Wikipedia

Dubnium

"Hahnium" redirects here. Not to be confused withHafnium.
For the node.js release labeled "Dubnium", seenode.js § Releases.

Dubniumis asynthetic chemical element;it hassymbolDbandatomic number105. It is highly radioactive: the most stable knownisotope,dubnium-268, has ahalf-lifeof about 16 hours. This greatly limits extended research on the element.

Dubnium,105Db
Dubnium
Pronunciation
Mass number[268]
Dubnium in theperiodic 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
Ta
↑
Db
↓
—
rutherfordium←dubnium→seaborgium
Atomic number(Z)105
Groupgroup 5
Periodperiod 7
Blockd-block
Electron configuration[Rn] 5f146d37s2[3]
Electrons per shell2, 8, 18, 32, 32, 11, 2
Physical properties
PhaseatSTPsolid(predicted)[4]
Density(nearr.t.)21.6 g/cm3(predicted)[5][6]
Atomic properties
Oxidation states(+3), (+4),+5[3][7](parenthesized:prediction)
Ionization energies
  • 1st: 665 kJ/mol
  • 2nd: 1547 kJ/mol
  • 3rd: 2378 kJ/mol
  • (more)(all but first estimated)[3]
Atomic radiusempirical: 139pm(estimated)[3]
Covalent radius149 pm(estimated)[8]
Other properties
Natural occurrencesynthetic
Crystal structure​body-centered cubic(bcc)(predicted)[4]
Body-centered cubic crystal structure for dubnium
CAS Number53850-35-4
History
NamingafterDubna,Moscow Oblast,Russia, site ofJoint Institute for Nuclear Research
Discoveryindependently by theLawrence Berkeley Laboratoryand the Joint Institute for Nuclear Research(1970)
Isotopes of dubnium
Main isotopes[9] Decay
abun­dance half-life(t1/2) mode pro­duct
262Db synth 34 s[10][11] α67% 258Lr
SF33% –
263Db synth 27 s[11] SF56% –
α41% 259Lr
ε3% 263mRf
266Db synth 11 min[12] SF –
ε 266Rf
267Db synth 1.4 h[12] SF –
268Db synth 16 h[13] SF –
ε 268Rf
α[13] 264Lr
270Db synth 1 h[14] SF17% –
α83% 266Lr
Category: Dubnium
|references

Dubnium does not occur naturally on Earth and is produced artificially. The SovietJoint Institute for Nuclear Research(JINR) claimed the first discovery of the element in 1968, followed by the AmericanLawrence Berkeley Laboratoryin 1970. Both teams proposed their names for the new element and used them without formal approval. The long-standing dispute was resolved in 1993 by an official investigation of the discovery claims by the Transfermium Working Group, formed by theInternational Union of Pure and Applied Chemistryand theInternational Union of Pure and Applied Physics,resulting in credit for the discovery being officially shared between both teams. The element was formally nameddubniumin 1997 after the town ofDubna,the site of the JINR.

Theoretical research establishes dubnium as a member ofgroup 5in the 6d series oftransition metals,placing it undervanadium,niobium,andtantalum.Dubnium should share most properties, such as its valenceelectron configurationand having a dominant +5 oxidation state, with the other group 5 elements, with a few anomalies due torelativistic effects.A limited investigation of dubnium chemistry has confirmed this.

Introduction

edit
This section is an excerpt fromSuperheavy element § Introduction.[edit]

Synthesis of superheavy nuclei

edit
A graphic depiction of anuclear fusionreaction. Two nuclei fuse into one, emitting aneutron.Reactions that created new elements to this moment were similar, with the only possible difference that several singular neutrons sometimes were released, or none at all.

A superheavy[a]atomic nucleusis created in a nuclear reaction that combines two other nuclei of unequal size[b]into one; roughly, the more unequal the two nuclei in terms ofmass,the greater the possibility that the two react.[20]The material made of the heavier nuclei is made into a target, which is then bombarded by thebeamof lighter nuclei. Two nuclei can onlyfuseinto one if they approach each other closely enough; normally, nuclei (all positively charged) repel each other due toelectrostatic repulsion.Thestrong interactioncan overcome this repulsion but only within a very short distance from a nucleus; beam nuclei are thus greatlyacceleratedin order to make such repulsion insignificant compared to the velocity of the beam nucleus.[21]The energy applied to the beam nuclei to accelerate them can cause them to reach speeds as high as one-tenth of thespeed of light.However, if too much energy is applied, the beam nucleus can fall apart.[21]

Coming close enough alone is not enough for two nuclei to fuse: when two nuclei approach each other, they usually remain together for about 10−20seconds and then part ways (not necessarily in the same composition as before the reaction) rather than form a single nucleus.[21][22]This happens because during the attempted formation of a single nucleus, electrostatic repulsion tears apart the nucleus that is being formed.[21]Each pair of a target and a beam is characterized by itscross section—the probability that fusion will occur if two nuclei approach one another expressed in terms of the transverse area that the incident particle must hit in order for the fusion to occur.[c]This fusion may occur as a result of the quantum effect in which nuclei cantunnelthrough electrostatic repulsion. If the two nuclei can stay close for past that phase, multiple nuclear interactions result in redistribution of energy and an energy equilibrium.[21]

External videos
Visualizationof unsuccessful nuclear fusion, based on calculations from theAustralian National University[24]

The resulting merger is anexcited state[25]—termed acompound nucleus—and thus it is very unstable.[21]To reach a more stable state, the temporary merger mayfissionwithout formation of a more stable nucleus.[26]Alternatively, the compound nucleus may eject a fewneutrons,which would carry away the excitation energy; if the latter is not sufficient for a neutron expulsion, the merger would produce agamma ray.This happens in about 10−16seconds after the initial nuclear collision and results in creation of a more stable nucleus.[26]The definition by theIUPAC/IUPAP Joint Working Party(JWP) states that achemical elementcan only be recognized as discovered if a nucleus of it has notdecayedwithin 10−14seconds. This value was chosen as an estimate of how long it takes a nucleus to acquireelectronsand thus display its chemical properties.[27][d]

Decay and detection

edit

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.[29]In the separator, the newly produced nucleus is separated from other nuclides (that of the original beam and any other reaction products)[e]and transferred to asurface-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.[29]The transfer takes about 10−6seconds; in order to be detected, the nucleus must survive this long.[32]The nucleus is recorded again once its decay is registered, and the location, theenergy,and the time of the decay are measured.[29]

Stability of a nucleus is provided by the strong interaction. However, its range is very short; as nuclei become larger, its influence on the outermostnucleons(protonsand neutrons) weakens. At the same time, the nucleus is torn apart by electrostatic repulsion between protons, and its range is not limited.[33]Totalbinding energyprovided by the strong interaction increases linearly with the number of nucleons, whereas electrostatic repulsion increases with the square of the atomic number, i.e. the latter grows faster and becomes increasingly important for heavy and superheavy nuclei.[34][35]Superheavy nuclei are thus theoretically predicted[36]and have so far been observed[37]to predominantly decay via decay modes that are caused by such repulsion:alpha decayandspontaneous fission.[f]Almost all alpha emitters have over 210 nucleons,[39]and the lightest nuclide primarily undergoing spontaneous fission has 238.[40]In both decay modes, nuclei are inhibited from decaying by correspondingenergy barriersfor each mode, but they can be tunneled through.[34][35]

