Bohrium

From Wikipedia, the free encyclopedia
  (Redirected from Unnilseptium)
Jump to: navigation, search
Not to be confused with Borium, Boron, or Barium.
Bohrium,  107Bh
General properties
Name, symbol bohrium, Bh
Pronunciation Listeni/ˈbɔəriəm/
Bohrium in the periodic table
Hydrogen (diatomic nonmetal)
Helium (noble gas)
Lithium (alkali metal)
Beryllium (alkaline earth metal)
Boron (metalloid)
Carbon (polyatomic nonmetal)
Nitrogen (diatomic nonmetal)
Oxygen (diatomic nonmetal)
Fluorine (diatomic nonmetal)
Neon (noble gas)
Sodium (alkali metal)
Magnesium (alkaline earth metal)
Aluminium (post-transition metal)
Silicon (metalloid)
Phosphorus (polyatomic nonmetal)
Sulfur (polyatomic nonmetal)
Chlorine (diatomic nonmetal)
Argon (noble gas)
Potassium (alkali metal)
Calcium (alkaline earth metal)
Scandium (transition metal)
Titanium (transition metal)
Vanadium (transition metal)
Chromium (transition metal)
Manganese (transition metal)
Iron (transition metal)
Cobalt (transition metal)
Nickel (transition metal)
Copper (transition metal)
Zinc (transition metal)
Gallium (post-transition metal)
Germanium (metalloid)
Arsenic (metalloid)
Selenium (polyatomic nonmetal)
Bromine (diatomic nonmetal)
Krypton (noble gas)
Rubidium (alkali metal)
Strontium (alkaline earth metal)
Yttrium (transition metal)
Zirconium (transition metal)
Niobium (transition metal)
Molybdenum (transition metal)
Technetium (transition metal)
Ruthenium (transition metal)
Rhodium (transition metal)
Palladium (transition metal)
Silver (transition metal)
Cadmium (transition metal)
Indium (post-transition metal)
Tin (post-transition metal)
Antimony (metalloid)
Tellurium (metalloid)
Iodine (diatomic nonmetal)
Xenon (noble gas)
Caesium (alkali metal)
Barium (alkaline earth metal)
Lanthanum (lanthanide)
Cerium (lanthanide)
Praseodymium (lanthanide)
Neodymium (lanthanide)
Promethium (lanthanide)
Samarium (lanthanide)
Europium (lanthanide)
Gadolinium (lanthanide)
Terbium (lanthanide)
Dysprosium (lanthanide)
Holmium (lanthanide)
Erbium (lanthanide)
Thulium (lanthanide)
Ytterbium (lanthanide)
Lutetium (lanthanide)
Hafnium (transition metal)
Tantalum (transition metal)
Tungsten (transition metal)
Rhenium (transition metal)
Osmium (transition metal)
Iridium (transition metal)
Platinum (transition metal)
Gold (transition metal)
Mercury (transition metal)
Thallium (post-transition metal)
Lead (post-transition metal)
Bismuth (post-transition metal)
Polonium (post-transition metal)
Astatine (metalloid)
Radon (noble gas)
Francium (alkali metal)
Radium (alkaline earth metal)
Actinium (actinide)
Thorium (actinide)
Protactinium (actinide)
Uranium (actinide)
Neptunium (actinide)
Plutonium (actinide)
Americium (actinide)
Curium (actinide)
Berkelium (actinide)
Californium (actinide)
Einsteinium (actinide)
Fermium (actinide)
Mendelevium (actinide)
Nobelium (actinide)
Lawrencium (actinide)
Rutherfordium (transition metal)
Dubnium (transition metal)
Seaborgium (transition metal)
Bohrium (transition metal)
Hassium (transition metal)
Meitnerium (unknown chemical properties)
Darmstadtium (unknown chemical properties)
Roentgenium (unknown chemical properties)
Copernicium (transition metal)
Ununtrium (unknown chemical properties)
Flerovium (post-transition metal)
Ununpentium (unknown chemical properties)
Livermorium (unknown chemical properties)
Ununseptium (unknown chemical properties)
Ununoctium (unknown chemical properties)
Re

