Hubbry Logo
RoentgeniumRoentgeniumMain
Open search
Roentgenium
Community hub
Roentgenium
logo
7 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Contribute something
Roentgenium
Roentgenium
Roentgenium
View on Wikipedia
from Wikipedia

Roentgenium, 111Rg
Roentgenium
Pronunciation
Mass number[282] (unconfirmed: 286)
Roentgenium 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
Au
↑
Rg
↓
—
darmstadtium ← roentgenium → copernicium
Atomic number (Z)111
Groupgroup 11
Periodperiod 7
Block  d-block
Electron configuration[Rn] 5f14 6d9 7s2 (predicted)[1][2]
Electrons per shell2, 8, 18, 32, 32, 17, 2 (predicted)
Physical properties
Phase at STPsolid (predicted)[3]
Density (near r.t.)22–24 g/cm3 (predicted)[4][5]
Atomic properties
Oxidation statescommon: (none)
(−1), (+3), (+5)[2]
Ionization energies
  • 1st: 1020 kJ/mol
  • 2nd: 2070 kJ/mol
  • 3rd: 3080 kJ/mol
  • (more) (all estimated)[2]
Atomic radiusempirical: 114 pm (predicted)[6]
Covalent radius121 pm (estimated)[7]
Other properties
Natural occurrencesynthetic
Crystal structure ​body-centered cubic (bcc)
Body-centered cubic crystal structure for roentgenium

(predicted)[3]
CAS Number54386-24-2
History
Namingafter Wilhelm Röntgen
DiscoveryGesellschaft für Schwerionenforschung (1994)
Isotopes of roentgenium
Main isotopes[8] Decay
Isotope abun­dance half-life (t1/2) mode pro­duct
279Rg synth 0.09 s[9] α87% 275Mt
SF13% –
280Rg synth 3.9 s α 276Mt
281Rg synth 11 s[10] SF86% –
α14% 277Mt
282Rg synth 100 s α 278Mt
283Rg synth 5.1 min?[11] SF –
286Rg synth 10.7 min?[11] α 282Mt
 Category: Roentgenium
| references

Roentgenium (German: [ʁœntˈɡeːni̯ʊm] ⓘ) is a synthetic chemical element; it has symbol Rg and atomic number 111. It is extremely radioactive and can only be created in a laboratory. The most stable known isotope, roentgenium-282, has a half-life of 130 seconds, although the unconfirmed roentgenium-286 may have a longer half-life of about 10.7 minutes. Roentgenium was first created in December 1994 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany. It is named after the physicist Wilhelm Röntgen (also spelled Roentgen), who discovered X-rays. Only a few roentgenium atoms have ever been synthesized, and they have no practical application.

In the periodic table, it is a d-block transactinide element. It is a member of the 7th period and is placed in the group 11 elements, although no chemical experiments have been carried out to confirm that it behaves as the heavier homologue to gold in group 11 as the ninth member of the 6d series of transition metals. Roentgenium is calculated to have similar properties to its lighter homologues, copper, silver, and gold, although it may show some differences from them.

Introduction

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

Synthesis of superheavy nuclei

[edit]
A graphic depiction of a nuclear fusion reaction
A graphic depiction of a nuclear fusion reaction. Two nuclei fuse into one, emitting a neutron. 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 nucleus is 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 of mass, the greater the possibility that the two react.[17] 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 only fuse into one 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.[18] The energy applied to the beam nuclei to accelerate them can cause them to reach speeds as high as one-tenth of the speed of light. However, if too much energy is applied, the beam nucleus can fall apart.[18]

Coming close enough alone is not enough for two nuclei to fuse: when two nuclei approach each other, they usually remain together for about 10−20 seconds and then part ways (not necessarily in the same composition as before the reaction) rather than form a single nucleus.[18][19] This happens because during the attempted formation of a single nucleus, electrostatic repulsion tears apart the nucleus that is being formed.[18] Each pair of a target and a beam is characterized by its cross 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 can tunnel through electrostatic repulsion. If the two nuclei can stay close past that phase, multiple nuclear interactions result in redistribution of energy and an energy equilibrium.[18]

External videos
video icon Visualization of unsuccessful nuclear fusion, based on calculations from the Australian National University[21]

The resulting merger is an excited state[22]—termed a compound nucleus—and thus it is very unstable.[18] To reach a more stable state, the temporary merger may fission without formation of a more stable nucleus.[23] Alternatively, the compound nucleus may eject a few neutrons, which would carry away the excitation energy; if the latter is not sufficient for a neutron expulsion, the merger would produce a gamma ray. This happens in about 10−16 seconds after the initial nuclear collision and results in creation of a more stable nucleus.[23] The definition by the IUPAC/IUPAP Joint Working Party (JWP) 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 electrons and thus display its chemical properties.[24][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.[26] 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 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.[26] The transfer takes about 10−6 seconds; in order to be detected, the nucleus must survive this long.[29] The nucleus is recorded again once its decay is registered, and the location, the energy, and the time of the decay are measured.[26]

Stability of a nucleus is provided by the strong interaction. However, its range is very short; as nuclei become larger, its influence on the outermost nucleons (protons and neutrons) weakens. At the same time, the nucleus is torn apart by electrostatic repulsion between protons, and its range is not limited.[30] Total binding energy provided 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.[31][32] Superheavy nuclei are thus theoretically predicted[33] and have so far been observed[34] to predominantly decay via decay modes that are caused by such repulsion: alpha decay and spontaneous fission.[f] Almost all alpha emitters have over 210 nucleons,[36] and the lightest nuclide primarily undergoing spontaneous fission has 238.[37] In both decay modes, nuclei are inhibited from decaying by corresponding energy barriers for each mode, but they can be tunneled through.[31][32]