Scheme of an apparatus for creation of superheavy elements, based on the Dubna Gas-Filled Recoil Separator set up in theFlerov Laboratory of Nuclear Reactionsin JINR. The trajectory within the detector and the beam focusing apparatus changes because of adipole magnetin the former andquadrupole magnetsin the latter.[41]

Alpha particles are commonly produced in radioactive decays because mass of an alpha particle per nucleon is small enough to leave some energy for the alpha particle to be used as kinetic energy to leave the nucleus.[42]Spontaneous fission is caused by electrostatic repulsion tearing the nucleus apart and produces various nuclei in different instances of identical nuclei fissioning.[35]As the atomic number increases, spontaneous fission rapidly becomes more important: spontaneous fission partial half-lives decrease by 23 orders of magnitude fromuranium(element 92) tonobelium(element 102),[43]and by 30 orders of magnitude fromthorium(element 90) tofermium(element 100).[44]The earlierliquid drop modelthus suggested that spontaneous fission would occur nearly instantly due to disappearance of thefission barrierfor nuclei with about 280 nucleons.[35][45]The laternuclear shell modelsuggested that nuclei with about 300 nucleons would form anisland of stabilityin which nuclei will be more resistant to spontaneous fission and will primarily undergo alpha decay with longer half-lives.[35][45]Subsequent discoveries suggested that the predicted island might be further than originally anticipated; they also showed that nuclei intermediate between the long-lived actinides and the predicted island are deformed, and gain additional stability from shell effects.[46]Experiments on lighter superheavy nuclei,[47]as well as those closer to the expected island,[43]have shown greater than previously anticipated stability against spontaneous fission, showing the importance of shell effects on nuclei.[g]

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 easily determined.[h](That all decays within a decay chain were indeed related to each other is established by the location of these decays, which must be in the same place.)[29]The known nucleus can be recognized by the specific characteristics of decay it undergoes such as decay energy (or more specifically, thekinetic energyof the emitted particle).[i]Spontaneous fission, however, produces various nuclei as products, so the original nuclide cannot be determined from its daughters.[j]

The information available to physicists aiming to synthesize a superheavy element 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.[k]

Discovery

edit

Background

edit

Uranium,element 92, is the heaviest element to occur in significant quantities in nature; heavier elements can only be practically produced by synthesis. The first synthesis of a new element—neptunium,element 93—was achieved in 1940 by a team of researchers in the United States.[58]In the following years, American scientists synthesized the elements up tomendelevium,element 101, which was synthesized in 1955. Fromelement 102,the priority of discoveries was contested between American and Soviet physicists.[59]Their rivalry resulted in a race for new elements and credit for their discoveries, later named theTransfermium Wars.[60]

Reports

edit
Apparatus at Dubna used for the chemical characterization of elements104,105, and106[61]

The first report of thediscovery of element 105came from theJoint Institute for Nuclear Research(JINR) inDubna,Moscow Oblast,Soviet Union,in April 1968. The scientists bombarded243Amwith a beam of22Neions, and reported 9.4 MeV (with a half-life of 0.1–3 seconds) and 9.7 MeV (t1/2> 0.05 s)alpha activitiesfollowed by alpha activities similar to those of either256103 or257103. Based on prior theoretical predictions, the two activity lines were assigned to261105 and260105, respectively.[62]

243
95Am
+22
10Ne
→265−x105 +x
n
(x= 4, 5)

After observing the alpha decays of element 105, the researchers aimed to observespontaneous fission(SF) of the element and study the resulting fission fragments. They published a paper in February 1970, reporting multiple examples of two such activities, with half-lives of 14 ms and2.2±0.5 s.They assigned the former activity to242mfAm[l]and ascribed the latter activity to an isotope of element 105. They suggested that it was unlikely that this activity could come from a transfer reaction instead of element 105, because the yield ratio for this reaction was significantly lower than that of the242mfAm-producing transfer reaction, in accordance with theoretical predictions. To establish that this activity was not from a (22Ne,xn) reaction, the researchers bombarded a243Am target with18O ions; reactions producing256103 and257103 showed very little SF activity (matching the established data), and the reaction producing heavier258103 and259103 produced no SF activity at all, in line with theoretical data. The researchers concluded that the activities observed came from SF of element 105.[62]

In April 1970, a team atLawrence Berkeley Laboratory(LBL), inBerkeley,California,United States, claimed to have synthesized element 105 by bombardingcalifornium-249withnitrogen-15ions, with an alpha activity of 9.1 MeV. To ensure this activity was not from a different reaction, the team attempted other reactions: bombarding249Cf with14N, Pb with15N, and Hg with15N. They stated no such activity was found in those reactions. The characteristics of the daughter nuclei matched those of256103, implying that the parent nuclei were of260105.[62]

249
98Cf
+15
7N
→260105 + 4
n

These results did not confirm the JINR findings regarding the 9.4 MeV or 9.7 MeV alpha decay of260105, leaving only261105 as a possibly produced isotope.[62]

JINR then attempted another experiment to create element 105, published in a report in May 1970. They claimed that they had synthesized more nuclei of element 105 and that the experiment confirmed their previous work. According to the paper, the isotope produced by JINR was probably261105, or possibly260105.[62]This report included an initial chemical examination: the thermal gradient version of the gas-chromatography method was applied to demonstrate that the chloride of what had formed from the SF activity nearly matched that ofniobium pentachloride,rather thanhafnium tetrachloride.The team identified a 2.2-second SF activity in a volatile chloride portraying eka-tantalum properties, and inferred that the source of the SF activity must have been element 105.[62]

In June 1970, JINR made improvements on their first experiment, using a purer target and reducing the intensity of transfer reactions by installing acollimatorbefore the catcher. This time, they were able to find 9.1 MeV alpha activities with daughter isotopes identifiable as either256103 or257103, implying that the original isotope was either260105 or261105.[62]

Naming controversy

edit
Danish nuclear physicistNiels Bohrand German nuclear chemistOtto Hahn,both proposed as possible namesakes for element 105

JINR did not propose a name after their first report claiming synthesis of element 105, which would have been the usual practice. This led LBL to believe that JINR did not have enough experimental data to back their claim.[63]After collecting more data, JINR proposed the namebohrium(Bo) in honor of the Danish nuclear physicistNiels Bohr,a founder of the theories ofatomic structureandquantum theory;[64]they soon changed their proposal tonielsbohrium(Ns) to avoid confusion withboron.[65]Another proposed name wasdubnium.[66][67]When LBL first announced their synthesis of element 105, they proposed that the new element be namedhahnium(Ha) after the German chemistOtto Hahn,the "father of nuclear chemistry", thus creating anelement naming controversy.[68]

