Ununennium

Ununennium, also known as eka-francium or element 119, is the hypothetical chemical element with symbol Uue and atomic number 119. Ununennium and Uue are the temporary systematic IUPAC name and symbol respectively, which are used until the element is discovered, confirmed, and a permanent name is decided upon. In the periodic table of the elements, it is expected to be an s-block element, an alkali metal, and the first element in the eighth period. It is the lightest element that has not yet been synthesized.

Ununennium, 119Uue
Theoretical element
Ununennium
Pronunciation/ˌuːn.uːnˈɛniəm/ ⓘ ​(OON-oon-EN-ee-əm)
Alternative nameselement 119, eka-francium
Ununennium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Ununennium Unbinilium
Unquadtrium Unquadquadium Unquadpentium Unquadhexium Unquadseptium Unquadoctium Unquadennium Unpentnilium Unpentunium Unpentbium Unpenttrium Unpentquadium Unpentpentium Unpenthexium Unpentseptium Unpentoctium Unpentennium Unhexnilium Unhexunium Unhexbium Unhextrium Unhexquadium Unhexpentium Unhexhexium Unhexseptium Unhexoctium Unhexennium Unseptnilium Unseptunium Unseptbium
 Unbiunium Unbibium Unbitrium Unbiquadium Unbipentium Unbihexium Unbiseptium Unbioctium Unbiennium Untrinilium Untriunium Untribium Untritrium Untriquadium Untripentium Untrihexium Untriseptium Untrioctium Untriennium Unquadnilium Unquadunium Unquadbium
 Fr
↑
Uue
↓
—
oganesson ← ununennium → unbinilium
Atomic number (Z)119
Groupgroup 1: hydrogen and alkali metals
Periodperiod 8 (theoretical, extended table)
Block  s-block
Electron configuration[Og] 8s1 (predicted)[1]
Electrons per shell2, 8, 18, 32, 32, 18, 8, 1 (predicted)
Physical properties
Phase at STPunknown phase (could be solid or liquid)[1]
Melting point273–303 K ​(0–30 °C, ​32–86 °F) (predicted)[1]
Boiling point903 K ​(630 °C, ​1166 °F) (predicted)[2]
Density (near r.t.)3 g/cm3 (predicted)[1]
Heat of fusion2.01–2.05 kJ/mol (extrapolated)[3]
Atomic properties
Oxidation states(+1), (+3), (+5) (predicted)[1][4]
ElectronegativityPauling scale: 0.86 (predicted)[5]
Ionization energies
  • 1st: 463.1 kJ/mol
  • 2nd: 1698.1 kJ/mol
  • (predicted)[6]
Atomic radiusempirical: 240 pm (predicted)[1]
Covalent radius263–281 pm (extrapolated)[3]
Other properties
Crystal structure ​body-centered cubic (bcc)
Body-centered cubic crystal structure for ununennium

(extrapolated)[7]
CAS Number54846-86-5
History
NamingIUPAC systematic element name
Isotopes of ununennium
Experiments and theoretical calculations

An attempt to synthesize the element has been ongoing since 2018 in RIKEN in Japan. The Joint Institute for Nuclear Research in Dubna, Russia, plans to make an attempt at some point in the future, but a precise date has not been released to the public. Theoretical and experimental evidence has shown that the synthesis of ununennium will likely be far more difficult than that of the previous elements.

Ununennium's position as the seventh alkali metal suggests that it would have similar properties to its lighter congeners. However, relativistic effects may cause some of its properties to differ from those expected from a straight application of periodic trends. For example, ununennium is expected to be less reactive than caesium and francium and closer in behavior to potassium or rubidium, and while it should show the characteristic +1 oxidation state of the alkali metals, it is also predicted to show the +3 and +5 oxidation states, which are unknown in any other alkali metal.

Introduction
A graphic depiction of a nuclear fusion reaction
A graphic depiction of a nuclear fusion reaction. Two nuclei fuse into one, emitting a neutron. Thus far, reactions that created new elements were similar, with the only possible difference that several singular neutrons sometimes were released, or none at all.
External video
video icon Visualization of unsuccessful nuclear fusion, based on calculations by the Australian National University[8]

The heaviest[lower-alpha 1] atomic nuclei are created in nuclear reactions that combine two other nuclei of unequal size[lower-alpha 2] into one; roughly, the more unequal the two nuclei in terms of mass, the greater the possibility that the two react.[14] The material made of the heavier nuclei is made into a target, which is then bombarded by the beam of lighter nuclei. Two nuclei can fuse into one only if they approach each other closely enough; normally, nuclei (all positively charged) repel each other due to electrostatic repulsion. The strong interaction can overcome this repulsion but only within a very short distance from a nucleus; beam nuclei are thus greatly accelerated in order to make such repulsion insignificant compared to the velocity of the beam nucleus.[15] Coming close alone is not enough for two nuclei to fuse: when two nuclei approach each other, they usually remain together for approximately 10−20 seconds and then part ways (not necessarily in the same composition as before the reaction) rather than form a single nucleus.[15][16] If fusion does occur, the temporary merger—termed a compound nucleus—is an excited state. To lose its excitation energy and reach a more stable state, a compound nucleus either fissions or ejects one or several neutrons,[lower-alpha 3] which carry away the energy. This occurs in approximately 10−16 seconds after the initial collision.[17][lower-alpha 4]

The beam passes through the target and reaches the next chamber, the separator; if a new nucleus is produced, it is carried with this beam.[20] In the separator, the newly produced nucleus is separated from other nuclides (that of the original beam and any other reaction products)[lower-alpha 5] and transferred to a surface-barrier detector, which stops the nucleus. The exact location of the upcoming impact on the detector is marked; also marked are its energy and the time of the arrival.[20] The transfer takes about 10−6 seconds; in order to be detected, the nucleus must survive this long.[23] The nucleus is recorded again once its decay is registered, and the location, the energy, and the time of the decay are measured.[20]