Apparatus for creation of superheavy elements
Scheme of an apparatus for creation of superheavy elements, based on the Dubna Gas-Filled Recoil Separator set up in the Flerov Laboratory of Nuclear Reactions in JINR. The trajectory within the detector and the beam focusing apparatus changes because of a dipole magnet in the former and quadrupole magnets in the latter.[38]

Alpha particles are commonly produced in radioactive decays because the 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.[39] Spontaneous fission is caused by electrostatic repulsion tearing the nucleus apart and produces various nuclei in different instances of identical nuclei fissioning.[32] As the atomic number increases, spontaneous fission rapidly becomes more important: spontaneous fission partial half-lives decrease by 23 orders of magnitude from uranium (element 92) to nobelium (element 102),[40] and by 30 orders of magnitude from thorium (element 90) to fermium (element 100).[41] The earlier liquid drop model thus suggested that spontaneous fission would occur nearly instantly due to disappearance of the fission barrier for nuclei with about 280 nucleons.[32][42] The later nuclear shell model suggested that nuclei with about 300 nucleons would form an island of stability in which nuclei will be more resistant to spontaneous fission and will primarily undergo alpha decay with longer half-lives.[32][42] 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.[43] Experiments on lighter superheavy nuclei,[44] as well as those closer to the expected island,[40] 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.)[26] The known nucleus can be recognized by the specific characteristics of decay it undergoes such as decay energy (or more specifically, the kinetic energy of 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]

History

[edit]
Roentgenium was named after the physicist Wilhelm Röntgen, the discoverer of X-rays.

Official discovery

[edit]

Roentgenium was first synthesized by an international team led by Sigurd Hofmann at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany, on December 8, 1994.[55] The team bombarded a target of bismuth-209 with accelerated nuclei of nickel-64 and detected three nuclei of the isotope 272111:

209
83Bi + 64
28Ni → 272111 + 1
0n

This reaction had previously been conducted at the Joint Institute for Nuclear Research in Dubna (then in the Soviet Union) in 1986, but no atoms of 272111 had then been observed.[56] In 2001, the IUPAC/IUPAP Joint Working Party (JWP) concluded that there was insufficient evidence for the discovery at that time.[57] The GSI team repeated their experiment in 2002 and detected three more atoms.[58][59] In their 2003 report, the JWP decided that the GSI team should be acknowledged for the discovery of this element.[60]

Backdrop for presentation of the discovery and recognition of roentgenium at GSI Darmstadt

Naming

[edit]

Using Mendeleev's nomenclature for unnamed and undiscovered elements, roentgenium should be known as eka-gold. In 1979, IUPAC published recommendations according to which the element was to be called unununium (with the corresponding symbol of Uuu),[61] a systematic element name as a placeholder, until the element was discovered (and the discovery then confirmed) and a permanent name was decided on. Although widely used in the chemical community on all levels, from chemistry classrooms to advanced textbooks, the recommendations were mostly ignored among scientists in the field, who called it element 111, with the symbol of E111, (111) or even simply 111.[2]

The name roentgenium (Rg) was suggested by the GSI team[62] in 2004, to honor the German physicist Wilhelm Conrad Röntgen, the discoverer of X-rays.[62] This name was accepted by IUPAC on November 1, 2004.[62]

Isotopes

[edit]
Main article: Isotopes of roentgenium
List of roentgenium isotopes
Isotope Half-life[l] Decay
mode 		Discovery
year 		Discovery
reaction
Value ref
272Rg 4.2 ms [8] α 1994 209Bi(64Ni,n)
274Rg 20 ms [8] α 2004 278Nh(—,α)
278Rg 4.6 ms [63] α 2006 282Nh(—,α)
279Rg 90 ms [63] α, SF 2003 287Mc(—,2α)
280Rg 3.9 s [63] α, EC 2003 288Mc(—,2α)
281Rg 11 s [63] SF, α 2010 293Ts(—,3α)
282Rg 130 s [8] α 2010 294Ts(—,3α)
283Rg[m] 5.1 min [11] SF 1999 283Cn(e−,νe)
286Rg[m] 10.7 min [11] α 1998 290Fl(e−,νeα)

Roentgenium has no stable or naturally occurring isotopes. Several radioactive isotopes have been synthesized in the laboratory, either by fusion of the nuclei of lighter elements or as intermediate decay products of heavier elements. Nine different isotopes of roentgenium have been reported with atomic masses 272, 274, 278–283, and 286 (283 and 286 unconfirmed), two of which, roentgenium-272 and roentgenium-274, have known but unconfirmed metastable states. All of these decay through alpha decay or spontaneous fission,[64] though 280Rg may also have an electron capture branch.[65]

Stability and half-lives

[edit]

All roentgenium isotopes are extremely unstable and radioactive; in general, the heavier isotopes are more stable than the lighter. The most stable known roentgenium isotope, 282Rg, is also the heaviest known roentgenium isotope; it has a half-life of 100 seconds. The unconfirmed 286Rg is even heavier and appears to have an even longer half-life of about 10.7 minutes, which would make it one of the longest-lived superheavy nuclides known; likewise, the unconfirmed 283Rg appears to have a long half-life of about 5.1 minutes. The isotopes 280Rg and 281Rg have also been reported to have half-lives over a second. The remaining isotopes have half-lives in the millisecond range.[64]

The missing isotopes between 274Rg and 278Rg are too light to be produced by hot fusion and too heavy to be produced by cold fusion. A possible synthesis method is to populate them from above, as daughters of nihonium or moscovium isotopes that can be produced by hot fusion.[66] The isotopes 283Rg and 284Rg could be synthesised using charged-particle evaporation, using the 238U+48Ca reaction where a proton is evaporated alongside some neutrons.[67][68]

Predicted properties

[edit]

Other than nuclear properties, no properties of roentgenium or its compounds have been measured; this is due to its extremely limited and expensive production[17] and the fact that roentgenium (and its parents) decays very quickly. Properties of roentgenium metal remain unknown and only predictions are available.