In the early 1970s, both teams reported synthesis of the next element, element 106, but did not suggest names.[69]JINR suggested establishing an international committee to clarify the discovery criteria. This proposal was accepted in 1974 and a neutral joint group formed.[70]Neither team showed interest in resolving the conflict through a third party, so the leading scientists of LBL—Albert GhiorsoandGlenn Seaborg—traveled to Dubna in 1975 and met with the leading scientists of JINR—Georgy Flerov,Yuri Oganessian,and others—to try to resolve the conflict internally and render the neutral joint group unnecessary; after two hours of discussions, this failed.[71]The joint neutral group never assembled to assess the claims, and the conflict remained unresolved.[70]In 1979, IUPAC suggestedsystematic element namesto be used as placeholders until permanent names were established; under it, element 105 would beunnilpentium,from the Latin rootsun-andnil-and the Greek rootpent-(meaning "one", "zero", and "five", respectively, the digits of the atomic number). Both teams ignored it as they did not wish to weaken their outstanding claims.[72]

In 1981, theGesellschaft für Schwerionenforschung(GSI;Society for Heavy Ion Research) inDarmstadt,Hesse,West Germany, claimed synthesis of element 107; their report came out five years after the first report from JINR but with greater precision, making a more solid claim on discovery.[62]GSI acknowledged JINR's efforts by suggesting the namenielsbohriumfor the new element.[70]JINR did not suggest a new name for element 105, stating it was more important to determine its discoverers first.[70]

class=notpageimage|
Location ofDubnawithinEuropean Russia

In 1985, theInternational Union of Pure and Applied Chemistry(IUPAC) and theInternational Union of Pure and Applied Physics(IUPAP) formed a Transfermium Working Group (TWG) to assess discoveries and establish final names for the controversial elements.[62]The party held meetings with delegates from the three competing institutes; in 1990, they established criteria on recognition of an element, and in 1991, they finished the work on assessing discoveries and disbanded. These results were published in 1993. According to the report, the first definitely successful experiment was the April 1970 LBL experiment, closely followed by the June 1970 JINR experiment, so credit for the discovery of the element should be shared between the two teams.[62]

LBL said that the input from JINR was overrated in the review. They claimed JINR was only able to unambiguously demonstrate the synthesis of element 105 a year after they did. JINR and GSI endorsed the report.[70]

In 1994, IUPAC published a recommendation on naming the disputed elements. For element 105, they proposedjoliotium(Jl) after the French physicistFrédéric Joliot-Curie,a contributor to the development of nuclear physics and chemistry; this name was originally proposed by the Soviet team for element 102, which by then had long been callednobelium.[73]This recommendation was criticized by the American scientists for several reasons. Firstly, their suggestions were scrambled: the namesrutherfordiumandhahnium,originally suggested by Berkeley for elements 104 and 105, were respectively reassigned to elements 106 and 108. Secondly, elements 104 and 105 were given names favored by JINR, despite earlier recognition of LBL as an equal co-discoverer for both of them. Thirdly and most importantly, IUPAC rejected the nameseaborgiumfor element 106, having just approved a rule that an element could not be named after a living person, even though the 1993 report had given the LBL team the sole credit for its discovery.[74]

In 1995, IUPAC abandoned the controversial rule and established a committee of national representatives aimed at finding a compromise. They suggestedseaborgiumfor element 106 in exchange for the removal of all the other American proposals, except for the established namelawrenciumfor element 103. The equally entrenched namenobeliumfor element 102 was replaced byfleroviumafter Georgy Flerov, following the recognition by the 1993 report that that element had been first synthesized in Dubna. This was rejected by American scientists and the decision was retracted.[75][3]The namefleroviumwas later used for element 114.[76]

In 1996, IUPAC held another meeting, reconsidered all names in hand, and accepted another set of recommendations; it was approved and published in 1997.[77]Element 105 was nameddubnium(Db), afterDubnain Russia, the location of the JINR; the American suggestions were used for elements 102, 103, 104, and 106. The namedubniumhad been used for element 104 in the previous IUPAC recommendation. The American scientists "reluctantly" approved this decision.[78]IUPAC pointed out that the Berkeley laboratory had already been recognized several times, in the naming ofberkelium,californium,andamericium,and that the acceptance of the namesrutherfordiumandseaborgiumfor elements 104 and 106 should be offset by recognizing JINR's contributions to the discovery of elements 104, 105, and 106.[79]

Even after 1997, LBL still sometimes used the namehahniumfor element 105 in their own material, doing so as recently as 2014.[80][81][82][83]However, the problem was resolved in the literature as Jens Volker Kratz, editor ofRadiochimica Acta,refused to accept papers not using the 1997 IUPAC nomenclature.[84]

Isotopes

edit
Main article:Isotopes of dubnium
A chart of nuclide stability as used by JINR in 2012. Characterized isotopes are shown with borders.[85]

Dubnium, having anatomic numberof 105, is asuperheavy element;like all elements with such high atomic numbers, it is very unstable. The longest-lasting known isotope of dubnium,268Db, has a half-life of around a day.[86]No stable isotopes have been seen, and a 2012 calculation by JINR suggested that the half-lives of all dubnium isotopes would not significantly exceed a day.[85][m]Dubnium can only be obtained by artificial production.[n]

The short half-life of dubnium limits experimentation. This is exacerbated by the fact that the most stable isotopes are the hardest to synthesize.[89]Elements with a lower atomic number have stable isotopes with a lowerneutron–proton ratiothan those with higher atomic number, meaning that the target and beam nuclei that could be employed to create the superheavy element have fewer neutrons than needed to form these most stable isotopes. (Different techniques based onrapid neutron captureandtransfer reactionsare being considered as of the 2010s, but those based on the collision of a large and small nucleus still dominate research in the area.)[90][91]

Only a few atoms of268Db can be produced in each experiment, and thus the measured lifetimes vary significantly during the process. As of 2022, following additional experiments performed at the JINR's Superheavy Element Factory (which started operations in 2019), the half-life of268Db is measured to be16+6
−4hours.[13]The second most stable isotope,270Db, has been produced in even smaller quantities: three atoms in total, with lifetimes of 33.4 h,[92]1.3 h, and 1.6 h.[93]These two are the heaviest isotopes of dubnium to date, and both were produced as a result of decay of the heavier nuclei288Mcand294Tsrather than directly, because the experiments that yielded them were originally designed in Dubna for48Cabeams.[94]For its mass,48Ca has by far the greatest neutron excess of all practically stable nuclei, both quantitative and relative,[86]which correspondingly helps synthesize superheavy nuclei with more neutrons, but this gain is compensated by the decreased likelihood of fusion for high atomic numbers.[95]

Predicted properties

edit

According to theperiodic law,dubnium should belong to group 5, withvanadium,niobium,andtantalum.Several studies have investigated the properties of element 105 and found that they generally agreed with the predictions of the periodic law. Significant deviations may nevertheless occur, due torelativistic effects,[o]which dramatically change physical properties on both atomic and macroscopic scales. These properties have remained challenging to measure for several reasons: the difficulties of production of superheavy atoms, the low rates of production, which only allows for microscopic scales, requirements for a radiochemistry laboratory to test the atoms, short half-lives of those atoms, and the presence of many unwanted activities apart from those of synthesis of superheavy atoms. So far, studies have only been performed on single atoms.[3]

Atomic and physical

edit
Relativistic (solid line) and nonrelativistic (dashed line) radial distribution of the 7s valence electrons in dubnium.

