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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 states(−1), (+1), (+3), (+5), (+7) (predicted)[2][6][7]
Ionization energies
  • 1st: 1020 kJ/mol
  • 2nd: 2070 kJ/mol
  • 3rd: 3080 kJ/mol
  • (more) (all estimated)[2]
Atomic radiusempirical: 138 pm (predicted)[2][6]
Covalent radius121 pm (estimated)[8]
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[9] Decay
abun­dance half-life (t1/2) mode pro­duct
279Rg synth 0.09 s[10] α87% 275Mt
SF13% –
280Rg synth 3.9 s α 276Mt
281Rg synth 11 s[11] SF86% –
α14% 277Mt
282Rg synth 2 min[12] α 278Mt
283Rg synth 5.1 min?[13] SF –
286Rg synth 10.7 min?[14] α 282Mt
 Category: Roentgenium
| references

Unununium (/[invalid input: 'roentgenium2009.ogg']rʌntˈɡɛniəm/ runt-GEN-ee-əm or /rɛntˈɡɛniəm/ rent-GEN-ee-əm) is a synthetic radioactive chemical element with the symbol Uuu and atomic number 111. It is placed as the heaviest member of the group 11 (IB) elements, although a sufficiently stable isotope has not yet been produced in a sufficient amount that would confirm this position as a heavier homologue of gold.

Unununium was first observed in 1994 and several isotopes have been synthesized since its discovery. The most stable known isotope is 281Uuu with a half-life of ~20 seconds, which decays by spontaneous fission, like many other N=170 isotones.

History

Official discovery

Unununium was officially discovered by an international team led by Sigurd Hofmann at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany on December 8, 1994.[15] Only three atoms of it were observed (all 272Rg), by the cold fusion between nickel ions and a bismuth target in a linear accelerator:

The element link does not exist. + The element link does not exist. → 272
111Rg
 + 1
0n

In 2001, the IUPAC/IUPAP Joint Working Party (JWP) concluded that there was insufficient evidence for the discovery at that time.[16] The GSI team repeated their experiment in 2002 and detected a three more atoms.[17][18] In their 2003 report, the JWP decided that the GSI team should be acknowledged for the discovery of this element.[19]

Naming

The name roentgenium (Rg) was proposed by the GSI team[20] in honor of the German physicist Wilhelm Conrad Röntgen, and was accepted as a permanent name on November 1, 2004.[21] Unfortunately, Roentgen then rose from the dead and confronted Sigurd Hoffmann, leader of the GSI team, saying that he had had to give up all his worldly honours already and did not wish to go to more trouble. As a result, the element is still known as unununium (Uuu).

Isotopes and nuclear properties

Nucleosynthesis

Target-projectile combinations leading to Z=111 compound nuclei

The below table contains various combinations of targets and projectiles (both at max no. of neutrons) which could be used to form compound nuclei with Z=111.

Target Projectile CN Attempt result
208Pb 65Cu 273Uuu Successful reaction
209Bi 64Ni 273Uuu Successful reaction
232Th 45Sc 277Uuu Reaction yet to be attempted
231Pa 48Ca 279Uuu Reaction yet to be attempted
238U 41K 280Uuu Reaction yet to be attempted
237Np 40Ar 277Uuu Reaction yet to be attempted
244Pu 37Cl 281Uuu Reaction yet to be attempted
243Am 36S 279Uuu Reaction yet to be attempted
248Cm 31P 279Uuu Reaction yet to be attempted
249Bk 30Si 279Uuu Reaction yet to be attempted
249Cf 27Al 276Uuu Reaction yet to be attempted

Cold fusion

This section deals with the synthesis of nuclei of unununium by so-called "cold" fusion reactions. These are processes which create compound nuclei at low excitation energy (~10–20 MeV, hence "cold"), leading to a higher probability of survival from fission. The excited nucleus then decays to the ground state via the emission of one or two neutrons only.

209Bi(64Ni,xn)273−xUuu (x=1)

First experiments to synthesize unununium were performed by the Dubna team in 1986 using this cold fusion reaction. No atoms were identified that could be assigned to atoms of unununium and a production cross-section limit of 4 pb was determined. After an upgrade of their facilities, the team at GSI successfully detected 3 atoms of 272Uuu in their discovery experiment.[15] A further 3 atoms were synthesized in 2000.[17] The discovery of unununium was confirmed in 2003 when a team at RIKEN measured the decays of 14 atoms of 272Uuu during the measurement of the 1n excitation function.[22]

208Pb(65Cu,xn)273−xUuu (x=1)

In 2004, as part of their study of odd-Z projectiles in cold fusion reactions, the team at LBNL detected a single atom of 272Uuu in this new reaction.[23][24]

As a decay product

Isotopes of unununium have also been observed in the decay of heavier elements. Observations to date are outlined in the table below:

Evaporation residue Observed Uuu isotope
288Uup 280Uuu [25]
287Uup 279Uuu [25]
282Uut 278Uuu [26]
278Uut 274Uuu [26]

Chronology of isotope discovery

Isotope Year discovered Discovery reaction
272Uuu 1994 209Bi(64Ni,n)
273Uuu unknown
274Uuu 2004 209Bi(70Zn,n) [26]
275Uuu unknown
276Uuu unknown
277Uuu unknown
278Uuu 2006 237Np(48Ca,3n) [26]
279Uuu 2003 243Am(48Ca,4n) [25]
280Uuu 2003 243Am(48Ca,3n) [25]
281Uuu 2009 249Bk(48Ca,4n)[dubious – discuss]
282Uuu 2009 249Bk(48Ca,3n)[dubious – discuss]

Nuclear isomerism

274Uuu

Two atoms of 274Uuu have been observed in the decay chains starting with 278Uut. The two events occur with different energies and with different lifetimes. In addition, the two entire decay chains appear to be different. This suggests the presence of two isomeric levels but further research is required.