Chemical

[edit]

Roentgenium is the ninth member of the 6d series of transition metals.[69] Calculations on its ionization potentials and atomic and ionic radii are similar to that of its lighter homologue gold, thus implying that roentgenium's basic properties will resemble those of the other group 11 elements, copper, silver, and gold; however, it is also predicted to show several differences from its lighter homologues.[2]

Roentgenium is predicted to be a noble metal. The standard electrode potential of 1.9 V for the Rg3+/Rg couple is greater than that of 1.5 V for the Au3+/Au couple. Roentgenium's predicted first ionisation energy of 1020 kJ/mol almost matches that of the noble gas radon at 1037 kJ/mol.[2] Its predicted second ionization energy, 2070 kJ/mol, is almost the same as that of silver. Based on the most stable oxidation states of the lighter group 11 elements, roentgenium is predicted to show stable +5 and +3 oxidation states, with a less stable +1 state. The +3 state is predicted to be the most stable. Roentgenium(III) is expected to be of comparable reactivity to gold(III), but should be more stable and form a larger variety of compounds. Gold also forms a somewhat stable −1 state due to relativistic effects, and it has been suggested roentgenium may do so as well:[2] nevertheless, the electron affinity of roentgenium is expected to be around 1.6 eV (37 kcal/mol), significantly lower than gold's value of 2.3 eV (53 kcal/mol), so roentgenides may not be stable or even possible.[70]

Diagram of a roentgenium atom with electron shells.

The 6d orbitals are destabilized by relativistic effects and spin–orbit interactions near the end of the fourth transition metal series, thus making the high oxidation state roentgenium(V) more stable than its lighter homologue gold(V) (known only in gold pentafluoride, Au2F10) as the 6d electrons participate in bonding to a greater extent. The spin-orbit interactions stabilize molecular roentgenium compounds with more bonding 6d electrons; for example, RgF−
6 is expected to be more stable than RgF−
4, which is expected to be more stable than RgF−
2.[2] The stability of RgF−
6 is homologous to that of AuF−
6; the silver analogue AgF−
6 is unknown and is expected to be only marginally stable to decomposition to AgF−
4 and F2. Moreover, Rg2F10 is expected to be stable to decomposition, exactly analogous to the Au2F10, whereas Ag2F10 should be unstable to decomposition to Ag2F6 and F2. Gold heptafluoride, AuF7, is known as a gold(V) difluorine complex AuF5·F2, which is lower in energy than a true gold(VII) heptafluoride would be; RgF7 is instead calculated to be more stable as a true roentgenium(VII) heptafluoride, although it would be somewhat unstable, its decomposition to Rg2F10 and F2 releasing a small amount of energy at room temperature.[71] Roentgenium(I) is expected to be difficult to obtain.[2][72][73] Gold readily forms the cyanide complex Au(CN)−
2, which is used in its extraction from ore through the process of gold cyanidation; roentgenium is expected to follow suit and form Rg(CN)−
2.[74]

The probable chemistry of roentgenium has received more interest than that of the two previous elements, meitnerium and darmstadtium, as the valence s-subshells of the group 11 elements are expected to be relativistically contracted most strongly at roentgenium.[2] Calculations on the molecular compound RgH show that relativistic effects double the strength of the roentgenium–hydrogen bond, even though spin–orbit interactions also weaken it by 0.7 eV (16 kcal/mol). The compounds AuX and RgX, where X = F, Cl, Br, O, Au, or Rg, were also studied.[2][75] Rg+ is predicted to be the softest metal ion, even softer than Au+, although there is disagreement on whether it would behave as an acid or a base.[76][77] In aqueous solution, Rg+ would form the aqua ion [Rg(H2O)2]+, with an Rg–O bond distance of 207.1 pm. It is also expected to form Rg(I) complexes with ammonia, phosphine, and hydrogen sulfide.[77]

Physical and atomic

[edit]

Roentgenium is expected to be a solid under normal conditions and to crystallize in the body-centered cubic structure, unlike its lighter congeners which crystallize in the face-centered cubic structure, due to its being expected to have different electron charge densities from them.[3] It should be a very heavy metal with a density of around 22–24 g/cm3; in comparison, the densest known element that has had its density measured, osmium, has a density of 22.61 g/cm3.[4][5] The atomic radius of roentgenium is expected to be around 114 pm.[6]

Experimental chemistry

[edit]

Unambiguous determination of the chemical characteristics of roentgenium has yet to have been established[78] due to the low yields of reactions that produce roentgenium isotopes.[2] For chemical studies to be carried out on a transactinide, at least four atoms must be produced, the half-life of the isotope used must be at least 1 second, and the rate of production must be at least one atom per week.[69] Even though the half-life of 282Rg, the most stable confirmed roentgenium isotope, is 100 seconds, long enough to perform chemical studies, another obstacle is the need to increase the rate of production of roentgenium isotopes and allow experiments to carry on for weeks or months so that statistically significant results can be obtained. Separation and detection must be carried out continuously to separate out the roentgenium isotopes and allow automated systems to experiment on the gas-phase and solution chemistry of roentgenium, as the yields for heavier elements are predicted to be smaller than those for lighter elements. However, the experimental chemistry of roentgenium has not received as much attention as that of the heavier elements from copernicium to livermorium,[2][78][79] despite early interest in theoretical predictions due to relativistic effects on the ns subshell in group 11 reaching a maximum at roentgenium.[2] The isotopes 280Rg and 281Rg are promising for chemical experimentation and may be produced as the granddaughters of the moscovium isotopes 288Mc and 289Mc respectively;[80] their parents are the nihonium isotopes 284Nh and 285Nh, which have already received preliminary chemical investigations.[38]

See also

[edit]

Explanatory notes

[edit]

References

[edit]