A direct relativistic effect is that as the atomic numbers of elements increase, the innermost electrons begin to revolve faster around the nucleus as a result of an increase ofelectromagnetic attractionbetween an electron and a nucleus. Similar effects have been found for the outermost sorbitals(and p1/2ones, though in dubnium they are not occupied): for example, the 7s orbital contracts by 25% in size and is stabilized by 2.6eV.[3]

A more indirect effect is that the contracted s and p1/2orbitalsshieldthe charge of the nucleus more effectively, leaving less for the outer d and f electrons, which therefore move in larger orbitals. Dubnium is greatly affected by this: unlike the previous group 5 members, its 7s electrons are slightly more difficult to extract than its 6d electrons.[3]

Relativistic stabilization of thens orbitals, the destabilization of the(n-1)dorbitals and their spin–orbit splitting for the group 5 elements.

Another effect is thespin–orbit interaction,particularly spin–orbit splitting, which splits the 6d subshell—theazimuthal quantum numberℓ of a d shell is 2—into two subshells, with four of the ten orbitals having their ℓ lowered to 3/2 and six raised to 5/2. All ten energy levels are raised; four of them are lower than the other six. (The three 6d electrons normally occupy the lowest energy levels, 6d3/2.)[3]

A singly ionized atom of dubnium (Db+) should lose a 6d electron compared to a neutral atom; the doubly (Db2+) or triply (Db3+) ionized atoms of dubnium should eliminate 7s electrons, unlike its lighter homologs. Despite the changes, dubnium is still expected to have five valence electrons. As the 6d orbitals of dubnium are more destabilized than the 5d ones of tantalum, and Db3+is expected to have two 6d, rather than 7s, electrons remaining, the resulting +3 oxidation state is expected to be unstable and even rarer than that of tantalum. The ionization potential of dubnium in its maximum +5 oxidation state should be slightly lower than that of tantalum and the ionic radius of dubnium should increase compared to tantalum; this has a significant effect on dubnium's chemistry.[3]

Atoms of dubnium in the solid state should arrange themselves in abody-centered cubicconfiguration, like the previous group 5 elements.[4]The predicted density of dubnium is 21.6 g/cm3.[5]

Chemical

edit
Relativistic (rel) and nonrelativistic (nr) values of the effective charge (QM) and overlap population (OP) in MCl5,where M = V, Nb, Ta, and Db

Computational chemistry is simplest ingas-phase chemistry,in which interactions between molecules may be ignored as negligible. Multiple authors[3]have researched dubnium pentachloride; calculations show it to be consistent with the periodic laws by exhibiting the properties of a compound of a group 5 element. For example, themolecular orbitallevels indicate that dubnium uses three 6d electron levels as expected. Compared to its tantalum analog, dubnium pentachloride is expected to show increasedcovalentcharacter: a decrease in the effective charge on an atom and an increase in the overlap population (between orbitals of dubnium and chlorine).[3]

Calculations ofsolutionchemistry indicate that the maximum oxidation state of dubnium, +5, will be more stable than those of niobium and tantalum and the +3 and +4 states will be less stable. The tendency towardshydrolysisof cations with the highest oxidation state should continue to decrease within group 5 but is still expected to be quite rapid.Complexationof dubnium is expected to follow group 5 trends in its richness. Calculations for hydroxo-chlorido- complexes have shown a reversal in the trends of complex formation and extraction of group 5 elements, with dubnium being more prone to do so than tantalum.[3]

Experimental chemistry

edit

Experimental results of the chemistry of dubnium date back to 1974 and 1976. JINR researchers used athermochromatographicsystem and concluded that the volatility of dubnium bromide was less than that of niobium bromide and about the same as that of hafnium bromide. It is not certain that the detected fission products confirmed that the parent was indeed element 105. These results may imply that dubnium behaves more likehafniumthan niobium.[3]

The next studies on the chemistry of dubnium were conducted in 1988, in Berkeley. They examined whether the most stable oxidation state of dubnium in aqueous solution was +5. Dubnium was fumed twice and washed with concentratednitric acid;sorptionof dubnium on glasscover slipswas then compared with that of the group 5 elements niobium and tantalum and the group 4 elements zirconium and hafnium produced under similar conditions. The group 5 elements are known to sorb on glass surfaces; the group 4 elements do not. Dubnium was confirmed as a group 5 member. Surprisingly, the behavior on extraction from mixed nitric andhydrofluoric acidsolution intomethyl isobutyl ketonediffered between dubnium, tantalum, and niobium. Dubnium did not extract and its behavior resembled niobium more closely than tantalum, indicating that complexing behavior could not be predicted purely from simple extrapolations of trends within a group in the periodic table.[3]

This prompted further exploration of the chemical behavior of complexes of dubnium. Various labs jointly conducted thousands of repetitive chromatographic experiments between 1988 and 1993. All group 5 elements andprotactiniumwere extracted from concentratedhydrochloric acid;after mixing with lower concentrations of hydrogen chloride, small amounts of hydrogen fluoride were added to start selective re-extraction. Dubnium showed behavior different from that of tantalum but similar to that of niobium and its pseudohomolog protactinium at concentrations of hydrogen chloride below 12moles per liter.This similarity to the two elements suggested that the formed complex was eitherDbOX−
4or[Db(OH)
2X
4]−
.After extraction experiments of dubnium fromhydrogen bromideintodiisobutyl carbinol(2,6-dimethylheptan-4-ol), a specific extractant for protactinium, with subsequent elutions with the hydrogen chloride/hydrogen fluoride mix as well as hydrogen chloride, dubnium was found to be less prone to extraction than either protactinium or niobium. This was explained as an increasing tendency to form non‐extractable complexes of multiple negative charges. Further experiments in 1992 confirmed the stability of the +5 state: Db(V) was shown to be extractable from cation‐exchange columns with α‐hydroxyisobutyrate, like the group 5 elements and protactinium; Db(III) and Db(IV) were not. In 1998 and 1999, new predictions suggested that dubnium would extract nearly as well as niobium and better than tantalum from halide solutions, which was later confirmed.[3]