Stability of a nucleus is provided by the strong interaction. However, its range is very short; as nuclei become larger, their influence on the outermost nucleons (protons and neutrons) weakens. At the same time, the nucleus is torn apart by electrostatic repulsion between protons, as it has unlimited range.[24] Nuclei of the heaviest elements are thus theoretically predicted[25] and have so far been observed[26] to primarily decay via decay modes that are caused by such repulsion: alpha decay and spontaneous fission;[lower-alpha 6] these modes are predominant for nuclei of superheavy elements. Alpha decays are registered by the emitted alpha particles, and the decay products are easy to determine before the actual decay; if such a decay or a series of consecutive decays produces a known nucleus, the original product of a reaction can be determined arithmetically.[lower-alpha 7] Spontaneous fission, however, produces various nuclei as products, so the original nuclide cannot be determined from its daughters.[lower-alpha 8]

The information available to physicists aiming to synthesize one of the heaviest elements is thus the information collected at the detectors: location, energy, and time of arrival of a particle to the detector, and those of its decay. The physicists analyze this data and seek to conclude that it was indeed caused by a new element and could not have been caused by a different nuclide than the one claimed. Often, provided data is insufficient for a conclusion that a new element was definitely created and there is no other explanation for the observed effects; errors in interpreting data have been made.[lower-alpha 9]

History

Synthesis attempts
Main article: Isotopes of ununennium

Elements 114 to 118 (flerovium through oganesson) were discovered in "hot fusion" reactions at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. This involved bombarding the actinides plutonium through californium with calcium-48, a quasi-stable neutron-rich isotope which could be used as a projectile to produce more neutron-rich isotopes of superheavy elements.[38] (The term "hot" refers to the high excitation energy of the resulting compound nucleus.) This cannot easily be continued to element 119, because it would require a target of the next actinide einsteinium. Tens of milligrams of einsteinium would be needed for a reasonable chance of success, but only micrograms have so far been produced.[39] An attempt to make element 119 from calcium-48 and less than a microgram of einsteinium was made in 1985 at the superHILAC accelerator at Berkeley, California, but did not succeed.[40]

254
99Es
 + 48
20Ca
 → 302
119Uue
* → no atoms

More practical production of further superheavy elements requires projectiles heavier than 48Ca,[38] but this makes the reaction more symmetric[41] and gives it a smaller chance of success.[39] Attempts to synthesize element 119 push the limits of current technology, due to the decreasing cross sections of the production reactions and the probably short half-lives of produced isotopes,[42] expected to be on the order of microseconds.[1][43]

From April to September 2012, an attempt to synthesize the isotopes 295Uue and 296Uue was made by bombarding a target of berkelium-249 with titanium-50 at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany.[44][45] This reaction between 249Bk and 50Ti was predicted to be the most favorable practical reaction for formation of ununennium,[45] as it is the most asymmetric reaction available.[42] Moreover, as berkelium-249 decays to californium-249 (the next element) with a short half-life of 327 days, this allowed elements 119 and 120 to be searched for simultaneously.[41] Due to the predicted short half-lives, the GSI team used new "fast" electronics capable of registering decay events within microseconds.[45][42]

249
97Bk
 + 50
22Ti
 → 299
119Uue
* → no atoms
249
98Cf
 + 50
22Ti
 → 299
120Ubn
* → no atoms

Neither element 119 nor element 120 was observed.[46][41] The experiment was originally planned to continue to November 2012,[47] but was stopped early to make use of the 249Bk target to confirm the synthesis of tennessine (thus changing the projectiles to 48Ca).[46]

The team at RIKEN in Wakō, Japan began bombarding curium-248 targets with a vanadium-51 beam in January 2018[48] to search for element 119. Curium was chosen as a target, rather than heavier berkelium or californium, as these heavier targets are difficult to prepare.[49] The 248Cm targets were provided by Oak Ridge National Laboratory. RIKEN developed a high-intensity vanadium beam.[39] The experiment began at a cyclotron while RIKEN upgraded its linear accelerators; the upgrade was completed in 2020.[50] Bombardment may be continued with both machines until the first event is observed; the experiment is currently running intermittently for at least 100 days per year.[51][49] The RIKEN team's efforts are being financed by the Emperor of Japan.[52]

248
96Cm
 + 51
23V
 → 299
119Uue
* → no atoms yet

The produced isotopes of ununennium are expected to undergo two alpha decays to known isotopes of moscovium, 287Mc and 288Mc. This would anchor them to a known sequence of five or six further alpha decays, respectively, and corroborate their production.[48][53]

The team at the JINR plans to attempt synthesis of element 119 in the future, but a precise timeframe has not been publicly released.[54] Beams heavier than 48Ca have not been used at the JINR to produce such heavy elements, but they are actively being developed.[39]

Naming

Using Mendeleev's nomenclature for unnamed and undiscovered elements, ununennium should be known as eka-francium. Using the 1979 IUPAC recommendations, the element should be temporarily called ununennium (symbol Uue) until it is discovered, the discovery is confirmed, and a permanent name chosen.[55] Although widely used in the chemical community on all levels, from chemistry classrooms to advanced textbooks, the recommendations are mostly ignored among scientists who work theoretically or experimentally on superheavy elements, who call it "element 119", with the symbol E119, (119) or 119.[1]

Predicted properties

Nuclear stability and isotopes
A 2D graph with rectangular cells colored in black-and-white colors, spanning from the llc to the urc, with cells mostly becoming lighter closer to the latter
A chart of nuclide stability as used by the Dubna team in 2010. Characterized isotopes are shown with borders. Beyond element 118 (oganesson, the last known element), the line of known nuclides is expected to rapidly enter a region of instability, with no half-lives over one microsecond after element 121. The white ring encloses the predicted location of the island of stability.[42]
Orbitals with high azimuthal quantum number are raised in energy, eliminating what would otherwise be a gap in orbital energy corresponding to a closed proton shell at element 114, as shown in the left diagram which does not take this effect into account. This raises the next proton shell to the region around element 120, as shown in the right diagram, potentially increasing the half-lives of element 119 and 120 isotopes.[56]