General bibliography

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Roentgenium

View on Grokipedia
from Grokipedia
Roentgenium (Rg) is a synthetic with 111, classified as a d-block transactinide in group 11 of the periodic table, situated below , silver, and . It is highly radioactive, with all known isotopes decaying rapidly, and only a handful of atoms have ever been produced in laboratory settings, making it one of the heaviest elements synthesized to date. The element was first synthesized on December 8, 1994, at the GSI Helmholtz Centre for Heavy Ion Research in , , by an international team led by physicist Sigurd Hofmann. This discovery occurred through the bombardment of a target with a beam of nickel-64 ions in the heavy-ion accelerator facility, resulting in the fusion-evaporation reaction that produced three atoms of the isotope roentgenium-272, which decayed via alpha emission with a of approximately 1.6 milliseconds. The International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics (IUPAP) officially recognized the GSI team as the discoverers in 2003, following verification of the experimental data. In honor of Wilhelm Conrad Röntgen, the German physicist who discovered X-rays in 1895 and received the first in 1901, the name roentgenium and symbol Rg were proposed by the discoverers and approved by the IUPAC on November 1, 2004, with the announcement made public on November 8, 2004. This naming adhered to IUPAC guidelines, which prioritize honoring notable scientists and require a period of public review before finalization. Due to relativistic effects in its heavy nucleus and the scarcity of produced atoms, roentgenium's are largely predicted through theoretical models and extrapolations from lighter group 11 elements. It is expected to be a solid at , with a silvery metallic appearance, a body-centered cubic differing from gold's face-centered cubic form, and an extraordinary exceeding that of (the densest naturally occurring element at 22.59 g/cm³). Chemically, roentgenium is anticipated to behave as a similar to , potentially forming stable +1 and +3 oxidation states, with a possible +5 state under specific conditions, and exhibiting volatility in compounds like roentgenium (RgCl₃). Its is predicted as [Rn] 5f¹⁴ 6d¹⁰ 7s¹, supporting these traits. Seven confirmed isotopes of roentgenium have been synthesized, with mass numbers 272, 274, and 278–282; the most stable is roentgenium-282, with a of about 100 seconds, decaying primarily by alpha emission or . Other notable isotopes include roentgenium-272 ( ~1.6 ms) from the initial synthesis, roentgenium-281 ( 22.8 s), and roentgenium-280 ( ~3.6 s), produced in later experiments at facilities like in . These short half-lives preclude any practical applications, though roentgenium contributes to research on superheavy elements, nuclear stability in the "," and .

Introduction

Overview and significance

Roentgenium (Rg) is a synthetic with 111. It belongs to group 11 of the periodic table, positioned below , silver, and , and is expected to exhibit properties typical of a d-block , though its chemical behavior is predicted to deviate due to extreme relativistic effects on its orbitals. Superheavy elements like roentgenium are artificially produced and highly unstable, with half-lives typically measured in seconds or less; however, theoretical models suggest an "" where isotopes near atomic numbers 114–126 and numbers around 184 could have significantly longer half-lives due to enhanced nuclear shell effects. Roentgenium, with Z=111, lies in close proximity to this predicted region, offering insights into the transition toward greater nuclear stability. Roentgenium was first synthesized in December 1994 at the GSI Helmholtz Centre for Heavy Ion Research in , , through the fusion of and nickel-64, producing the ^{272}Rg. Its discovery marked a milestone in extending the periodic table and was officially recognized by the International Union of Pure and Applied Chemistry (IUPAC) in 2004. The significance of roentgenium lies in its role in probing nuclear shell structures, where closed proton and shells enhance stability against fission and decay, as well as in studying relativistic quantum effects that dominate the chemistry of heavy atoms, such as orbital contraction and spin-orbit splitting. These investigations contribute to validating models of and the limits of the periodic table.

Role in superheavy element research

Roentgenium, with atomic number 111, plays a pivotal role in testing nuclear shell models that predict enhanced stability for superheavy nuclei due to closed proton and neutron shells at magic numbers such as Z=114 and N=184. Experimental data from its synthesis and decay have revealed short half-lives, such as 22.8 seconds for the isotope ^{281}Rg, which deviate from theoretical expectations of longer-lived isotopes near the predicted "island of stability" around Z=114–126. These observations help refine shell model parameters, highlighting the influence of deformed shells and the challenges in achieving neutron-rich configurations required to access the island. Studies of roentgenium isotopes contribute significantly to understanding fission barriers and alpha decay mechanisms in superheavy elements, where competition between alpha emission and spontaneous fission dominates decay pathways. Theoretical calculations of alpha decay chains for isotopes ranging from ^{255}Rg to ^{350}Rg predict half-lives spanning milliseconds to seconds, with many undergoing alpha decay followed by fission in daughter nuclei, providing empirical data to validate macroscopic-microscopic models of fission barriers. For instance, isotopes like ^{279}Rg exhibit both alpha decay (branching ratio ~87%) and spontaneous fission, offering insights into barrier heights that decrease with increasing atomic number, thus informing stability limits in the superheavy region. Production of roentgenium remains challenging due to minuscule fusion cross-sections on the order of picobarns—typically around 3.5 pb for ^{272}Rg via the ^{64}Ni + ^{209}Bi reaction—and extremely short half-lives that limit observable yields to a few atoms per experiment. These constraints necessitate advanced facilities like GSI's SHIP separator, where detection efficiency is critical amid high , underscoring the technical hurdles in accumulating sufficient data for nuclear structure analysis. Roentgenium's investigation influences efforts to extend the periodic table beyond element 118, as its nuclear properties guide beam-target combinations and reaction mechanisms for synthesizing heavier elements, potentially revealing new stability trends. Theoretical advancements, including calculations and Skyrme mean-field approaches, link roentgenium decay data—such as chains from ^{279}Rg in the ^{287}Mc series—to neighboring elements like (Z=114) and (Z=115), refining predictions of shell closures at N=152 and N=184 while highlighting the need for neutron-richer isotopes to probe the .