The first isothermal gas chromatography experiments were performed in 1992 with262Db (half-life 35 seconds). The volatilities for niobium and tantalum were similar within error limits, but dubnium appeared to be significantly less volatile. It was postulated that traces of oxygen in the system might have led to formation ofDbOBr
3,which was predicted to be less volatile thanDbBr
5.Later experiments in 1996 showed that group 5 chlorides were more volatile than the corresponding bromides, with the exception of tantalum, presumably due to formation ofTaOCl
3.Later volatility studies of chlorides of dubnium and niobium as a function of controlled partial pressures of oxygen showed that formation of oxychlorides and general volatility are dependent on concentrations of oxygen. The oxychlorides were shown to be less volatile than the chlorides.[3]

In 2004–05, researchers from Dubna and Livermore identified a new dubnium isotope,268Db, as a fivefold alpha decay product of the newly createdelement 115.This new isotope proved to be long-lived enough to allow further chemical experimentation, with a half-life of over a day. In the 2004 experiment, a thin layer with dubnium was removed from the surface of the target and dissolved inaqua regiawith tracers and alanthanumcarrier, from which various +3, +4, and +5 species were precipitated on addingammonium hydroxide.The precipitate was washed and dissolved in hydrochloric acid, where it converted to nitrate form and was then dried on a film and counted. Mostly containing a +5 species, which was immediately assigned to dubnium, it also had a +4 species; based on that result, the team decided that additional chemical separation was needed. In 2005, the experiment was repeated, with the final product being hydroxide rather than nitrate precipitate, which was processed further in both Livermore (based on reverse phase chromatography) and Dubna (based on anion exchange chromatography). The +5 species was effectively isolated; dubnium appeared three times in tantalum-only fractions and never in niobium-only fractions. It was noted that these experiments were insufficient to draw conclusions about the general chemical profile of dubnium.[96]

In 2009, at the JAEA tandem accelerator in Japan, dubnium was processed in nitric and hydrofluoric acid solution, at concentrations where niobium formsNbOF−
4and tantalum formsTaF−
6.Dubnium's behavior was close to that of niobium but not tantalum; it was thus deduced that dubnium formedDbOF−
4.From the available information, it was concluded that dubnium often behaved like niobium, sometimes like protactinium, but rarely like tantalum.[97]

In 2021, the volatile heavy group 5 oxychlorides MOCl3(M = Nb, Ta, Db) were experimentally studied at the JAEA tandem accelerator. The trend in volatilities was found to be NbOCl3> TaOCl3≥ DbOCl3,so that dubnium behaves in line with periodic trends.[98]

Notes

edit
  1. ^Innuclear physics,an element is calledheavyif 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 than103(although there are other definitions, such as atomic number greater than100[15]or112;[16]sometimes, the term is presented an equivalent to the term "transactinide", which puts an upper limit before the beginning of the hypotheticalsuperactinideseries).[17]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 the JINR led by Oganessian published results of their attempt to create hassium in a symmetric136Xe +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 2.5pb.[18]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.[19]
  3. ^The amount of energy applied to the beam particle to accelerate it can also influence the value of cross section. For example, in the28
    14    Si
    +1
    0    n
    →28
    13    Al
    +1
    1    p
    reaction, cross section changes smoothly from 370 mb at 12.3 MeV to 160 mb at 18.3 MeV, with a broad peak at 13.5 MeV with the maximum value of 380 mb.[23]
  4. ^This figure also marks the generally accepted upper limit for lifetime of a compound nucleus.[28]
  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.[30]Such separation can also be aided by atime-of-flight measurementand a recoil energy measurement; a combination of the two may allow to estimate the mass of a nucleus.[31]
  6. ^Not all decay modes are caused by electrostatic repulsion. For example,beta decayis caused by theweak interaction.[38]
  7. ^It was already known by the 1960s that ground states of nuclei differed in energy and shape as well as that certain magic numbers of nucleons corresponded to greater stability of a nucleus. However, it was assumed that there was no nuclear structure in superheavy nuclei as they were too deformed to form one.[43]
  8. ^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 superheavy nuclei.[48]The first direct measurement of mass of a superheavy nucleus was reported in 2018 at LBNL.[49]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).[50]
  9. ^If the decay occurred in a vacuum, then since total momentum of an isolated system before and after the decaymust be preserved,the daughter nucleus would also receive a small velocity. The ratio of the two velocities, and accordingly the ratio of the kinetic energies, would thus be inverse to the ratio of the two masses. The decay energy equals the sum of the known kinetic energy of the alpha particle and that of the daughter nucleus (an exact fraction of the former).[39]The calculations hold for an experiment as well, but the difference is that the nucleus does not move after the decay because it is tied to the detector.
  10. ^Spontaneous fission was discovered by Soviet physicistGeorgy Flerov,[51]a leading scientist at JINR, and thus it was a "hobbyhorse" for the facility.[52]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.[28]They thus preferred to link new isotopes to the already known ones by successive alpha decays.[51]
  11. ^For instance, element 102 was mistakenly identified in 1957 at the Nobel Institute of Physics inStockholm,Stockholm County,Sweden.[53]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.[54]The following year, RL was unable to reproduce the Swedish results and announced instead their synthesis of the element; that claim was also disproved later.[54]JINR insisted that they were the first to create the element and suggested a name of their own for the new element,joliotium;[55]the Soviet name was also not accepted (JINR later referred to the naming of the element 102 as "hasty" ).[56]This name was proposed to IUPAC in a written response to their ruling on priority of discovery claims of elements, signed 29 September 1992.[56]The name "nobelium" remained unchanged on account of its widespread usage.[57]
  12. ^This notation signifies that the nucleus is anuclear isomerthat decays via spontaneous fission.
  13. ^The current experimental value is 16+6
    −4    hours for268Db, but the statisticallaw of large numbers,on which the determination of half-lives relies, cannot be directly applied due to a very limited number of experiments (decays). The range of uncertainty is an indication that the half-life period lies within this range with 95% probability.
  14. ^The modern theory of the atomic nucleus does not suggest a long-lived isotope of dubnium, but claims were made in the past that unknown isotopes of superheavy elements existed primordially on the Earth: for example, such a claim was raised for267108 of a half-life of 400 to 500 million years in 1963[87]or292122 of a half-life of over 100 million years in 2009;[88]neither claim gained acceptance.
  15. ^Relativistic effects arise when an object moves at velocities comparable to the speed of light; in heavy atoms, the quickly moving objects are electrons.