The stability of nuclei decreases greatly with the increase in atomic number after curium, element 96, whose half-life is four orders of magnitude longer than that of any currently known higher-numbered element. All isotopes with an atomic number above 101 undergo radioactive decay with half-lives of less than 30 hours. No elements with atomic numbers above 82 (after lead) have stable isotopes.[57] Nevertheless, for reasons not yet well understood, there is a slight increase of nuclear stability around atomic numbers 110–114, which leads to the appearance of what is known in nuclear physics as the "island of stability". This concept, proposed by University of California professor Glenn Seaborg, explains why superheavy elements last longer than predicted.[58]

The alpha-decay half-lives predicted for 291–307Uue are on the order of microseconds. The longest alpha-decay half-life predicted is ~485 microseconds for the isotope 294Uue.[59][60][61] When factoring in all decay modes, the predicted half-lives drop further to only tens of microseconds.[1][43] Some heavier isotopes may be more stable; Fricke and Waber predicted 315Uue to be the most stable ununennium isotope in 1971.[2] This has consequences for the synthesis of ununennium, as isotopes with half-lives below one microsecond would decay before reaching the detector, and the heavier isotopes cannot be synthesised by the collision of any known usable target and projectile nuclei.[1][43] Nevertheless, new theoretical models show that the expected gap in energy between the proton orbitals 2f7/2 (filled at element 114) and 2f5/2 (filled at element 120) is smaller than expected, so that element 114 no longer appears to be a stable spherical closed nuclear shell, and this energy gap may increase the stability of elements 119 and 120. The next doubly magic nucleus is now expected to be around the spherical 306Ubb (element 122), but the expected low half-life and low production cross section of this nuclide makes its synthesis challenging.[56]

Atomic and physical

Being the first period 8 element, ununennium is predicted to be an alkali metal, taking its place in the periodic table below lithium, sodium, potassium, rubidium, caesium, and francium. Each of these elements has one valence electron in the outermost s-orbital (valence electron configuration ns1), which is easily lost in chemical reactions to form the +1 oxidation state: thus, the alkali metals are very reactive elements. Ununennium is predicted to continue the trend and have a valence electron configuration of 8s1. It is therefore expected to behave much like its lighter congeners; however, it is also predicted to differ from the lighter alkali metals in some properties.[1]

The main reason for the predicted differences between ununennium and the other alkali metals is the spin–orbit (SO) interaction—the mutual interaction between the electrons' motion and spin. The SO interaction is especially strong for the superheavy elements because their electrons move faster—at speeds comparable to the speed of light—than those in lighter atoms.[62] In ununennium atoms, it lowers the 7p and 8s electron energy levels, stabilizing the corresponding electrons, but two of the 7p electron energy levels are more stabilized than the other four.[63] The effect is called subshell splitting, as it splits the 7p subshell into more-stabilized and the less-stabilized parts. Computational chemists understand the split as a change of the second (azimuthal) quantum number ℓ from 1 to 1⁄2 and 3⁄2 for the more-stabilized and less-stabilized parts of the 7p subshell, respectively.[62][lower-alpha 10] Thus, the outer 8s electron of ununennium is stabilized and becomes harder to remove than expected, while the 7p3/2 electrons are correspondingly destabilized, perhaps allowing them to participate in chemical reactions.[1] This stabilization of the outermost s-orbital (already significant in francium) is the key factor affecting ununennium's chemistry, and causes all the trends for atomic and molecular properties of alkali metals to reverse direction after caesium.[5]

Empirical (Na–Cs, Mg–Ra) and predicted (Fr–Uhp, Ubn–Uhh) atomic radii of the alkali and alkaline earth metals from the third to the ninth period, measured in angstroms[1][64]
Empirical (Na–Cs), semi-empirical (Fr), and predicted (Uue) electron affinities of the alkali metals from the third to the eighth period, measured in electron volts.[1][64] They decrease from Li to Cs, but the Fr value, 492±10 meV, is 20 meV higher than that of Cs, and that of Uue is much higher still at 662 meV.[65]
Empirical (Na–Fr, Mg–Ra) and predicted (Uue–Uhp, Ubn–Uhh) ionization energy of the alkali and alkaline earth metals from the third to the ninth period, measured in electron volts[1][64]

Due to the stabilization of its outer 8s electron, ununennium's first ionization energy—the energy required to remove an electron from a neutral atom—is predicted to be 4.53 eV, higher than those of the known alkali metals from potassium onward. This effect is so large that unbiunium (element 121) is predicted to have a lower ionization energy of 4.45 eV, so that the alkali metal in period 8 would not have the lowest ionization energy in the period, as is true for all previous periods.[1] Ununennium's electron affinity is expected to be far greater than that of caesium and francium; indeed, ununennium is expected to have an electron affinity higher than all the alkali metals lighter than it at about 0.662 eV, close to that of cobalt (0.662 eV) and chromium (0.676 eV).[65] Relativistic effects also cause a very large drop in the polarizability of ununennium[1] to 169.7 a.u.[66] Indeed, the static dipole polarisability (αD) of ununennium, a quantity for which the impacts of relativity are proportional to the square of the element's atomic number, has been calculated to be small and similar to that of sodium.[67]