Bh

(Upe)
seaborgiumbohriumhassium
Atomic number 107
Standard atomic weight [270]
Element category transition metal
Group, block group 7, d-block
Period period 7
Electron configuration [Rn] 5f14 6d5 7s2 (calculated)[1][2]
per shell 2, 8, 18, 32, 32, 13, 2 (predicted)
Physical properties
Phase solid (predicted)[3]
Density near r.t. 37.1 g·cm−3 (predicted)[2][4]
Atomic properties
Oxidation states 7, (5), (4), (3)[2][4] ​(parenthesized oxidation states are predictions)
Ionization energies 1st: 742.9 kJ·mol−1
2nd: 1688.5 kJ·mol−1
3rd: 2566.5 kJ·mol−1
(more) (all estimated)[2]
Atomic radius empirical: 128 pm (predicted)[2]
Covalent radius 141 pm (estimated)[5]
Miscellanea
Crystal structure hexagonal close-packed (hcp)
Hexagonal close-packed crystal structure for bohrium

(predicted)[3]
CAS number 54037-14-8
History
Naming after Niels Bohr
Discovery Gesellschaft für Schwerionenforschung (1981)
Most stable isotopes
Main article: Isotopes of bohrium
iso NA half-life DM DE (MeV) DP
274Bh syn ~54 s[6] α 8.8 270Db
272Bh syn 9.8 s α 9.02 268Db
271Bh syn 1.2 s[7] α 9.35[7] 267Db
270Bh syn 61 s α 8.93 266Db
267Bh syn 17 s α 8.83 263Db
· references

Bohrium is a chemical element with symbol Bh and atomic number 107. It is named after Danish physicist Niels Bohr. It is a synthetic element (an element that can be created in a laboratory but is not found in nature) and radioactive; the most stable known isotope, 270Bh, has a half-life of approximately 61 seconds.

In the periodic table of the elements, it is a d-block transactinide element. It is a member of the 7th period and belongs to the group 7 elements. Chemistry experiments have confirmed that bohrium behaves as the heavier homologue to rhenium in group 7. The chemical properties of bohrium are characterized only partly, but they compare well with the chemistry of the other group 7 elements.

History[edit]

The element 107 was originally proposed to be named after Niels Bohr, a Danish nuclear physicist, with the name nielsbohrium (Ns). This name was later changed by IUPAC to bohrium (Bh).

Official discovery[edit]

Bohrium was first convincingly synthesized in 1981 by a German research team led by Peter Armbruster and Gottfried Münzenberg at the Institute for Heavy Ion Research (Gesellschaft für Schwerionenforschung) in Darmstadt. The team bombarded a target of bismuth-209 with accelerated nuclei of chromium-54 to produce 5 atoms of the isotope bohrium-262:[8]

209
83
Bi
+ 54
24
Cr
262
107
Bh
+ n

The IUPAC/IUPAP Transfermium Working Group (TWG) recognised the GSI collaboration as official discoverers in their 1992 report.[9]

Proposed names[edit]

The German group suggested the name nielsbohrium with symbol Ns to honor the Danish physicist Niels Bohr. The Soviet scientists at the Joint Institute for Nuclear Research in Dubna, Russia had suggested this name be given to element 105 (which was finally called dubnium) and the German team wished to recognise both Bohr and the fact that the Dubna team had been the first to propose the cold fusion reaction to solve the controversial problem of the naming of element 105. The Dubna team agreed with the German group's naming proposal for element 107.[10]

There was an element naming controversy as to what the elements from 104 to 106 were to be called; the IUPAC adopted unnilseptium (symbol Uns) as a temporary, systematic element name for this element.[11] In 1994 a committee of IUPAC recommended that element 107 be named bohrium, not nielsbohrium, since there was no precedence for using a scientist's complete name in the naming of an element.[11][12] This was opposed by the discoverers as there was some concern that the name might be confused with boron and in particular the distinguishing of the names of their respective oxyanions, bohrate and borate. The matter was handed to the Danish branch of IUPAC which, despite this, voted in favour of the name bohrium, and thus the name bohrium for element 107 was recognized internationally in 1997.[11] The IUPAC subsequently decided that bohrium salts should be called bohriates instead of bohrates[citation needed].