References

edit
  1. ^"dubnium".Merriam-Webster.com Dictionary.Merriam-Webster.RetrievedMarch 24,2018.
  2. ^"dubnium".LexicoUK English Dictionary.Oxford University Press.Archived fromthe originalon December 18, 2019.
  3. ^abcdefghijklmnopqHoffman, D. C.; Lee, D. M.; Pershina, V. (2006). "Transactinides and the future elements". In Morss, L.R.; Edelstein, N. M.; Fuger, Jean (eds.).The Chemistry of the Actinide and Transactinide Elements(3rd ed.).Springer Science+Business Media.pp. 1652–1752.ISBN978-1-4020-3555-5.
  4. ^abcÖstlin, A.; Vitos, L. (2011). "First-principles calculation of the structural stability of 6d transition metals".Physical Review B.84(11).Bibcode:2011PhRvB..84k3104O.doi:10.1103/PhysRevB.84.113104.
  5. ^abGyanchandani, Jyoti; Sikka, S. K. (May 10, 2011). "Physical properties of the 6 d -series elements from density functional theory: Close similarity to lighter transition metals".Physical Review B.83(17): 172101.doi:10.1103/PhysRevB.83.172101.
  6. ^Kratz; Lieser (2013).Nuclear and Radiochemistry: Fundamentals and Applications(3rd ed.). p. 631.
  7. ^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.ISBN978-3-540-07109-9.RetrievedOctober 4,2013.
  8. ^"Dubnium".Royal Chemical Society.RetrievedOctober 9,2017.
  9. ^Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021)."The NUBASE2020 evaluation of nuclear properties"(PDF).Chinese Physics C.45(3): 030001.doi:10.1088/1674-1137/abddae.
  10. ^Münzenberg, G.; Gupta, M. (2011). "Production and Identification of Transactinide Elements".Handbook of Nuclear Chemistry.Springer. p. 877.doi:10.1007/978-1-4419-0720-2_19.
  11. ^abSix New Isotopes of the Superheavy Elements Discovered.Berkeley Lab. News center. October 26, 2010
  12. ^abOganessian, Yu. Ts.; Utyonkov, V. K.; Kovrizhnykh, N. D.; et al. (2022). "New isotope286Mc produced in the243Am+48Ca reaction ".Physical Review C.106(064306).doi:10.1103/PhysRevC.106.064306.
  13. ^abcOganessian, Yu. Ts.; Utyonkov, V. K.; Kovrizhnykh, N. D.; et al. (September 29, 2022)."First experiment at the Super Heavy Element Factory: High cross section of288Mc in the243Am+48Ca reaction and identification of the new isotope264Lr ".Physical Review C.106(3): L031301.doi:10.1103/PhysRevC.106.L031301.S2CID252628992.
  14. ^Khuyagbaatar, J.; Yakushev, A.; Düllmann, Ch. E.; et al. (2014)."48Ca+249Bk Fusion Reaction Leading to Element Z=117: Long-Lived α-Decaying270Db and Discovery of266Lr ".Physical Review Letters.112(17): 172501.Bibcode:2014PhRvL.112q2501K.doi:10.1103/PhysRevLett.112.172501.hdl:1885/148814.PMID24836239.S2CID5949620.
  15. ^Krämer, K. (2016)."Explainer: superheavy elements".Chemistry World.RetrievedMarch 15,2020.
  16. ^"Discovery of Elements 113 and 115".Lawrence Livermore National Laboratory.Archived fromthe originalon September 11, 2015.RetrievedMarch 15,2020.
  17. ^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.ISBN978-1-119-95143-8.S2CID127060181.
  18. ^Oganessian, Yu. Ts.;Dmitriev, S. N.; Yeremin, A. V.; et al. (2009). "Attempt to produce the isotopes of element 108 in the fusion reaction136Xe +136Xe ".Physical Review C.79(2): 024608.doi:10.1103/PhysRevC.79.024608.ISSN0556-2813.
  19. ^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.S2CID123288075.Archived fromthe original(PDF)on June 7, 2015.RetrievedOctober 20,2012.
  20. ^Subramanian, S.(August 28, 2019)."Making New Elements Doesn't Pay. Just Ask This Berkeley Scientist".Bloomberg Businessweek.RetrievedJanuary 18,2020.
  21. ^abcdefIvanov, D. (2019)."Сверхтяжелые шаги в неизвестное"[Superheavy steps into the unknown].nplus1.ru(in Russian).RetrievedFebruary 2,2020.
  22. ^Hinde, D. (2017)."Something new and superheavy at the periodic table".The Conversation.RetrievedJanuary 30,2020.
  23. ^Kern, B. D.; Thompson, W. E.; Ferguson, J. M. (1959). "Cross sections for some (n, p) and (n, α) reactions".Nuclear Physics.10:226–234.Bibcode:1959NucPh..10..226K.doi:10.1016/0029-5582(59)90211-1.
  24. ^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.hdl:1885/148847.ISSN2100-014X.
  25. ^"Nuclear Reactions"(PDF).pp. 7–8.RetrievedJanuary 27,2020.Published asLoveland, W. D.; Morrissey, D. J.;Seaborg, G. T.(2005). "Nuclear Reactions".Modern Nuclear Chemistry.John Wiley & Sons, Inc.pp. 249–297.doi:10.1002/0471768626.ch10.ISBN978-0-471-76862-3.
  26. ^abKrása, A. (2010). "Neutron Sources for ADS".Faculty of Nuclear Sciences and Physical Engineering.Czech Technical University in Prague:4–8.S2CID28796927.
  27. ^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.ISSN1365-3075.S2CID95737691.
  28. ^abHyde, 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.ISSN2193-3405.S2CID99193729.
  29. ^abcdChemistry World(2016)."How to Make Superheavy Elements and Finish the Periodic Table [Video]".Scientific American.RetrievedJanuary 27,2020.
  30. ^Hoffman, Ghiorso & Seaborg 2000,p. 334.
  31. ^Hoffman, Ghiorso & Seaborg 2000,p. 335.
  32. ^Zagrebaev, Karpov & Greiner 2013,p. 3.
  33. ^Beiser 2003,p. 432.
  34. ^abPauli, N. (2019)."Alpha decay"(PDF).Introductory Nuclear, Atomic and Molecular Physics (Nuclear Physics Part).Université libre de Bruxelles.RetrievedFebruary 16,2020.
  35. ^abcdePauli, N. (2019)."Nuclear fission"(PDF).Introductory Nuclear, Atomic and Molecular Physics (Nuclear Physics Part).Université libre de Bruxelles.RetrievedFebruary 16,2020.
  36. ^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.ISSN0556-2813.
  37. ^Audi et al. 2017,pp. 030001-129–030001-138.
  38. ^Beiser 2003,p. 439.
  39. ^abBeiser 2003,p. 433.
  40. ^Audi et al. 2017,p. 030001-125.
  41. ^Aksenov, N. V.; Steinegger, P.; Abdullin, F. Sh.; et al. (2017). "On the volatility of nihonium (Nh, Z = 113)".The European Physical Journal A.53(7): 158.Bibcode:2017EPJA...53..158A.doi:10.1140/epja/i2017-12348-8.ISSN1434-6001.S2CID125849923.