History

Pre-discovery efforts

Theoretical predictions for element 111 emerged in the and as part of broader efforts to extend the periodic table using nuclear shell models. These models, building on the liquid drop model with shell corrections, identified potential "islands of stability" for superheavy elements where closed proton and shells could enhance nuclear binding and half-lives. Myers and Swiatecki's 1966 work, refined in the , predicted closed shells at proton number ≈ 114 and number N = 184, implying relative stability for nearby nuclides including those with = 111. Fiset and Nix (1972) calculated alpha-decay half-lives for isotopes near = 110–114, estimating up to 10^9 years for some, which motivated experimental searches despite the challenges of synthesis. Early experimental attempts focused on fusion-evaporation reactions at major facilities, though yields were extremely low and signals ambiguous. At the (JINR) in , and his team pioneered hot fusion methods in the 1980s, using lighter projectiles like neon-22 or heavier beams on targets to probe regions; while specific claims for element 111 were absent, they reported unconfirmed decay chains suggestive of elements up to Z = 116, often terminating in without clear genetic correlations. These efforts, conducted with cyclotrons like the U-300 and U-400, faced severe limitations from cross-sections below 1 nanobarn and high background radiation, preventing IUPAC recognition. Simultaneously, at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Peter Armbruster and Sigurd Hofmann developed the cold fusion approach using the velocity filter SHIP separator, successfully identifying elements 107–109 in the mid-1980s via reactions like nickel-58 on bismuth-209. Preliminary attempts to extend this to element 111 in the late 1980s and early 1990s involved similar bismuth targets with nickel beams, but detected events were too few and decay signatures too short-lived (milliseconds) for unambiguous identification, compounded by evaporation residue separation efficiencies under 1% and the need for weeks-long irradiations. These challenges, including ambiguous alpha and fission correlations, led to non-recognition by IUPAC until later confirmations. Oganessian's theoretical and experimental leadership at Dubna, alongside GSI's innovations, laid crucial groundwork for superheavy element research despite the initial setbacks.

Official synthesis and confirmation

The first official synthesis of roentgenium (element 111) occurred on December 8, 1994, at the Gesellschaft für Schwerionenforschung (GSI) Helmholtz Centre for Heavy Ion Research in , , where an international team led by Sigurd Hofmann used the velocity filter SHIP to separate and detect fusion products. The experiment involved bombarding a ^{209}Bi target with a beam of ^{64}Ni ions, resulting in the fusion-evaporation reaction ^{209}Bi(^{64}Ni,1n)^{272}Rg, which produced the isotope with a cross-section on the order of 10 picobarns. Three atoms of were detected, each decaying via a chain of alpha emissions: → ^{268}Mt → ^{264}Ds → ^{260}Hs, followed by , providing unambiguous identification through correlated decay signatures measured in position-sensitive detectors. Key contributors to the experiment included , who played a central role in the and detection setup, along with other members of the GSI team such as Fritz P. Heßberger and Gottfried Münzenberg. An independent of the 1994 results came in 2003 from a team at the Nishina Center for Accelerator-Based Science in , led by Kosuke Morita, who replicated the same ^{209}Bi(^{64}Ni,1n)^{272}Rg reaction using the gas-filled recoil separator GARIS. Over multiple irradiation runs, the RIKEN group observed 14 decay chains consistent with ^{272}Rg, including the same sequence to ^{268}Mt, ^{264}Ds, and ^{260}Hs, with improved statistics that corroborated the GSI cross-section and measurements for ^{272}Rg (approximately 1.5 ms). This higher-yield strengthened the evidence by demonstrating across facilities and reducing uncertainties in the decay properties. The discovery was officially recognized by a joint working party of the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics (IUPAP) in 2003, following a detailed review of the experimental data from both GSI and RIKEN, which affirmed the priority of the Hofmann-led GSI team for the synthesis of element 111. This recognition culminated in the approval of the name "roentgenium" (symbol Rg) in 2004, honoring Wilhelm Conrad Röntgen, with the element's properties briefly referenced in subsequent IUPAC nomenclature updates but without altering the established discovery credits.

Naming and recognition

Following its synthesis in 1994, element 111 was temporarily designated by the systematic name ununnunium (symbol Uuu), as per the International Union of Pure and Applied Chemistry (IUPAC) conventions for newly discovered elements lacking permanent names. This placeholder reflected its (1-1-1) and was used in until a formal name could be established. It was occasionally referred to as eka-, an informal term highlighting its predicted position in group 11 of the periodic table, directly below . In 2004, the discovery team at the Gesellschaft für Schwerionenforschung (GSI) in , , proposed the name roentgenium (symbol Rg) to honor the German physicist Wilhelm Conrad Röntgen (1845–1923), who discovered X-rays in 1895 and received the first for this achievement. The proposal adhered to IUPAC guidelines for naming elements after deceased scientists whose contributions had significant impact, emphasizing Röntgen's foundational work in and its influence on and chemistry. The IUPAC Inorganic Chemistry Division reviewed and recommended the proposal, leading to its official adoption on November 1, 2004, as published in Pure and Applied Chemistry. This approval integrated roentgenium into the periodic table as element 111 with the symbol Rg, marking it as the heaviest confirmed element at the time and concluding the naming process without major disputes specific to this case. Broader discussions in nomenclature have included debates on honoring living versus deceased scientists, as well as competing name suggestions like joliotium (proposed for earlier transactinides), but these did not directly affect roentgenium's designation.