Isotopes[edit]

Main article: Isotopes of bohrium
List of bohrium isotopes
Isotope
Half-life
[13][14]
Decay
mode[13][14]
Discovery
year
Reaction
260Bh 35 ms α 2007 209Bi(52Cr,n)[15]
261Bh 11.8 ms α 1986 209Bi(54Cr,2n)[16]
262Bh 84 ms α 1981 209Bi(54Cr,n)[8]
262mBh 9.6 ms α 1981 209Bi(54Cr,n)[8]
263Bh 0.2? ms α ? unknown
264Bh 0.97 s α 1994 272Rg(—,2α)[17]
265Bh 0.9 s α 2004 243Am(26Mg,4n)[18]
266Bh 0.9 s α 2000 249Bk(22Ne,5n)[19]
267Bh 17 s α 2000 249Bk(22Ne,4n)[19]
268Bh 25? s α, SF? unknown
269Bh 25? s α ? unknown
270Bh 61 s α 2006 282Uut(—,3α)[20]
271Bh 1.2 s α 2003 287Uup(—,4α)[20]
272Bh 9.8 s α 2005 288Uup(—,4α)[20]
273Bh 90? min α, SF ? unknown
274Bh ~54 s α 2009 294Uus(—,5α)[6]
275Bh 40? min SF ? unknown

Bohrium has no stable or naturally-occurring isotopes. Several radioactive isotopes have been synthesized in the laboratory, either by fusing two atoms or by observing the decay of heavier elements. Eleven different isotopes of bohrium have been reported with atomic masses 260–262, 264–267, 270–272, 274, one of which, bohrium-262, has a known metastable state. All of these decay only through alpha decay, although some unknown bohrium isotopes are predicted to undergo spontaneous fission.[13]

Stability and half-lives[edit]

The lighter isotopes usually have shorter half-lives; half-lives of under 100 ms for 260Bh, 261Bh, 262Bh, and 262mBh were observed. 264Bh, 265Bh, 266Bh, and 271Bh are more stable at around 1 s, and 267Bh and 272Bh have half-lives of about 10 s. The heaviest isotopes are the most stable, with 270Bh and 274Bh having measured half-lives of about 61 s and 54 s respectively. The unknown isotopes 273Bh and 275Bh are predicted to have even longer half-lives of around 90 minutes and 40 minutes respectively. Before its discovery, 274Bh was also predicted to have a long half-life of 90 minutes, but it was found to have a shorter half-life of only about 54 seconds.[13]

The proton-rich isotopes with masses 260, 261, and 262 were directly produced by cold fusion, those with mass 262 and 264 were reported in the decay chains of meitnerium and roentgenium, while the neutron-rich isotopes with masses 265, 266, 267 were created in irradiations of actinide targets. The four most neutron-rich ones with masses 270, 271, 272, and 274 appear in the decay chains of 282113, 287115, 288115, and 294117 respectively. These eleven isotopes have half-lives ranging from 8 miliseconds to 1 minute.[21]

Chemical properties[edit]

Extrapolated[edit]

Bohrium is the fourth member of the 6d series of transition metals and the heaviest member of group VII in the Periodic Table, below manganese, technetium and rhenium. All the members of the group readily portray their group oxidation state of +7 and the state becomes more stable as the group is descended. Thus bohrium is expected to form a stable +7 state. Technetium also shows a stable +4 state whilst rhenium exhibits stable +4 and +3 states. Bohrium may therefore show these lower states as well.

The heavier members of the group are known to form volatile heptoxides M2O7, so bohrium should also form the volatile oxide Bh2O7. The oxide should dissolve in water to form perbohric acid, HBhO4. Rhenium and technetium form a range of oxyhalides from the halogenation of the oxide. The chlorination of the oxide forms the oxychlorides MO3Cl, so BhO3Cl should be formed in this reaction. Fluorination results in MO3F and MO2F3 for the heavier elements in addition to the rhenium compounds ReOF5 and ReF7. Therefore, oxyfluoride formation for bohrium may help to indicate eka-rhenium properties.