The electron of the hydrogen-like ununennium atom—oxidized so it has only one electron, Uue118+—is predicted to move so quickly that its mass is 1.99 times that of a non-moving electron, a consequence of relativistic effects. For comparison, the figure for hydrogen-like francium is 1.29 and the figure for hydrogen-like caesium is 1.091.[62] According to simple extrapolations of relativity laws, that indirectly indicates the contraction of the atomic radius[62] to around 240 pm,[1] very close to that of rubidium (247 pm); the metallic radius is also correspondingly lowered to 260 pm.[1] The ionic radius of Uue+ is expected to be 180 pm.[1]

Ununennium is predicted to have a melting point between 0 °C and 30 °C: thus it may be a liquid at room temperature.[6] It is not known whether this continues the trend of decreasing melting points down the group, as caesium's melting point is 28.5 °C and francium's is estimated to be around 8.0 °C.[68] The boiling point of ununennium is expected to be around 630 °C, similar to that of francium, estimated to be around 620 °C; this is lower than caesium's boiling point of 671 °C.[2][68] The density of ununennium has been variously predicted to be between 3 and 4 g/cm3, continuing the trend of increasing density down the group: the density of francium is estimated at 2.48 g/cm3, and that of caesium is known to be 1.93 g/cm3.[2][3][68]

Chemical
Bond lengths and bond-dissociation energies of alkali metal dimers. Data for Fr2 and Uue2 are predicted.[69]
Dimer Bond length
(Å)		 Bond-dissociation
energy (kJ/mol)
Li2 2.673 101.9
Na2 3.079 72.04
K2 3.924 53.25
Rb2 4.210 47.77
Cs2 4.648 43.66
Fr2 ~ 4.61 ~ 42.1
Uue2 ~ 4.27 ~ 53.4

The chemistry of ununennium is predicted to be similar to that of the alkali metals,[1] but it would probably behave more like potassium[70] or rubidium[1] than caesium or francium. This is due to relativistic effects, as in their absence periodic trends would predict ununennium to be even more reactive than caesium and francium. This lowered reactivity is due to the relativistic stabilization of ununennium's valence electron, increasing ununennium's first ionization energy and decreasing the metallic and ionic radii;[70] this effect is already seen for francium.[1]

The chemistry of ununennium in the +1-oxidation state should be more similar to the chemistry of rubidium than to that of francium. On the other hand, the ionic radius of the Uue+ ion is predicted to be larger than that of Rb+, because the 7p orbitals are destabilized and are thus larger than the p-orbitals of the lower shells. Ununennium may also show the +3 oxidation state,[1] which is not seen in any other alkali metal,[71] in addition to the +1 oxidation state that is characteristic of the other alkali metals and is also the main oxidation state of all the known alkali metals: this is because of the destabilization and expansion of the 7p3/2 spinor, causing its outermost electrons to have a lower ionization energy than what would otherwise be expected.[1][71] The 7p3/2 spinor's chemical activity has been suggested to make the +5 oxidation state possible in [UueF6]−, analogous to [SbF6]− or [BrF6]−. The analogous francium(V) compound, [FrF6]−, might also be achievable, but is not experimentally known.[4]

Many ununennium compounds are expected to have a large covalent character, due to the involvement of the 7p3/2 electrons in the bonding: this effect is also seen to a lesser extent in francium, which shows some 6p3/2 contribution to the bonding in francium superoxide (FrO2).[62] Thus, instead of ununennium being the most electropositive element, as a simple extrapolation would seem to indicate, caesium instead retains this position, with ununennium's electronegativity most likely being close to sodium's (0.93 on the Pauling scale).[5] The standard reduction potential of the Uue+/Uue couple is predicted to be −2.9 V, the same as that of the Fr+/Fr couple and just over that of the K+/K couple at −2.931 V.[6]

Bond lengths and bond-dissociation energies of MAu (M = an alkali metal). All data are predicted, except for the bond-dissociation energies of KAu, RbAu, and CsAu.[5]
Compound Bond length
(Å)		 Bond-dissociation
energy (kJ/mol)
KAu 2.856 2.75
RbAu 2.967 2.48
CsAu 3.050 2.53
FrAu 3.097 2.75
UueAu 3.074 2.44

In the gas phase, and at very low temperatures in the condensed phase, the alkali metals form covalently bonded diatomic molecules. The metal–metal bond lengths in these M2 molecules increase down the group from Li2 to Cs2, but then decrease after that to Uue2, due to the aforementioned relativistic effects that stabilize the 8s orbital. The opposite trend is shown for the metal–metal bond-dissociation energies. The Uue–Uue bond should be slightly stronger than the K–K bond.[5][69] From these M2 dissociation energies, the enthalpy of sublimation (ΔHsub) of ununennium is predicted to be 94 kJ/mol (the value for francium should be around 77 kJ/mol).[5]

The UueF molecule is expected to have a significant covalent character owing to the high electron affinity of ununennium. The bonding in UueF is predominantly between a 7p orbital on ununennium and a 2p orbital on fluorine, with lesser contributions from the 2s orbital of fluorine and the 8s, 6dz2, and the two other 7p orbitals of ununennium. This is very different from the behaviour of s-block elements, as well as gold and mercury, in which the s-orbitals (sometimes mixed with d-orbitals) are the ones participating in the bonding. The Uue–F bond is relativistically expanded due to the splitting of the 7p orbital into 7p1/2 and 7p3/2 spinors, forcing the bonding electrons into the largest orbital measured by radial extent: a similar expansion in bond length is found in the hydrides AtH and TsH.[72] The Uue–Au bond should be the weakest of all bonds between gold and an alkali metal, but should still be stable. This gives extrapolated medium-sized adsorption enthalpies (−ΔHads) of 106 kJ/mol on gold (the francium value should be 136 kJ/mol), 76 kJ/mol on platinum, and 63 kJ/mol on silver, the smallest of all the alkali metals, that demonstrate that it would be feasible to study the chromatographic adsorption of ununennium onto surfaces made of noble metals.[5] The enthalpy of adsorption of ununennium on a Teflon surface is predicted to be 17.6 kJ/mol, which would be the lowest among the alkali metals.[66] The ΔHsub and −ΔHads values for the alkali metals change in opposite directions as atomic number increases.[5]

