|publisher=International Union of Pure and Applied Chemistry|doi=10.1351/goldbook.e01977|isbn=978-0-9678550-9-7|access-date=2019-11-24|editor2-last=Jirát|editor2-first=J.|editor3-last=Košata|editor3-first=B.|editor4-last=Jenkins|editor4-first=A.|doi-access=free|archive-date=31 August 2014|archive-url=https://web.archive.org/web/20140831071649/http://goldbook.iupac.org/E01977.html|url-status=live}}</ref>—which results in the formation of the well-known [[oxyanion]] [[ferrate|ferrate(VI)]], {{chem|FeO|4|2-}}.<ref>{{Cite journal|title=FeO<sub>4</sub>: A unique example of a closed-shell cluster mimicking a superhalogen|doi=10.1103/PhysRevA.59.3681|date=1999|last1=Gutsev|first1=G. L.|last2=Khanna |first2=S.|last3=Rao|first3=B.|last4=Jena|first4=P. |journal=[[Physical Review A]]|volume=59|issue=5 |pages=3681–3684|bibcode=1999PhRvA..59.3681G}}</ref> [[Ruthenium tetroxide]], RuO<sub>4</sub>, which is formed by oxidation of ruthenium(VI) in acid, readily undergoes [[reduction-oxidation|reduction]] to ruthenate(VI), {{chem|RuO|4|2-}}.<ref>{{cite book |last1= Cotton|first1=S. A.|title= Chemistry of Precious Metals|date= 1997|publisher= Chapman and Hall|isbn= 978-0-7514-0413-5}}</ref><ref>{{Cite book |last1=Martín |first1=V. S. |last2=Palazón |first2=J. M. |last3=Rodríguez |first3=C. M. |last4=Nevill |first4=C. R. |chapter=Ruthenium(VIII) Oxide |doi=10.1002/047084289X.rr009.pub2 |title=Encyclopedia of Reagents for Organic Synthesis |year=2006 |isbn=978-0471936237}}</ref> Oxidation of ruthenium metal in air forms the dioxide, RuO<sub>2</sub>.<ref>{{cite journal |first1=G. M. |last1=Brown |first2=J. H. |last2=Butler |date=1997 |title=New method for the characterization of domain morphology of polymer blends using ruthenium tetroxide staining and low voltage scanning electron microscopy (LVSEM) |journal=Polymer |volume=38 |issue=15 |pages=3937–3945 |doi=10.1016/S0032-3861(96)00962-7}}</ref> In contrast, osmium burns to form the stable [[osmium tetroxide|tetroxide]], OsO<sub>4</sub>,<ref>{{cite book|title=Encyclopaedia of Occupational Health and Safety|last=Stellman|first=J. M. |chapter=Osmium |isbn=978-92-2-109816-4|date=1998 |publisher=International Labour Organization|pages=63.34|chapter-url=https://books.google.com/books?id=nDhpLa1rl44C|oclc=35279504 |url=https://archive.org/details/encyclopaediaofo0003unse|url-access=registration}}</ref><ref>{{Housecroft2nd|pages=671–673, 710}}</ref> which complexes with the hydroxide ion to form an osmium(VIII) -''ate'' complex, [OsO<sub>4</sub>(OH)<sub>2</sub>]<sup>2−</sup>.<ref name="thompson">{{cite web |author=Thompson, M. |publisher=[[Bristol University]] |title=Osmium tetroxide (OsO<sub>4</sub>) |url=http://www.chm.bris.ac.uk/motm/oso4/oso4h.htm |access-date=2012-04-07 |archive-url=https://web.archive.org/web/20130922133517/http://www.chm.bris.ac.uk/motm/oso4/oso4h.htm |archive-date=22 September 2013 |url-status=live}}</ref> Therefore, hassium should behave as a heavier homologue of osmium by forming of a stable, very volatile tetroxide HsO<sub>4</sub>,<ref name="Emsley2011" /><ref name="Duellmann" /><ref name="GSI-Hs" /><ref name="superheavy-chemistry">{{cite book |title=The Chemistry of Superheavy Elements |first=M. |last=Schädel |publisher=Springer |date=2003 |isbn=978-1402012501 |page=269 |access-date=17 November 2012 |url=https://books.google.com/books?id=3ItA4fExU7wC |archive-date=8 October 2024 |archive-url=https://web.archive.org/web/20241008102909/https://books.google.com/books?id=3ItA4fExU7wC |url-status=live }}</ref>{{sfn|Hoffman|Lee|Pershina|2006|p=1685}} which undergoes complexation with [[hydroxide]] to form a hassate(VIII), [HsO<sub>4</sub>(OH)<sub>2</sub>]<sup>2−</sup>.<ref name="CALLISTO" /> Ruthenium tetroxide and osmium tetroxide are both volatile due to their symmetrical [[tetrahedral molecular geometry]] and because they are charge-neutral; hassium tetroxide should similarly be a very volatile solid. The trend of the volatilities of the group{{spaces}}8 tetroxides is experimentally known to be RuO<sub>4</sub>{{spaces}}<{{spaces}}OsO<sub>4</sub>{{spaces}}>{{spaces}}HsO<sub>4</sub>, which confirms the calculated results. In particular, the calculated [[enthalpy|enthalpies]] of [[adsorption]]—the energy required for the [[adhesion]] of atoms, molecules, or ions from a gas, liquid, or dissolved solid to a [[surface science|surface]]—of HsO<sub>4</sub>, −(45.4{{spaces}}±{{spaces}}1){{spaces}}kJ/mol on [[quartz]], agrees very well with the experimental value of −(46{{spaces}}±{{spaces}}2){{spaces}}kJ/mol.<ref name=":1">{{cite journal |last1=Pershina |first1=V. |last2=Anton |first2=J. |last3=Jacob |first3=T. |date=2008 |title=Fully relativistic density-functional-theory calculations of the electronic structures of MO<sub>4</sub> (M = Ru, Os, and element 108, Hs) and prediction of physisorption |journal=Physical Review A |volume=78 |issue=3 |pages=032518 |doi=10.1103/PhysRevA.78.032518|bibcode=2008PhRvA..78c2518P }}</ref>