Bohrium is expected to be a solid under normal conditions and assume a hexagonal close-packed crystal structure (c/a = 1.62), similar to its lighter congener rhenium.[3]

Experimental[edit]

In 1995, the first report on attempted isolation of the element was unsuccessful.[22]

In 2000, it was confirmed that although relativistic effects are important, the 107th element does behave like a typical group 7 element.[23]

In 2000, a team at the PSI conducted a chemistry reaction using atoms of 267Bh produced in the reaction between 249Bk and 22Ne ions. The resulting atoms were thermalised and reacted with a HCl/O2 mixture to form a volatile oxychloride. The reaction also produced isotopes of its lighter homologues, technetium (as 108Tc) and rhenium (as 169Re). The isothermal adsorption curves were measured and gave strong evidence for the formation of a volatile oxychloride with properties similar to that of rhenium oxychloride. This placed bohrium as a typical member of group 7.[24]

2 Bh + 3 O
2
+ 2 HCl → 2 BhO
3
Cl
+ H
2
Formula Name(s)
BhO3Cl bohrium oxychloride ; bohrium(VII) chloride trioxide

See also[edit]


References[edit]

  1. ^ Johnson, E.; Fricke, B.; Jacob, T.; Dong, C. Z.; Fritzsche, S.; Pershina, V. (2002). "Ionization potentials and radii of neutral and ionized species of elements 107 (bohrium) and 108 (hassium) from extended multiconfiguration Dirac–Fock calculations". The Journal of Chemical Physics 116: 1862. Bibcode:2002JChPh.116.1862J. doi:10.1063/1.1430256. 
  2. ^ a b c d e Haire, Richard G. (2006). "Transactinides and the future elements". In Morss; Edelstein, Norman M.; Fuger, Jean. The Chemistry of the Actinide and Transactinide Elements (3rd ed.). Dordrecht, The Netherlands: Springer Science+Business Media. ISBN 1-4020-3555-1. 
  3. ^ a b c Östlin, 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. 
  4. ^ a b Fricke, Burkhard (1975). "Superheavy elements: a prediction of their chemical and physical properties". Recent Impact of Physics on Inorganic Chemistry 21: 89–144. doi:10.1007/BFb0116498. Retrieved 4 October 2013. 
  5. ^ Chemical Data. Bohrium - Bh, Royal Chemical Society
  6. ^ a b Oganessian, Y. T.; Abdullin, F. S.; 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. PMID 20481935.  edit (gives life-time of 1.3 min based on a single event; conversion to half-life is done by multiplying with ln(2).)
  7. ^ a b FUSHE (2012). "Synthesis of SH-nuclei". Retrieved September 2012. 
  8. ^ a b c Münzenberg, G.; Hofmann, S.; Heßberger, F.P.; Reisdorf, W.; Schmidt, K.H.; Schneider, J.H.R.; Armbruster, P.; Sahm, C.C.; Thuma, B. (1981). "Identification of element 107 by α correlation chains". Zeitschrift für Physik a Atoms and Nuclei 300 (1): 107–8. Bibcode:1981ZPhyA.300..107M. doi:10.1007/BF01412623. Retrieved 19 November 2012.  edit
  9. ^ Barber, R. C.; Greenwood, N.N.; Hrynkiewicz, A.Z.; Jeannin, Y.P.; Lefort, M.; Sakai, M.; Ulehla, I.; Wapstra, A.P.; Wilkinson, D.H. (1993). "Discovery of the transfermium elements. Part II: Introduction to discovery profiles. Part III: Discovery profiles of the transfermium elements". Pure and Applied Chemistry 65 (8): 1757. doi:10.1351/pac199365081757.  edit