272Uuu

The direct production of 272Uuu has provided four alpha lines at 11.37, 11.03, 10.82, and 10.40 MeV. The GSI measured a half-life of 1.6 ms whilst recent data from RIKEN have given a half-life of 3.8 ms. The conflicting data may be due to isomeric levels but the current data are insufficient to come to any firm assignments.

Chemical yields of isotopes

Cold fusion

The table below provides cross-sections and excitation energies for cold fusion reactions producing unununium isotopes directly. Data in bold represent maxima derived from excitation function measurements. + represents an observed exit channel.

Projectile Target CN 1n 2n 3n
64Ni 209Bi 273Uuu 3.5 pb, 12.5 MeV
65Cu 208Pb 273Uuu 1.7 pb, 13.2 MeV

Chemical properties

Electronic structure (relativistic)

The stable group 11 elements, copper, silver, and gold all have an outer electron configuration nd10(n+1)s1. For each of these elements, the first excited state of their atoms has a configuration nd9(n+1)s2. Due to spin-orbit coupling between the d electrons, this state is split into a pair of energy levels. For copper, the difference in energy between the ground state and lowest excited state causes the metal to appear reddish. For silver, the energy gap widens and it becomes silvery. However, as Z increases, the excited levels are stabilized by relativistic effects and in gold the energy gap decreases again and it appears gold. For unununium, calculations indicate that the 6d97s2 level is stabilized to such an extent that it becomes the ground state. The resulting energy difference between the new ground state and the first excited state is similar to that of silver and unununium is expected to be silvery in appearance.[27]

Extrapolated chemical properties

Oxidation states

Unununium is projected to be the ninth member of the 6d series of transition metals and the heaviest member of group 11 (IB) in the Periodic Table, below copper, silver, and gold. Each of the members of this group show different stable states. Copper forms a stable +2 state, while silver is predominantly found as silver(I) and gold as gold(III). Copper(I) and silver(II) are also relatively well-known. Unununium is therefore expected to predominantly form a stable +3 state.

Chemistry

The heavier members of this group are well known for their lack of reactivity or noble character. Silver and gold are both inert to oxygen, but are attacked by the halogens. In addition, silver is attacked by sulfur and hydrogen sulfide, highlighting its higher reactivity compared to gold. Unununium is expected to be even more noble than gold and can be expected to be inert to oxygen and halogens. The most-likely reaction is with fluorine to form a trifluoride, UuuF3.