  42. ^Beiser 2003,p. 432–433.
  43. ^abcOganessian, Yu. (2012)."Nuclei in the" Island of Stability "of Superheavy Elements".Journal of Physics: Conference Series.337(1): 012005-1–012005-6.Bibcode:2012JPhCS.337a2005O.doi:10.1088/1742-6596/337/1/012005.ISSN1742-6596.
  44. ^Moller, P.; Nix, J. R. (1994).Fission properties of the heaviest elements(PDF).Dai 2 Kai Hadoron Tataikei no Simulation Symposium, Tokai-mura, Ibaraki, Japan.University of North Texas.RetrievedFebruary 16,2020.
  45. ^abOganessian, Yu. Ts. (2004)."Superheavy elements".Physics World.17(7): 25–29.doi:10.1088/2058-7058/17/7/31.RetrievedFebruary 16,2020.
  46. ^Schädel, M. (2015)."Chemistry of the superheavy elements".Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.373(2037): 20140191.Bibcode:2015RSPTA.37340191S.doi:10.1098/rsta.2014.0191.ISSN1364-503X.PMID25666065.
  47. ^Hulet, E. K. (1989).Biomodal spontaneous fission.50th Anniversary of Nuclear Fission, Leningrad, USSR.Bibcode:1989nufi.rept...16H.
  48. ^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.ISSN0031-9228.OSTI1337838.S2CID119531411.
  49. ^Grant, A. (2018). "Weighing the heaviest elements".Physics Today.doi:10.1063/PT.6.1.20181113a.S2CID239775403.
  50. ^Howes, L. (2019)."Exploring the superheavy elements at the end of the periodic table".Chemical & Engineering News.RetrievedJanuary 27,2020.
  51. ^abRobinson, A. E. (2019)."The Transfermium Wars: Scientific Brawling and Name-Calling during the Cold War".Distillations.RetrievedFebruary 22,2020.
  52. ^"Популярная библиотека химических элементов. Сиборгий (экавольфрам)"[Popular library of chemical elements. Seaborgium (eka-tungsten)].n-t.ru(in Russian).RetrievedJanuary 7,2020.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.
  53. ^"Nobelium - Element information, properties and uses | Periodic Table".Royal Society of Chemistry.RetrievedMarch 1,2020.
  54. ^abKragh 2018,pp. 38–39.
  55. ^Kragh 2018,p. 40.
  56. ^abGhiorso, 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.S2CID95069384.Archived(PDF)from the original on November 25, 2013.RetrievedSeptember 7,2016.
  57. ^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.
  58. ^Choppin, G. R.; Liljenzin, J.-O.; Rydberg, J. (2002).Radiochemistry and Nuclear Chemistry.Elsevier.p. 416.ISBN978-0-7506-7463-8.
  59. ^Hoffman, D. C. (1996).The Transuranium Elements: From Neptunium and Plutonium to Element 112(PDF)(Report). Lawrence Livermore National Laboratory.Archived(PDF)from the original on October 9, 2017.RetrievedOctober 10,2017.
  60. ^Karol, P. (1994)."The Transfermium Wars".Chemical & Engineering News.74(22): 2–3.doi:10.1021/cen-v072n044.p002.
  61. ^Zvara, I. J. (2003)."Dubnium".Chemical and Engineering News.81(36): 182.doi:10.1021/cen-v081n036.p182.Archivedfrom the original on December 31, 2017.RetrievedOctober 9,2017.
  62. ^abcdefghijBarber, R. C.;Greenwood, N. N.;Hrynkiewicz, A. Z.; et al. (1993)."Discovery of the Transfermium elements"(PDF).Pure and Applied Chemistry.65(8): 1757.doi:10.1351/pac199365081757.S2CID195819585.Archived(PDF)from the original on September 20, 2016.RetrievedSeptember 7,2016.
  63. ^"Dubnium | chemical element".Encyclopedia Britannica.Archivedfrom the original on March 25, 2018.RetrievedMarch 25,2018.
  64. ^Städtler, Ingrid; Niemann, Hans (1971).Symbolik und Fachausdruecke. Mathematik, Physik, Chemie(in German). Germany: Verlag Enzyklopädie. p. 83.
  65. ^Industries atomiques et spatiales, Volume 16(in French). Switzerland. 1972. pp. 30–31.Archivedfrom the original on December 23, 2022.RetrievedSeptember 8,2022.{{cite book}}:CS1 maint: location missing publisher (link)
  66. ^Radiochemistry.Royal Society of Chemistry. 1972.ISBN9780851862545.
  67. ^Suomen kemistilehti.Suomalaisten Kemistien Seura. 1971.
  68. ^Fontani, M.; Costa, M.; Orna, M. V. (2014).The Lost Elements: The Periodic Table's Shadow Side.Oxford University Press. p. 386.ISBN978-0-19-938335-1.Archivedfrom the original on February 27, 2018.
  69. ^Hoffmann, K. (1987).Можно ли сделать золото? Мошенники, обманщики и ученые в истории химических элементов[Can one make gold? Swindlers, deceivers and scientists from the history of the chemical elements] (in Russian). Nauka. pp. 180–181.Translation fromHoffmann, K. (1979).Kann man Gold machen? Gauner, Gaukler und Gelehrte. Aus der Geschichte der chemischen Elemente[Can one make gold? Swindlers, deceivers and scientists. From the history of the chemical elements] (in German). Urania.
  70. ^abcdeGhiorso, 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.S2CID95069384.Archived(PDF)from the original on November 25, 2013.RetrievedSeptember 7,2016.
  71. ^Robinson, A. (2017)."An Attempt to Solve the Controversies Over Elements 104 and 105: A Meeting in Russia, 23 September 1975".Bulletin of the American Physical Society.62(1): B10.003.Bibcode:2017APS..APRB10003R.Archivedfrom the original on September 22, 2017.RetrievedOctober 14,2017.
  72. ^Öhrström, L.; Holden, N. E. (2016)."The Three-letter Element Symbols".Chemistry International.38(2).doi:10.1515/ci-2016-0204.
  73. ^"Names and symbols of transfermium elements (IUPAC Recommendations 1994)"(PDF).Pure and Applied Chemistry.66(12): 2419–2421. 1994.doi:10.1351/pac199466122419.Archived(PDF)from the original on September 22, 2017.RetrievedSeptember 7,2016.
  74. ^Yarris, L. (1994)."Naming of element 106 disputed by international committee".Archivedfrom the original on July 1, 2016.RetrievedSeptember 7,2016.
  75. ^Hoffman, Ghiorso & Seaborg 2000,pp. 389–394