See also

Notes
  1. In nuclear physics, an element is called heavy if its atomic number is high; lead (element 82) is one example of such a heavy element. The term "superheavy elements" typically refers to elements with atomic number greater than 103 (although there are other definitions, such as atomic number greater than 100[9] or 112;[10] sometimes, the term is presented an equivalent to the term "transactinide", which puts an upper limit before the beginning of the hypothetical superactinide series).[11] Terms "heavy isotopes" (of a given element) and "heavy nuclei" mean what could be understood in the common language—isotopes of high mass (for the given element) and nuclei of high mass, respectively.
  2. In 2009, a team at JINR led by Oganessian published results of their attempt to create hassium in a symmetric 136Xe + 136Xe reaction. They failed to observe a single atom in such a reaction, putting the upper limit on the cross section, the measure of probability of a nuclear reaction, as 2.5 pb.[12] In comparison, the reaction that resulted in hassium discovery, 208Pb + 58Fe, had a cross section of ~20 pb (more specifically, 19+19
    −11     pb), as estimated by the discoverers.[13]
  3. The greater the excitation energy, the more neutrons are ejected. If the excitation energy is lower than energy binding each neutron to the rest of the nucleus, neutrons are not emitted; instead, the compound nucleus de-excites by emitting a gamma ray.[17]
  4. The definition by the IUPAC/IUPAP Joint Working Party states that a chemical element can only be recognized as discovered if a nucleus of it has not decayed within 10−14 seconds. This value was chosen as an estimate of how long it takes a nucleus to acquire its outer electrons and thus display its chemical properties.[18] This figure also marks the generally accepted upper limit for lifetime of a compound nucleus.[19]
  5. This separation is based on that the resulting nuclei move past the target more slowly then the unreacted beam nuclei. The separator contains electric and magnetic fields whose effects on a moving particle cancel out for a specific velocity of a particle.[21] Such separation can also be aided by a time-of-flight measurement and a recoil energy measurement; a combination of the two may allow to estimate the mass of a nucleus.[22]
  6. Not all decay modes are caused by electrostatic repulsion. For example, beta decay is caused by the weak interaction.[27]
  7. Since mass of a nucleus is not measured directly but is rather calculated from that of another nucleus, such measurement is called indirect. Direct measurements are also possible, but for the most part they have remained unavailable for heaviest nuclei.[28] The first direct measurement of mass of a superheavy nucleus was reported in 2018 at LBNL.[29] Mass was determined from the location of a nucleus after the transfer (the location helps determine its trajectory, which is linked to the mass-to-charge ratio of the nucleus, since the transfer was done in presence of a magnet).[30]
  8. Spontaneous fission was discovered by Soviet physicist Georgy Flerov,[31] a leading scientist at JINR, and thus it was a "hobbyhorse" for the facility.[32] In contrast, the LBL scientists believed fission information was not sufficient for a claim of synthesis of an element. They believed spontaneous fission had not been studied enough to use it for identification of a new element, since there was a difficulty of establishing that a compound nucleus had only ejected neutrons and not charged particles like protons or alpha particles.[19] They thus preferred to link new isotopes to the already known ones by successive alpha decays.[31]
  9. For instance, element 102 was mistakenly identified in 1957 at the Nobel Institute of Physics in Stockholm, Stockholm County, Sweden.[33] There were no earlier definitive claims of creation of this element, and the element was assigned a name by its Swedish, American, and British discoverers, nobelium. It was later shown that the identification was incorrect.[34] The following year, LBNL was unable to reproduce the Swedish results and announced instead their synthesis of the element; that claim was also disproved later.[34] JINR insisted that they were the first to create the element and suggested a name of their own for the new element, joliotium;[35] the Soviet name was also not accepted (JINR later referred to the naming of element 102 as "hasty").[36] The name "nobelium" remained unchanged on account of its widespread usage.[37]
  10. The quantum number corresponds to the letter in the electron orbital name: 0 to s, 1 to p, 2 to d, etc. See azimuthal quantum number for more information.