Synthesis and Detection

Production techniques

Roentgenium isotopes are produced via cold - reactions using heavy-ion accelerators, where a beam of accelerated ions is directed at a solid target to induce followed by . The established method employs the reaction ^{209}\text{Bi}(^{64}\text{Ni},1n)^{272}\text{Rg}, in which nickel-64 ions fuse with nuclei to form the compound nucleus ^{273}\text{Rg}, which then evaporates a single to yield the isotope ^{272}\text{Rg}. This reaction has a measured cross-section of approximately 1.7^{+3.3}{-1.4} picobarns at a beam of 318 MeV and 3.5^{+4.6}{-2.3} picobarns at 320 MeV in the center-of-mass frame. The experiments are conducted at the GSI Helmholtz Centre for Heavy Ion Research in , , utilizing the UNILAC linear accelerator to deliver beams with intensities around 3 \times 10^{12} particles per second. The target is prepared as a thin layer, typically 450 \mu g/cm^2 thick, evaporated onto a 40 \mu g/cm^2 carbon backing with an 8 \mu g/cm^2 carbon cover foil to withstand the beam power while minimizing energy straggling. Fusion products recoil from the target with velocities matching the center-of-mass velocity and are separated from the intense primary beam using the SHIP (Separator for Heavy Ion Reaction Products) velocity filter, which employs electric and to transmit ions within a narrow velocity window (about 4% \Delta v/v). Implanted recoils are then detected via their in a position-sensitive detector array at SHIP's focal plane. These conditions result in extremely low production rates, with only a handful of ^{272}\text{Rg} atoms observed per multi-week irradiation campaign—for instance, three atoms were detected during the 1994 discovery experiment. Alternative production routes for roentgenium isotopes, aimed at accessing more neutron-rich species, include reactions such as ^{208}\text{Pb}(^{70}\text{Zn},3n)^{275}\text{Rg} or ^{207}\text{Pb}(^{70}\text{Zn},2n)^{275}\text{Rg}, which involve heavier projectiles on lead targets to increase the while maintaining the of 111. These approaches face significant challenges due to the higher from the increased charge of the zinc ions, leading to estimated cross-sections below 1 picobarn and requiring even higher beam intensities for viable yields. Although explored theoretically and in broader campaigns at facilities like GSI, no confirmed production of these isotopes has been reported, limiting their practical use compared to the bismuth-nickel system. Ongoing improvements to the UNILAC in the , as part of preparations for the facility, have enhanced beam transmission and intensity through upgrades to the high-charge-state injector, stripper foil systems, and beam-shaping , achieving up to a factor of three increase in on-target intensity for intermediate-mass ions like . These advancements, including optimized gas stripping to higher charge states (e.g., up to 28+ for ) and flattened beam profiles via octupole magnets, have improved overall efficiency for production, though roentgenium yields remain on the order of a few atoms per experiment due to inherent low cross-sections. The SHIP separator continues to be refined with better focal-plane detectors to handle higher backgrounds from increased beam currents.

Decay chains and identification methods

Roentgenium atoms, produced in heavy-ion fusion reactions, are isolated from the intense beam and lighter reaction products using recoil separators such as the Separator for Heavy Ion reaction Products (SHIP) at GSI Helmholtz Centre for Heavy Ion Research. SHIP employs a velocity filter consisting of crossed electric and to select evaporation residues based on their high relative to scattered beam particles and fission fragments, transmitting only the heavy fusion products to a focal plane detector array over a of approximately 2 μs. Upon transmission, the isolated roentgenium nuclei are implanted into position-sensitive detectors, where their subsequent radioactive decays—primarily , but potentially including or —are registered through energy deposition and precise spatial and temporal s. These detectors, typically double-sided strip detectors (DSSSDs), record the energy of alpha particles (around 10-12 MeV for superheavy elements) or fission fragments (higher energies with characteristic asymmetry), enabling the reconstruction of decay sequences. The position resolution allows of parent-daughter decays occurring in the same detector , confirming the essential for identifying short-lived species. A representative example is the decay chain of the isotope ^{272}Rg, first observed in the reaction ^{209}Bi(^{64}Ni,n)^{272}Rg at SHIP. This isotope undergoes alpha decay to ^{268}Mt with an alpha-particle energy of approximately 11.23 MeV, followed by successive alpha decays through ^{264}Bh, ^{260}Db, and ^{256}Lr, terminating in known isotopes for unambiguous assignment. The full chain is established by measuring the energies and decay times of each step, ensuring consistency with previously characterized lighter nuclei. Identification of roentgenium relies on this genetic correlation, where the observed is matched to sequences of previously identified isotopes of lower-Z elements, providing a unique despite the inability to directly observe the atom itself. Cross-sections for production are inferred from the number of correlated chains relative to beam dose, with early measurements for ^{272}Rg yielding values around 1-3 picobarns. Recent advancements in detection systems, including the adoption of for baseline restoration and , have improved energy and timing resolutions, enabling higher event rates and more reliable correlation of decay chains in experiments at facilities like GSI. These upgrades, implemented in new detector arrays such as SHREC, facilitate the study of even rarer isotopes by reducing noise and enhancing isotopic resolution.