See also

References

  1. ^ Turler, A. (2004). "Gas Phase Chemistry of Superheavy Elements" (PDF). Journal of Nuclear and Radiochemical Sciences. 5 (2): R19–R25. doi:10.14494/jnrs2000.5.R19.
  2. ^ a b c d Hoffman, Darleane C.; Lee, Diana M.; Pershina, Valeria (2006). "Transactinides and the future elements". In Morss; Edelstein, Norman M.; Fuger, Jean (eds.). The Chemistry of the Actinide and Transactinide Elements (3rd ed.). Dordrecht, The Netherlands: Springer Science+Business Media. ISBN 978-1-4020-3555-5.
  3. ^ a b Östlin, A.; Vitos, L. (2011). "First-principles calculation of the structural stability of 6d transition metals". Physical Review B. 84 (11): 113104. Bibcode:2011PhRvB..84k3104O. doi:10.1103/PhysRevB.84.113104.
  4. ^ Gyanchandani, Jyoti; Sikka, S. K. (10 May 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. Bibcode:2011PhRvB..83q2101G. doi:10.1103/PhysRevB.83.172101.
  5. ^ Kratz; Lieser (2013). Nuclear and Radiochemistry: Fundamentals and Applications (3rd ed.). p. 631.
  6. ^ a b Fricke, Burkhard (1975). "Superheavy elements: a prediction of their chemical and physical properties". Recent Impact of Physics on Inorganic Chemistry. Structure and Bonding. 21: 89–144. doi:10.1007/BFb0116498. ISBN 978-3-540-07109-9. Retrieved 4 October 2013.
  7. ^ Conradie, Jeanet; Ghosh, Abhik (15 June 2019). "Theoretical Search for the Highest Valence States of the Coinage Metals: Roentgenium Heptafluoride May Exist". Inorganic Chemistry. 2019 (58): 8735–8738. doi:10.1021/acs.inorgchem.9b01139. PMID 31203606. S2CID 189944098.
  8. ^ Chemical Data. Roentgenium - Rg, Royal Chemical Society
  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. ^ http://www.jinr.ru/posts/both-neutron-properties-and-new-results-at-she-factory/
  11. ^ Oganessian, Yuri Ts.; Abdullin, F. Sh.; Alexander, C.; Binder, J.; et al. (2013-05-30). "Experimental studies of the 249Bk + 48Ca reaction including decay properties and excitation function for isotopes of element 117, and discovery of the new isotope 277Mt". Physical Review C. 87 (054621). American Physical Society. Bibcode:2013PhRvC..87e4621O. doi:10.1103/PhysRevC.87.054621.
  12. ^ Khuyagbaatar, J.; Yakushev, A.; Düllmann, Ch. E.; et al. (2014). "48Ca+249Bk Fusion Reaction Leading to Element Z=117: Long-Lived α-Decaying 270Db and Discovery of 266Lr". Physical Review Letters. 112 (17): 172501. Bibcode:2014PhRvL.112q2501K. doi:10.1103/PhysRevLett.112.172501. PMID 24836239.
  13. ^ Hofmann, S.; Heinz, S.; Mann, R.; et al. (2016). "Remarks on the Fission Barriers of SHN and Search for Element 120". In Peninozhkevich, Yu. E.; Sobolev, Yu. G. (eds.). Exotic Nuclei: EXON-2016 Proceedings of the International Symposium on Exotic Nuclei. Exotic Nuclei. pp. 155–164. doi:10.1142/9789813226548_0024. ISBN 9789813226555.
  14. ^ Hofmann, S.; Heinz, S.; Mann, R.; et al. (2016). "Review of even element super-heavy nuclei and search for element 120". The European Physics Journal A. 2016 (52): 180. Bibcode:2016EPJA...52..180H. doi:10.1140/epja/i2016-16180-4. S2CID 124362890.
  15. ^ a b Hofmann, S.; Ninov, V.; Heßberger, F. P.; Armbruster, P.; Folger, H.; Münzenberg, G.; Schött, H. J.; Popeko, A. G.; Yeremin, A. V. (1995). "The new element 111". Zeitschrift für Physik a Hadrons and Nuclei. 350: 281. doi:10.1007/BF01291182.
  16. ^ Karol; Nakahara, H.; Petley, B. W.; Vogt, E.; et al. (2001). "On the discovery of the elements 110–112" (PDF). Pure Appl. Chem. 73 (6): 959–967. doi:10.1351/pac200173060959. {{cite journal}}: Explicit use of et al. in: |author= (help)
  17. ^ a b Hofmann, S.; Heßberger, F.P.; Ackermann, D.; Münzenberg, G.; Antalic, S.; Cagarda, P.; Kindler, B.; Kojouharova, J.; Leino, M. (2002). "New results on elements 111 and 112". The European Physical Journal A. 14: 147. doi:10.1140/epja/i2001-10119-x.
  18. ^ Hofmann; et al. "New results on element 111 and 112" (PDF). GSI report 2000. Retrieved 2008-03-02. {{cite news}}: Explicit use of et al. in: |author= (help)
  19. ^ "Karol et al" (PDF). Pure Appl. Chem. 75 (10): 1601–1611. 2003.
  20. ^ Corish; et al. "Name and symbol of the element with atomic number 111" (PDF). IUPAC Provisional Recommendations. Retrieved 2008-03-02. {{cite news}}: Explicit use of et al. in: |author= (help)
  21. ^ Corish; Rosenblatt, G. M.; et al. (2004). "Name and symbol of the element with atomic number 111" (PDF). Pure Appl. Chem. 76 (12): 2101–2103. doi:10.1351/pac200476122101. {{cite journal}}: Explicit use of et al. in: |author= (help)
  22. ^ Morita, K; Morimoto, K; Kaji, D; Goto, S; Haba, H; Ideguchi, E; Kanungo, R; Katori, K; Koura, H (2004). "Status of heavy element research using GARIS at RIKEN". Nuclear Physics A. 734: 101. doi:10.1016/j.nuclphysa.2004.01.019.
  23. ^ Folden, C. M. (2004). "Development of an Odd-Z-Projectile Reaction for Heavy Element Synthesis: ^{208}Pb(^{64}Ni,n)^{271}Ds and ^{208}Pb(^{65}Cu,n)^{272}111". Physical Review Letters. 93 (21): 212702. doi:10.1103/PhysRevLett.93.212702. PMID 15601003.
  24. ^ "Development of an Odd-Z-Projectile Reaction for Heavy Element Synthesis: 208Pb(64Ni,n)271Ds and 208Pb(65Cu,n)272111", Folden et al., LBNL repositories. Retrieved on 2008-03-02
  25. ^ a b c d see ununpentium for details
  26. ^ a b c d see ununtrium for details
  27. ^ Turler, A. (2004). "Gas Phase Chemistry of Superheavy Elements" (PDF). Journal of Nuclear and Radiochemical Sciences. 5 (2): R19–R25.

External links

source: https://en.wikipedia.org/w/index.php?title=Roentgenium&oldid=421792854

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