References
  1. Hoffman, Darleane C.; Lee, Diana M.; Pershina, Valeria (2006). "Transactinides and the future elements". In Morss; Edelstein, Norman M.; Fuger, Jean (eds.). The Chemistry of the Actinide and Transactinide Elements (3rd ed.). Dordrecht, The Netherlands: Springer Science+Business Media. ISBN 978-1-4020-3555-5.
  2. Fricke, B.; Waber, J. T. (1971). "Theoretical Predictions of the Chemistry of Superheavy Elements" (PDF). Actinides Reviews. 1: 433–485. Retrieved 7 August 2013.
  3. Bonchev, Danail; Kamenska, Verginia (1981). "Predicting the Properties of the 113–120 Transactinide Elements". Journal of Physical Chemistry. American Chemical Society. 85 (9): 1177–1186. doi:10.1021/j150609a021.
  4. Cao, Chang-Su; Hu, Han-Shi; Schwarz, W. H. Eugen; Li, Jun (2022). "Periodic Law of Chemistry Overturns for Superheavy Elements". ChemRxiv (preprint). doi:10.26434/chemrxiv-2022-l798p. Retrieved 16 November 2022.
  5. Pershina, V.; Borschevsky, A.; Anton, J. (20 February 2012). "Fully relativistic study of intermetallic dimers of group-1 elements K through element 119 and prediction of their adsorption on noble metal surfaces". Chemical Physics. Elsevier. 395: 87–94. Bibcode:2012CP....395...87P. doi:10.1016/j.chemphys.2011.04.017. This article gives the Mulliken electronegativity as 2.72, which has been converted to the Pauling scale via χP = 1.35χM1/2 − 1.37.
  6. Fricke, Burkhard (1975). "Superheavy elements: a prediction of their chemical and physical properties". Recent Impact of Physics on Inorganic Chemistry. Structure and Bonding. 21: 89–144. doi:10.1007/BFb0116498. ISBN 978-3-540-07109-9. Retrieved 4 October 2013.
  7. Seaborg, Glenn T. (1969). "Prospects for further considerable extension of the periodic table" (PDF). Journal of Chemical Education. 46 (10): 626–634. Bibcode:1969JChEd..46..626S. doi:10.1021/ed046p626. Retrieved 22 February 2018.
  8. Wakhle, A.; Simenel, C.; Hinde, D. J.; et al. (2015). Simenel, C.; Gomes, P. R. S.; Hinde, D. J.; et al. (eds.). "Comparing Experimental and Theoretical Quasifission Mass Angle Distributions". European Physical Journal Web of Conferences. 86: 00061. Bibcode:2015EPJWC..8600061W. doi:10.1051/epjconf/20158600061. ISSN 2100-014X.
  9. Krämer, K. (2016). "Explainer: superheavy elements". Chemistry World. Retrieved 2020-03-15.
  10. "Discovery of Elements 113 and 115". Lawrence Livermore National Laboratory. Archived from the original on 2015-09-11. Retrieved 2020-03-15.
  11. Eliav, E.; Kaldor, U.; Borschevsky, A. (2018). "Electronic Structure of the Transactinide Atoms". In Scott, R. A. (ed.). Encyclopedia of Inorganic and Bioinorganic Chemistry. John Wiley & Sons. pp. 1–16. doi:10.1002/9781119951438.eibc2632. ISBN 978-1-119-95143-8. S2CID 127060181.
  12. Oganessian, Yu. Ts.; Dmitriev, S. N.; Yeremin, A. V.; et al. (2009). "Attempt to produce the isotopes of element 108 in the fusion reaction 136Xe + 136Xe". Physical Review C. 79 (2): 024608. doi:10.1103/PhysRevC.79.024608. ISSN 0556-2813.
  13. Münzenberg, G.; Armbruster, P.; Folger, H.; et al. (1984). "The identification of element 108" (PDF). Zeitschrift für Physik A. 317 (2): 235–236. Bibcode:1984ZPhyA.317..235M. doi:10.1007/BF01421260. S2CID 123288075. Archived from the original (PDF) on 7 June 2015. Retrieved 20 October 2012.
  14. Subramanian, S. (2019). "Making New Elements Doesn't Pay. Just Ask This Berkeley Scientist". Bloomberg Businessweek. Archived from the original on November 14, 2020. Retrieved 2020-01-18.
  15. Ivanov, D. (2019). "Сверхтяжелые шаги в неизвестное" [Superheavy steps into the unknown]. N+1 (in Russian). Retrieved 2020-02-02.
  16. Hinde, D. (2014). "Something new and superheavy at the periodic table". The Conversation. Retrieved 2020-01-30.
  17. Krása, A. (2010). "Neutron Sources for ADS" (PDF). Czech Technical University in Prague. pp. 4–8. S2CID 28796927. Archived from the original (PDF) on 2019-03-03. Retrieved October 20, 2019.
  18. Wapstra, A. H. (1991). "Criteria that must be satisfied for the discovery of a new chemical element to be recognized" (PDF). Pure and Applied Chemistry. 63 (6): 883. doi:10.1351/pac199163060879. ISSN 1365-3075. S2CID 95737691. Retrieved 2020-08-28.
  19. Hyde, E. K.; Hoffman, D. C.; Keller, O. L. (1987). "A History and Analysis of the Discovery of Elements 104 and 105". Radiochimica Acta. 42 (2): 67–68. doi:10.1524/ract.1987.42.2.57. ISSN 2193-3405. S2CID 99193729.
  20. Chemistry World (2016). "How to Make Superheavy Elements and Finish the Periodic Table [Video]". Scientific American. Retrieved 2020-01-27.
  21. Hoffman, Ghiorso & Seaborg 2000, p. 334.
  22. Hoffman, Ghiorso & Seaborg 2000, p. 335.
  23. Zagrebaev, Karpov & Greiner 2013, p. 3.
  24. Beiser 2003, p. 432.
  25. Staszczak, A.; Baran, A.; Nazarewicz, W. (2013). "Spontaneous fission modes and lifetimes of superheavy elements in the nuclear density functional theory". Physical Review C. 87 (2): 024320–1. arXiv:1208.1215. Bibcode:2013PhRvC..87b4320S. doi:10.1103/physrevc.87.024320. ISSN 0556-2813. S2CID 118134429.
  26. Audi, G.; Kondev, F. G.; Wang, M.; et al. (2017). "The NUBASE2016 evaluation of nuclear properties". Chinese Physics C. 41 (3): 030001-128–030001-138. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.