  10. ^ Ghiorso, A.; Seaborg, G.T.; Organessian, Yu. Ts.; Zvara, I.; Armbruster, P.; Hessberger, F.P.; Hofmann, S.; Leino, M.; Munzenberg, G.; Reisdorf, W.; Schmidt, K.-H. (1993). "Responses on 'Discovery of the transfermium elements' by Lawrence Berkeley Laboratory, California; Joint Institute for Nuclear Research, Dubna; and Gesellschaft fur Schwerionenforschung, Darmstadt followed by reply to responses by the Transfermium Working Group". Pure and Applied Chemistry 65 (8): 1815–1824. doi:10.1351/pac199365081815.  edit
  11. ^ a b c "Names and symbols of transfermium elements (IUPAC Recommendations 1997)". Pure and Applied Chemistry 69 (12): 2471. 1997. doi:10.1351/pac199769122471. 
  12. ^ "Names and symbols of transfermium elements (IUPAC Recommendations 1994)". Pure and Applied Chemistry 66 (12): 2419. 1994. doi:10.1351/pac199466122419. 
  13. ^ a b c d Sonzogni, Alejandro. "Interactive Chart of Nuclides". National Nuclear Data Center: Brookhaven National Laboratory. Retrieved 2008-06-06. 
  14. ^ a b Gray, Theodore (2002–2010). "The Photographic Periodic Table of the Elements". periodictable.com. Retrieved 16 November 2012. 
  15. ^ Nelson, S.; Gregorich, K.; Dragojević, I.; Garcia, M.; Gates, J.; Sudowe, R.; Nitsche, H. (2008). "Lightest Isotope of Bh Produced via the Bi209(Cr52,n)Bh260 Reaction". Physical Review Letters 100 (2). Bibcode:2008PhRvL.100b2501N. doi:10.1103/PhysRevLett.100.022501. 
  16. ^ Münzenberg, G.; Armbruster, P.; Hofmann, S.; Heßberger, F. P.; Folger, H.; Keller, J. G.; Ninov, V.; Poppensieker, K. et al. (1989). "Element 107". Zeitschrift für Physik A 333 (2): 163. Bibcode:1989ZPhyA.333..163M. doi:10.1007/BF01565147. 
  17. ^ Hofmann, S.; Ninov, V.; Heßberger, F. P.; Armbruster, P.; Folger, H.; Münzenberg, G.; Schött, H. J.; Popeko, A. G.; Yeremin, A. V.; Andreyev, A. N.; Saro, S.; Janik, R.; Leino, M. (1995). "The new element 111". Zeitschrift für Physik A 350 (4): 281. Bibcode:1995ZPhyA.350..281H. doi:10.1007/BF01291182.  edit
  18. ^ Gan, Z.G.; Guo, J.S.; Wu, X. L.; Qin, Z.; Fan, H.M.; Lei, X.G.; Liu, H.Y.; Guo, B. et al. (2004). "New isotope 265Bh". The European Physical Journal A 20 (3): 385. Bibcode:2004EPJA...20..385G. doi:10.1140/epja/i2004-10020-2. 
  19. ^ a b Wilk, P. A.; Gregorich, KE; Turler, A; Laue, CA; Eichler, R; Ninov V, V; Adams, JL; Kirbach, UW et al. (2000). "Evidence for New Isotopes of Element 107: 266Bh and 267Bh". Physical Review Letters 85 (13): 2697–700. Bibcode:2000PhRvL..85.2697W. doi:10.1103/PhysRevLett.85.2697. PMID 10991211. 
  20. ^ a b c Oganessian, Yu. Ts.; Penionzhkevich, Yu. E.; Cherepanov, E. A. (2007). "Heaviest Nuclei Produced in 48Ca-induced Reactions (Synthesis and Decay Properties)". "AIP Conference Proceedings" 912. p. 235. doi:10.1063/1.2746600. 
  21. ^ Münzenberg, G.; Gupta, M. (2011). "Production and Identification of Transactinide Elements". "Handbook of Nuclear Chemistry". p. 877. doi:10.1007/978-1-4419-0720-2_19. ISBN 978-1-4419-0719-6. 
  22. ^ Malmbeck, R.; Skarnemark, G.; Alstad, J.; Fure, K.; Johansson, M.; Omtvedt, J. P. (2000). Journal of Radioanalytical and Nuclear Chemistry 246 (2): 349. doi:10.1023/A:1006791027906. 
  23. ^ Gäggeler, H. W.; Eichler, R.; Brüchle, W.; Dressler, R.; Düllmann, Ch.E.; Eichler, B.; Gregorich, K. E.; Hoffman, D. C. et al. (2000). "Chemical characterization of bohrium (element 107)". Nature 407 (6800): 63–5. doi:10.1038/35024044. PMID 10993071. 
  24. ^ "Gas chemical investigation of bohrium (Bh, element 107)", Eichler et al., GSI Annual Report 2000. Retrieved on 2008-02-29

External links[edit]