Isotopes

Known isotopes and their properties

Roentgenium has no stable isotopes and all known isotopes are synthetic, produced in ultra-trace quantities through heavy-ion fusion-evaporation reactions or as decay products of heavier superheavy elements. Only a handful of atoms of each isotope have been observed in laboratory experiments, primarily at facilities such as GSI Helmholtz Centre and JINR. The experimentally observed isotopes include ^{272}Rg, ^{274}Rg, ^{278}Rg, ^{279}Rg, ^{280}Rg, ^{281}Rg, and ^{282}Rg, with mass numbers reflecting neutron evaporation channels or alpha decay sequences from parent nuclei. The most studied isotope, ^{272}Rg, was first synthesized directly via the reaction ^{209}Bi(^{64}Ni,1n)^{272}Rg at the GSI SHIP separator, yielding three atoms initially with a cross section on the order of 10^{-36} pb; subsequent experiments at confirmed its production using the same reaction, observing additional atoms. This odd-odd nucleus (Z=111 odd, N=161 odd) is predicted to have spin and parity of 5^{+} or 6^{+} based on considerations consistent with observed decay patterns. Heavier isotopes are typically observed as intermediate products in alpha decay chains from elements 113 () to 117 (), produced via hot fusion reactions involving ^{48}Ca beams on targets. For instance, ^{274}Rg has been identified in decay chains from ^{278}Ds (element 110), accessed through ^{208}Pb(^{70}Zn,0n)^{278}Ds, with only a few events recorded. Similarly, ^{278}Rg appears in sequences from ^{282}Nh (element 113), while ^{279}Rg, ^{280}Rg, ^{281}Rg, and ^{282}Rg emerge from decay chains of moscovium (115) and (117) isotopes like ^{288}Mc and ^{293}Ts, with production yields remaining extremely low due to fission competition in the chains. ^{282}Rg, first observed around 2010 in experiments at JINR, with additional detections in later studies at GSI and JINR, represents one of the neutron-richest confirmed roentgenium isotopes, with a handful of atoms detected in multi-neutron evaporation channels.
IsotopeMass NumberProduction ModeObserved Atoms (Representative)Half-life (approx.)Decay ModeSpin/Parity (Predicted)
^{272}Rg272^{209}Bi(^{64}Ni,1n) ~20 total across experiments1.6 msα5^{+}, 6^{+} (odd-odd)
^{274}Rg274Decay of ^{278}Ds from ^{208}Pb(^{70}Zn,0n)Few events6.4 msαNot specified
^{278}Rg278Decay of ^{282}Nh from ^{233}U(^{48}Ca,3n) or similarFew events4.2 msαNot specified
^{279}Rg279Decay of ^{283}Nh from ^{243}Am(^{48}Ca,4n)Few events0.74 sα1/2^{+} (odd N)
^{280}Rg280Decay of ^{284}Nh/Mc isotopesFew events3.6 sα/SFNot specified
^{281}Rg281Decay of ^{293}TsFew events22.8 sα/SF1/2^{+} (odd N)
^{282}Rg282Decay of ^{294}Ts or ^{290}McFew events~100 sαNot specified
These isotopes exhibit neutron numbers around the N=162-171 shell closure, influencing their basic nuclear properties, though detailed spin assignments are limited by the scarcity of data. Production yields for all are on the picobarn scale or lower, underscoring the challenges in superheavy element research. Theoretical models indicate that neutron-rich isotopes of roentgenium with neutron numbers between 162 and 184 lie near the predicted , where shell closures are expected to enhance nuclear binding and extend half-lives to seconds or even minutes for certain configurations. These predictions stem from analyses of potential long-lived superheavy nuclei, positioning roentgenium as a key element in probing the boundaries of this stability through future synthesis efforts. Macroscopic-microscopic models, which combine liquid-drop macroscopic energies with shell-correction microscopic effects, estimate fission barriers for roentgenium isotopes in the range of approximately 5–7 MeV, providing a measure of resistance against decay. These barriers decrease gradually toward higher atomic numbers but remain sufficient in neutron-rich configurations to support relative stability compared to lighter isotopes. Extrapolations from calculations suggest that more neutron-rich isotopes like ^{286}Rg or ^{290}Rg could exhibit improved stability, with half-lives potentially exceeding those of currently observed roentgenium nuclides, and may be accessible via multi-nucleon transfer reactions in heavy-ion collisions. Such reactions offer a pathway to populate these heavier isotopes beyond traditional fusion-evaporation methods. Recent updates from 2024 relativistic mean-field calculations, incorporating axial deformation, highlight enhanced stability in nuclei due to prolate deformations and shell effects near N=162–184, which could apply to roentgenium by increasing binding energies and delaying fission. These models predict prolonged half-lives in deformed configurations, refining earlier estimates for the region. In comparison to its group 11 homologues (, silver, and ), theoretical trends for elements show half-lives generally decreasing with increasing Z for isotopes with similar neutron content, reflecting heightened repulsion and reduced shell stabilization in heavier systems. This pattern underscores roentgenium's position at the limit of current nuclear stability.

Predicted Properties

Physical and atomic characteristics

Roentgenium is expected to be a solid at and standard pressure, with a predicted of approximately 24 g/cm³, exceeding that of (22.59 g/cm³). It is anticipated to have a silvery metallic appearance and crystallize in a body-centered cubic (bcc) structure, differing from the face-centered cubic (fcc) structure of . The is estimated to be around 700–800 °C. The is predicted to be about 121 pm, and the is [Rn] 5f¹⁴ 6d¹⁰ 7s¹.

Chemical behavior and relativistic effects

Roentgenium is predicted to exhibit the characteristics of a , displaying low reactivity toward common reagents such as oxygen and , and is expected to be even less reactive than its lighter group 11 homologue due to enhanced relativistic stabilization of the valence 7s electrons, which promotes an inert-pair-like where the s electrons are less available for bonding. This stabilization arises from the strong contraction and energy lowering of the 7s orbital due to relativistic effects. Theoretical calculations indicate that the +1 (Rg⁺) is the most stable for roentgenium, consistent with its [Rn] 5f¹⁴ 6d¹⁰ 7s¹ and the relativistic preference for retaining the 7s electron, while the +3 state (Rg³⁺) may be accessible under oxidizing conditions, though less favored than in due to the greater energetic cost of removing d electrons. Some predictions suggest +3 or +5 states may also be possible. Compounds such as roentgenium(I) (Rg₂O) or roentgenium(I) (RgCl) are predicted to be volatile, facilitating potential gas-phase transport in theoretical studies of chemistry, with RgCl showing a potentially lower than that of AuCl owing to weaker metal-ligand interactions. Relativistic effects dominate roentgenium's chemical behavior, particularly through the scalar relativistic contraction and spin-orbit splitting of the 7s and 6d orbitals, which invert the expected energy ordering and enhance the of the element by making donation more difficult. This leads to weaker overall bonding tendencies compared to lighter homologues, as the stabilized 7s orbital reduces orbital overlap in complexes, with the first potential predicted at around 1020 kJ/mol. Recent DFT predictions for roentgenium's aqueous chemistry highlight the Rg⁺ ion as the softest known metal cation according to Pearson's hard-soft acid-base (HSAB) theory, with a global softness parameter exceeding that of Au⁺ by about 20%, implying extremely high thiophilicity and strong affinity for soft ligands like sulfide (log K₁ for [Rg(H₂S)]⁺ ≈ 10.5) over hard ones like water or ammonia. In group 11 homology, roentgenium's filled 6d¹⁰ subshell contributes to more localized electrons and weaker bonds relative to group 10 darmstadtium (Ds, element 110), where incomplete d filling allows for greater covalency; for example, the Rg-CN bond dissociation energy is calculated at 3.57 eV, lower than analogous Ds bonds despite shorter bond lengths due to relativistic contraction.