  27. Beiser 2003, p. 439.
  28. Oganessian, Yu. Ts.; Rykaczewski, K. P. (2015). "A beachhead on the island of stability". Physics Today. 68 (8): 32–38. Bibcode:2015PhT....68h..32O. doi:10.1063/PT.3.2880. ISSN 0031-9228. OSTI 1337838. S2CID 119531411.
  29. Grant, A. (2018). "Weighing the heaviest elements". Physics Today. doi:10.1063/PT.6.1.20181113a. S2CID 239775403.
  30. Howes, L. (2019). "Exploring the superheavy elements at the end of the periodic table". Chemical & Engineering News. Retrieved 2020-01-27.
  31. Robinson, A. E. (2019). "The Transfermium Wars: Scientific Brawling and Name-Calling during the Cold War". Distillations. Retrieved 2020-02-22.
  32. "Популярная библиотека химических элементов. Сиборгий (экавольфрам)" [Popular library of chemical elements. Seaborgium (eka-tungsten)]. n-t.ru (in Russian). Retrieved 2020-01-07. Reprinted from "Экавольфрам" [Eka-tungsten]. Популярная библиотека химических элементов. Серебро — Нильсборий и далее [Popular library of chemical elements. Silver through nielsbohrium and beyond] (in Russian). Nauka. 1977.
  33. "Nobelium – Element information, properties and uses | Periodic Table". Royal Society of Chemistry. Retrieved 2020-03-01.
  34. Kragh 2018, pp. 38–39.
  35. Kragh 2018, p. 40.
  36. Ghiorso, A.; Seaborg, G. T.; Oganessian, Yu. Ts.; et al. (1993). "Responses on the report 'Discovery of the Transfermium elements' followed by reply to the responses by Transfermium Working Group" (PDF). Pure and Applied Chemistry. 65 (8): 1815–1824. doi:10.1351/pac199365081815. S2CID 95069384. Archived (PDF) from the original on 25 November 2013. Retrieved 7 September 2016.
  37. Commission on Nomenclature of Inorganic Chemistry (1997). "Names and symbols of transfermium elements (IUPAC Recommendations 1997)" (PDF). Pure and Applied Chemistry. 69 (12): 2471–2474. doi:10.1351/pac199769122471.
  38. Folden III, C. M.; Mayorov, D. A.; et al. (2013). "Prospects for the discovery of the next new element: Influence of projectiles with Z > 20". Journal of Physics: Conference Series. IOP Publishing Ltd. 420 (1). 012007. arXiv:1209.0498. Bibcode:2013JPhCS.420a2007F. doi:10.1088/1742-6596/420/1/012007. S2CID 119275964.
  39. Gates, J.; Pore, J.; Crawford, H.; Shaughnessy, D.; Stoyer, M. A. (25 October 2022). "The Status and Ambitions of the US Heavy Element Program". osti.gov. doi:10.2172/1896856. OSTI 1896856. S2CID 253391052. Retrieved 13 November 2022.
  40. Lougheed, R.; Landrum, J.; Hulet, E.; et al. (3 June 1985). "Search for superheavy elements using the 48Ca + 254Esg reaction". Physical Review C (published 1 November 1985). 32 (5): 1760–1763. Bibcode:1985PhRvC..32.1760L. doi:10.1103/PhysRevC.32.1760. PMID 9953034. Retrieved 21 March 2022.
  41. Khuyagbaatar, J.; Yakushev, A.; Düllmann, Ch. E.; et al. (2020). "Search for elements 119 and 120" (PDF). Physical Review C. 102 (6). 064602. Bibcode:2020PhRvC.102f4602K. doi:10.1103/PhysRevC.102.064602. hdl:1885/289860. S2CID 229401931. Retrieved 25 January 2021.
  42. Zagrebaev, Karpov & Greiner 2013.
  43. Hofmann, Sigurd (2013). Greiner, Walter (ed.). Overview and Perspectives of SHE Research at GSI SHIP. pp. 23–32. doi:10.1007/978-3-319-00047-3. ISBN 978-3-319-00046-6.
  44. Modern alchemy: Turning a line, The Economist, May 12, 2012.
  45. DÜLLMANN, CHRISTOPH E. (2013). "Superheavy Element Research at Tasca at Gsi". Fission and Properties of Neutron-Rich Nuclei. WORLD SCIENTIFIC: 271–277. doi:10.1142/9789814525435_0029. ISBN 978-981-4525-42-8. Retrieved 21 March 2022.
  46. http://asrc.jaea.go.jp/soshiki/gr/chiba_gr/workshop3/&Yakushev.pdf
  47. "Search for element 119: Christoph E. Düllmann for the TASCA E119 collaboration" (PDF). Archived from the original (PDF) on 2016-03-04. Retrieved 2015-09-15.
  48. Sakai, Hideyuki; Haba, Hiromitsu; Morimoto, Kouji; Sakamoto, Naruhiko (9 December 2022). "Facility upgrade for superheavy-element research at RIKEN". The European Physical Journal A. 58 (238): 238. Bibcode:2022EPJA...58..238S. doi:10.1140/epja/s10050-022-00888-3. PMC 9734366. PMID 36533209.
  49. Sakai, Hideyuki (27 February 2019). "Search for a New Element at RIKEN Nishina Center" (PDF). infn.it. Retrieved 17 December 2019.
  50. Sakurai, Hiroyoshi (1 April 2020). "Greeting | RIKEN Nishina Center". With the completion of the upgrade of the linear accelerator and BigRIPS at the beginning of 2020, the RNC aims to synthesize new elements from element 119 and beyond.
  51. Ball, P. (2019). "Extreme chemistry: experiments at the edge of the periodic table" (PDF). Nature. 565 (7741): 552–555. Bibcode:2019Natur.565..552B. doi:10.1038/d41586-019-00285-9. ISSN 1476-4687. PMID 30700884. S2CID 59524524. We started the search for element 119 last June," says RIKEN researcher Hideto En'yo. "It will certainly take a long time — years and years — so we will continue the same experiment intermittently for 100 or more days per year, until we or somebody else discovers it.
  52. Chapman, Kit; Turner, Kristy (13 February 2018). "The hunt is on". Education in Chemistry. Royal Society of Chemistry. Retrieved 28 June 2019. The hunt for element 113 was almost abandoned because of lack of resources, but this time Japan's emperor is bankrolling Riken's efforts to extend the periodic table to its eighth row.