  76. ^Loss, R. D.; Corish, J. (2012)."Names and symbols of the elements with atomic numbers 114 and 116 (IUPAC Recommendations 2012)"(PDF).Pure and Applied Chemistry.84(7): 1669–1672.doi:10.1351/PAC-REC-11-12-03.S2CID96830750.Archived(PDF)from the original on August 3, 2017.RetrievedApril 21,2018.
  77. ^Bera, J. K. (1999). "Names of the Heavier Elements".Resonance.4(3): 53–61.doi:10.1007/BF02838724.S2CID121862853.
  78. ^Hoffman, Ghiorso & Seaborg 2000,pp. 369–399
  79. ^"Names and symbols of transfermium elements (IUPAC Recommendations 1997)".Pure and Applied Chemistry.69(12): 2471–2474. 1997.doi:10.1351/pac199769122471.
  80. ^"Periodic Table of the Elements".lbl.gov.Lawrence Berkeley National Laboratory. 1999.Archivedfrom the original on April 21, 2021.RetrievedDecember 6,2022.
  81. ^Wilk, P. A. (2001).Properties of Group Five and Group Seven transactinium elements(PhD). University of California, Berkeley.doi:10.2172/785268.OSTI785268.Archivedfrom the original on October 31, 2022.RetrievedDecember 6,2022.
  82. ^Buhler, Brendan (2014)."Branding the Elements: Berkeley Stakes its Claims on the Periodic Table".alumni.berkeley.edu.Cal Alumni Association.Archivedfrom the original on October 31, 2022.RetrievedDecember 6,2022.Poor element 105 has had five different names—Berkeley partisans still call it hahnium.
  83. ^@BerkeleyLab (January 8, 2014)."#16elements from Berkeley Lab: mendelevium, nobelium, lawrencium, rutherfordium, hahnium, seaborgium"(Tweet) – viaTwitter.
  84. ^Armbruster, Peter; Münzenberg, Gottfried (2012)."An experimental paradigm opening the world of superheavy elements".The European Physical Journal H.37(2): 237–309.Bibcode:2012EPJH...37..237A.doi:10.1140/epjh/e2012-20046-7.S2CID123446987.Archivedfrom the original on December 6, 2022.RetrievedDecember 6,2022.
  85. ^abKarpov, A. V.; Zagrebaev, V. I.; Palenzuela, Y. M.; Greiner, W. (2013). "Superheavy Nuclei: Decay and Stability". In Greiner, W. (ed.).Exciting Interdisciplinary Physics.FIAS Interdisciplinary Science Series. Springer International Publishing. pp. 69–79.doi:10.1007/978-3-319-00047-3_6.ISBN978-3-319-00046-6.
  86. ^abAudi, G.; Kondev, F. G.; Wang, M.; et al. (2012)."The NUBASE2012 evaluation of nuclear properties"(PDF).Chinese Physics C.36(12): 1157–1286.Bibcode:2012ChPhC..36....1A.doi:10.1088/1674-1137/36/12/001.S2CID123457161.Archived fromthe original(PDF)on July 6, 2016.
  87. ^Emsley, J. (2011).Nature's Building Blocks: An A-Z Guide to the Elements(New ed.). New York: Oxford University Press. pp. 215–217.ISBN978-0-19-960563-7.
  88. ^Marinov, A.; Rodushkin, I.; Kolb, D.; et al. (2010). "Evidence for a long-lived superheavy nucleus with atomic mass number A=292 and atomic number Z=~122 in natural Th".International Journal of Modern Physics E.19(1): 131–140.arXiv:0804.3869.Bibcode:2010IJMPE..19..131M.doi:10.1142/S0218301310014662.S2CID117956340.
  89. ^Karpov, A. V.; Zagrebaev, V. I.; Palenzuela, Y. M.; et al. (2013). "Superheavy Nuclei: Decay and Stability".Exciting Interdisciplinary Physics.FIAS Interdisciplinary Science Series. p. 69.doi:10.1007/978-3-319-00047-3_6.ISBN978-3-319-00046-6.
  90. ^Botvina, Al.; Mishustin, I.; Zagrebaev, V.; et al. (2010). "Possibility of synthesizing superheavy elements in nuclear explosions".International Journal of Modern Physics E.19(10): 2063–2075.arXiv:1006.4738.Bibcode:2010IJMPE..19.2063B.doi:10.1142/S0218301310016521.S2CID55807186.
  91. ^Wuenschel, S.; Hagel, K.; Barbui, M.; et al. (2018). "An experimental survey of the production of alpha decaying heavy elements in the reactions of238U +232Th at 7.5-6.1 MeV/nucleon ".Physical Review C.97(6): 064602.arXiv:1802.03091.Bibcode:2018PhRvC..97f4602W.doi:10.1103/PhysRevC.97.064602.S2CID67767157.
  92. ^Oganessian, Yu. Ts.; Abdullin, F. Sh.; Bailey, P. D.; et al. (2010)."Synthesis of a New Element with Atomic Number Z=117".Physical Review Letters.104(14): 142502.Bibcode:2010PhRvL.104n2502O.doi:10.1103/PhysRevLett.104.142502.PMID20481935.Archivedfrom the original on December 19, 2016.
  93. ^Khuyagbaatar, J.; Yakushev, A.; Düllmann, Ch. E.; et al. (2014)."48Ca +249Bk Fusion Reaction Leading to ElementZ= 117: Long-Lived α-Decaying270Db and Discovery of266Lr "(PDF).Physical Review Letters.112(17): 172501.Bibcode:2014PhRvL.112q2501K.doi:10.1103/PhysRevLett.112.172501.hdl:1885/148814.PMID24836239.S2CID5949620.Archived(PDF)from the original on August 17, 2017.
  94. ^Wills, S.; Berger, L. (2011)."Science Magazine Podcast. Transcript, 9 September 2011"(PDF).Science.Archived(PDF)from the original on October 18, 2016.RetrievedOctober 12,2016.
  95. ^Oganessian, Yu. Ts.; Sobiczewski, A.; Ter-Akopian, G. M. (2017). "Superheavy nuclei: from prediction to discovery".Physica Scripta.92(2): 023003.Bibcode:2017PhyS...92b3003O.doi:10.1088/1402-4896/aa53c1.S2CID125713877.
  96. ^Stoyer, N. J.; Landrum, J. H.; Wilk, P. A.; et al. (2006).Chemical Identification of a Long-Lived Isotope of Dubnium, a Descendant of Element 115(PDF)(Report). IX International Conference on Nucleus Nucleus Collisions.Archived(PDF)from the original on January 31, 2017.RetrievedOctober 9,2017.
  97. ^Nagame, Y.; Kratz, J. V.; Schädel, M. (2016)."Chemical properties of rutherfordium (Rf) and dubnium (Db) in the aqueous phase"(PDF).EPJ Web of Conferences.131:07007.Bibcode:2016EPJWC.13107007N.doi:10.1051/epjconf/201613107007.Archived(PDF)from the original on April 28, 2019.
  98. ^Chiera, Nadine M.; Sato, Tetsuya K.; Eichler, Robert; et al. (2021)."Chemical Characterization of a Volatile Dubnium Compound, DbOCl3".Angewandte Chemie International Edition.60(33): 17871–17874.doi:10.1002/anie.202102808.PMC8456785.PMID33978998.

Bibliography

edit
Wikimedia Commons has media related toDubnium.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Dubnium&oldid=1231693487"