Experimental Chemistry

Early experimental attempts

No experimental chemical studies have been performed on roentgenium to date, owing to its extreme rarity (only a few atoms produced in total) and short isotopic half-lives (less than 23 seconds for the longest-lived isotope, ^{281}Rg). These constraints preclude the isolation of sufficient material for conventional chemical analysis or the application of spectroscopic techniques. Initial efforts at facilities like the GSI Helmholtz Centre focused on synthesis and nuclear properties rather than chemistry, with single-atom detection limited to decay chain correlations. Theoretical models predict roentgenium's chemical behavior, but relativistic effects in its heavy nucleus complicate direct comparisons to lighter group 11 elements like . Early computational studies suggested potential volatility in compounds such as roentgenium carbonyls, but no empirical verification has been achieved.

Recent investigations and findings

As of November 2025, experimental chemical investigations on roentgenium remain nonexistent due to persistent challenges in production rates and isotopic stability. Advances in single-atom techniques, such as the stopping and separation (SIS) method, have extended observation times to around 10 seconds for some superheavy elements, but roentgenium's isotopes do not permit such durations for chemical probing. Research has instead emphasized theoretical and computational approaches. Density functional theory (DFT) calculations predict roentgenium as a noble metal with a stable +1 oxidation state, enhanced inertness from 7s orbital stabilization, and limited viability for +3 states under standard conditions, aligning it more closely with coinage metals than expected. Proposals for future experiments, including adsorption comparisons on SiO_2 and Au surfaces or cluster formation at JINR and RIKEN, aim to test these predictions empirically once production yields improve.

References

  1. https://periodic-table.rsc.org/element/111/roentgenium
  2. https://pubchem.ncbi.nlm.nih.gov/element/Roentgenium
  3. https://www.gsi.de/en/researchaccelerators/research_an_overview/new_elements
  4. https://www.tandfonline.com/doi/full/10.1080/10506890701225189
  5. https://old.iupac.org/news/archives/2004/naming111.html
  6. https://www.nature.com/articles/s41557-018-0131-7
  7. https://www.americanelements.com/roentgenium.html
  8. https://physicstoday.aip.org/features/a-beachhead-on-the-island-of-stability
  9. https://www.gsi.de/en/work/forschung/nustarenna/nustarenna_divisions/she_physik/research/super_heavy_elements/element_111
  10. https://link.springer.com/article/10.1007/BF01291182
  11. https://pubs.acs.org/doi/10.1021/acs.chemrev.9b00785
  12. https://royalsocietypublishing.org/doi/10.1098/rsta.2019.0305
  13. https://link.aps.org/doi/10.1103/PhysRevC.95.054621
  14. https://doi.org/10.1140/epja/s10050-023-00939-3
  15. https://www.osti.gov/servlets/purl/1221187
  16. http://www.radiochem.org/en/paper/JN41/j041Hofmann.pdf
  17. https://publications.iupac.org/ci/2005/2701/iw1_naming.html
  18. http://publications.iupac.org/pac/76/12/2101/index.html
  19. https://www.researchgate.net/publication/226148803_The_new_element_111
  20. https://www.researchgate.net/publication/299431289_Systematics_of_production_cross_sections_and_predictions_for_the_synthesis_of_new_superheavy_elements
  21. https://accelconf.web.cern.ch/e02/papers/WEPLE118.pdf
  22. https://accelconf.web.cern.ch/linac2022/papers/mopopa18.pdf
  23. https://doi.org/10.1007/BF01291182
  24. https://atom.kaeri.re.kr/cgi-bin/nuclide?nuc=Rg272
  25. https://arxiv.org/pdf/2501.04053
  26. https://linelist.pa.uky.edu/newpage/content/elm111.html
  27. https://arxiv.org/abs/2204.12476
  28. https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2022.965198/full
  29. https://doi.org/10.1103/PhysRevC.100.044618
  30. https://www.europhysicsnews.org/articles/epn/pdf/2002/01/epn02102.pdf
  31. https://www.webelements.com/roentgenium/physics.html
  32. https://www.samaterials.com/blog/roentgenium-element-properties-and-uses.html
  33. https://www.thoughtco.com/roentgenium-facts-rg-or-element-111-3876744
  34. https://chemistry.stackexchange.com/questions/31791/behaviour-of-element-111
  35. https://www.sciencedirect.com/science/article/pii/S0375947415001463
  36. https://www.russchemrev.org/RCR4072pdf
  37. https://www.webelements.com/roentgenium/
  38. https://pubmed.ncbi.nlm.nih.gov/17173436/
  39. https://munin.uit.no/bitstream/handle/10037/13632/article.pdf?sequence=4&isAllowed=y
  40. https://www.researchgate.net/publication/6627510_Density_Functional_Theory-Based_Prediction_of_Some_Aqueous-Phase_Chemistry_of_Superheavy_Element_111_RoentgeniumI_Is_the_Softest_Metal_Ion
  41. https://www.gsi.de/en/work/research/nustarenna/nustarenna_divisions/she_chemistry
  42. https://link.springer.com/article/10.1140/epja/s10050-024-01431-2
Add your contribution
Related Hubs
Contribute something
User Avatar
No comments yet.