  53. Oganessian, Yu. Ts.; Utyonkov, V. K.; Kovrizhnykh, N. D.; et al. (2022). "New isotope 286Mc produced in the 243Am+48Ca reaction". Physical Review C. 106 (64306): 064306. Bibcode:2022PhRvC.106f4306O. doi:10.1103/PhysRevC.106.064306. S2CID 254435744.
  54. Joint Institute for Nuclear Research (24 July 2021). "JINR presented largest Periodic Table to Dubna". jinr.ru. Joint Institute for Nuclear Research. Retrieved 27 January 2022.
  55. Chatt, J. (1979). "Recommendations for the naming of elements of atomic numbers greater than 100". Pure and Applied Chemistry. 51 (2): 381–384. doi:10.1351/pac197951020381.
  56. Kratz, J. V. (5 September 2011). The Impact of Superheavy Elements on the Chemical and Physical Sciences (PDF). 4th International Conference on the Chemistry and Physics of the Transactinide Elements. Retrieved 27 August 2013.
  57. de Marcillac, Pierre; Coron, Noël; Dambier, Gérard; et al. (2003). "Experimental detection of α-particles from the radioactive decay of natural bismuth". Nature. 422 (6934): 876–878. Bibcode:2003Natur.422..876D. doi:10.1038/nature01541. PMID 12712201. S2CID 4415582.
  58. Considine, Glenn D.; Kulik, Peter H. (2002). Van Nostrand's scientific encyclopedia (9th ed.). Wiley-Interscience. ISBN 978-0-471-33230-5. OCLC 223349096.
  59. Chowdhury, P. Roy; Samanta, C. & Basu, D. N. (2007). "Predictions of alpha decay half lives of heavy and superheavy elements". Nucl. Phys. A. 789 (1–4): 142–154. arXiv:nucl-th/0703086. Bibcode:2007NuPhA.789..142S. CiteSeerX 10.1.1.264.8177. doi:10.1016/j.nuclphysa.2007.04.001. S2CID 7496348.
  60. Chowdhury, P. Roy; Samanta, C. & Basu, D. N. (2008). "Search for long lived heaviest nuclei beyond the valley of stability". Phys. Rev. C. 77 (4). 044603. arXiv:0802.3837. Bibcode:2008PhRvC..77d4603C. doi:10.1103/PhysRevC.77.044603. S2CID 119207807.
  61. Chowdhury, P. Roy; Samanta, C. & Basu, D. N. (2008). "Nuclear half-lives for α -radioactivity of elements with 100 ≤ Z ≤ 130". Atomic Data and Nuclear Data Tables. 94 (6): 781–806. arXiv:0802.4161. Bibcode:2008ADNDT..94..781C. doi:10.1016/j.adt.2008.01.003. S2CID 96718440.
  62. Thayer, John S. (2010). "Relativistic Effects and the Chemistry of the Heavier Main Group Elements". In Maria, Barysz; Ishikawa, Yasuyuki (eds.). Relativistic Methods for Chemists. Challenges and Advances in Computational Chemistry and Physics. Vol. 10. Springer Netherlands. pp. 63–67, 81, 84. doi:10.1007/978-1-4020-9975-5_2. ISBN 978-1-4020-9974-8.
  63. Fægri Jr., Knut; Saue, Trond (2001). "Diatomic molecules between very heavy elements of group 13 and group 17: A study of relativistic effects on bonding". The Journal of Chemical Physics. 115 (6): 2456. Bibcode:2001JChPh.115.2456F. doi:10.1063/1.1385366.
  64. Pyykkö, Pekka (2011). "A suggested periodic table up to Z ≤ 172, based on Dirac–Fock calculations on atoms and ions". Physical Chemistry Chemical Physics. 13 (1): 161–168. Bibcode:2011PCCP...13..161P. doi:10.1039/c0cp01575j. PMID 20967377. S2CID 31590563.
  65. Landau, Arie; Eliav, Ephraim; Ishikawa, Yasuyuki; Kador, Uzi (25 May 2001). "Benchmark calculations of electron affinities of the alkali atoms sodium to eka-francium (element 119)". Journal of Chemical Physics. 115 (6): 2389–2392. Bibcode:2001JChPh.115.2389L. doi:10.1063/1.1386413. Retrieved 15 September 2015.
  66. Borschevsky, A.; Pershina, V.; Eliav, E.; Kaldor, U. (22 March 2013). "Ab initio studies of atomic properties and experimental behavior of element 119 and its lighter homologs" (PDF). The Journal of Chemical Physics. 138 (12). 124302. Bibcode:2013JChPh.138l4302B. doi:10.1063/1.4795433. PMID 23556718.
  67. Lim, Ivan S.; Pernpointner, Markus; Seth, Michael; et al. (1999). "Relativistic coupled-cluster static dipole polarizabilities of the alkali metals from Li to element 119". Physical Review A. 60 (4). 2822. Bibcode:1999PhRvA..60.2822L. doi:10.1103/PhysRevA.60.2822.
  68. Lavrukhina, Avgusta Konstantinovna; Pozdnyakov, Aleksandr Aleksandrovich (1970). Analytical Chemistry of Technetium, Promethium, Astatine, and Francium. Translated by R. Kondor. Ann Arbor–Humphrey Science Publishers. p. 269. ISBN 978-0-250-39923-9.
  69. Jones, Cameron; Mountford, Philip; Stasch, Andreas; Blake, Matthew P. (22 June 2015). "s-block Metal-Metal Bonds". In Liddle, Stephen T. (ed.). Molecular Metal-Metal Bonds: Compounds, Synthesis, Properties. John Wiley and Sons. pp. 23–24. ISBN 9783527335411.
  70. Seaborg (c. 2006). "transuranium element (chemical element)". Encyclopædia Britannica. Retrieved 2010-03-16.
  71. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. ISBN 978-0-08-037941-8.
  72. Miranda, P. S.; Mendes, A. P. S.; Gomes, J. S.; et al. (2012). "Ab Initio Correlated All Electron Dirac-Fock Calculations for Eka-Francium Fluoride (E119F)". Journal of the Brazilian Chemical Society. 23 (6): 1104–1113. doi:10.1590/S0103-50532012000600015. Retrieved 14 January 2018.

Bibliography
  • The dictionary definition of ununennium at Wiktionary
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