Ununpentium: Wikis

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ununquadiumununpentiumununhexium
Bi

Uup

(Uhp)
Appearance
unknown
General properties
Name, symbol, number ununpentium, Uup, 115
Element category unknown
Group, period, block 157, p
Standard atomic weight [288]g·mol−1
Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p3
(guess based on bismuth)
Electrons per shell 2, 8, 18, 32, 32, 18, 5 (Image)
Physical properties
Atomic properties
Miscellanea
CAS registry number 54085-64-2
Most stable isotopes
Main article: Isotopes of ununpentium
iso NA half-life DM DE (MeV) DP
290Uup syn α 286Uut
289Uup syn α 285Uut
288Uup syn 87.5 ms α 10.46 284Uut
287Uup syn 32 ms α 10.59 283Uut
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Ununpentium (pronounced /uːnuːnˈpɛntiəm/ ( listen)[1] oon-oon-PEN-tee-əm) is the temporary name of a synthetic superheavy element in the periodic table that has the temporary symbol Uup and has the atomic number 115.

It is placed as the heaviest member of group 15 (VA) although a sufficiently stable isotope is not known at this time that would allow chemical experiments to confirm its position. It was first observed in 2003 and only about 30 atoms of ununpentium have been synthesized to date, with just 4 direct decays of the parent element having been detected. Two isotopes are currently known, Uup-287 and Uup-288, with 288Uup having the longer half-life of ~100 ms, although two new heavier isotopes have recently been discovered which probably have even longer half-lives.

Contents

History

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Discovery profile

On February 2, 2004, synthesis of ununpentium was reported in Physical Review C by a team composed of Russian scientists at the Joint Institute for Nuclear Research in Dubna, and American scientists at the Lawrence Livermore National Laboratory.[2][3] The team reported that they bombarded americium-243 with calcium-48 ions to produce four atoms of ununpentium. These atoms, they report, decayed by emission of alpha-particles to ununtrium in approximately 100 milliseconds.

4820Ca + 24395Am291115Uup*288115Uup

The Dubna-Livermore collaboration has strengthened their claim for the discovery of ununpentium by conducting chemical experiments on the decay daughter 268Db. In experiments in June 2004 and December 2005, the Dubnium isotope was successfully identified by milking the Db fraction and measuring any SF activities.[4][5] Both the half-life and decay mode were confirmed for the proposed 268Db which lends support to the assignment of Z=115 to the parent nuclei.

Official claim of discovery of element 115

Sergei Dmitriev from the Flerov laboratory of nuclear reactions (FLNR) in Dubna, Russia, has formally put forward their claim of discovery of element 115 to the Joint Working Party (JWP) from IUPAC and IUPAP.[6] The JWP are expected to publish their opinions on such claims in the near future.[citation needed]

Naming

Ununpentium is historically known as eka-bismuth. Ununpentium is a temporary IUPAC systematic element name. Research scientists usually refer to the element simply as element 115.

Future experiments

As a primary next-goal for the Dubna team, they are planning to examine two products of the 243Am + 48Ca using mass spectrometry in their state-of-the-art MASHA machine. They will attempt to isolate the dubnium products, convert them chemically into a volatile compound, most likely 268DbCl5, and measure the mass directly.

The FLNR also have future plans to study light isotopes of element 115 using the reaction 241Am + 48Ca.[7]

Isotopes and nuclear properties

Nucleosynthesis

Target-projectile combinations leading to Z=115 compound nuclei

The below table contains various combinations of targets and projectiles which could be used to form compound nuclei with Z=115.

Target Projectile CN Attempt result
208Pb 75As 283115 Reaction yet to be attempted
232Th 55Mn 287115 Reaction yet to be attempted
238U 51V 289115 Failure to date
237Np 50Ti 287115 Reaction yet to be attempted
244Pu 45Sc 289115 Reaction yet to be attempted
243Am 48Ca 291115 Successful reaction
241Am 48Ca 289115 Reaction yet to be attempted
248Cm 41K 289115 Reaction yet to be attempted
249Bk 40Ar 289115 Reaction yet to be attempted
249Cf 37Cl 286115 Reaction yet to be attempted

Hot fusion

This section deals with the synthesis of nuclei of ununpentium by so-called "hot" fusion reactions. These are processes which create compound nuclei at high excitation energy (~40-50 MeV, hence "hot"), leading to a reduced probability of survival from fission. The excited nucleus then decays to the ground state via the emission of 3-5 neutrons. Fusion reactions utilizing 48Ca nuclei usually produce compound nuclei with intermediate excitation energies (~30-35 MeV) and are sometimes referred to as "warm" fusion reactions. This leads, in part, to relatively high yields from these reactions.

238U(51V,xn)289−xUup

There are strong indications that this reaction was performed in late 2004 as part of a uranium(IV) fluoride target test at the GSI. No reports have been published suggesting that no products atoms were detected, as anticipated by the team.[8]

243Am(48Ca,xn)291−xUup (x=3,4)

This reaction was first performed by the team in Dubna in July-August 2003. In two separate runs they were able to detect 3 atoms of 288Uup and a single atom of 287Uup. The reaction was studied further in June 2004 in an attempt to isolate the descendant 268Db from the 288Uup decay chain. After chemical separation of a +4/+5 fraction, 15 SF decays were measured with a lifetime consistent with 268Db. In order to prove that the decays were from dubnium-268, the team repeated the reaction in August 2005 and separated the +4 and +5 fractions and further separated the +5 fractions into tantalum-like and niobium-like ones. Five SF activities were observed, all occurring in the +5 fractions and none in the tantalum-like fractions, proving that the product was indeed isotopes of dubnium.

Chronology of isotope discovery

Isotope Year discovered Discovery reaction
287Uup 2003 243Am(48Ca,4n)
288Uup 2003 243Am(48Ca,3n)
289Uup 2009 249Bk(48Ca,4n)
290Uup 2009 249Bk(48Ca,3n)

Yields of isotopes

Hot fusion

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

Projectile Target CN 2n 3n 4n 5n
48Ca 243Am 291Uup 3.7 pb, 39.0 MeV 0.9 pb, 44.4 MeV

Theoretical calculations

Decay characteristics

Theoretical calculations using a quantum-tunneling model support the experimental alpha-decay half-lives.[9]

Evaporation residue cross sections

The below table contains various targets-projectile combinations for which calculations have provided estimates for cross section yields from various neutron evaporation channels. The channel with the highest expected yield is given.

MD = multi-dimensional; DNS = Di-nuclear system; σ = cross section

Target Projectile CN Channel (product) σmax Model Ref
243Am 48Ca 291115 3n (288115) 3 pb MD [10]
243Am 48Ca 291115 4n (287115) 2 pb MD [10]
243Am 48Ca 291115 3n (288115) 1 pb DNS [11]
242Am 48Ca 290115 3n (287115) 2.5 pb DNS [11]

Chemical properties

Extrapolated chemical properties

Oxidation states

Element 115 is projected to be the third member of the 7p series of non-metals and the heaviest member of group 15 (VA) in the Periodic Table, below bismuth. In this group, each member is known to portray the group oxidation state of +V but with differing stability. For nitrogen, the +V state is very difficult to achieve due to the lack of low-lying d-orbitals and the inability of the small nitrogen atom to accommodate five ligands. The +V state is well represented for phosphorus, arsenic, and antimony. However, for bismuth it is rare due to the reluctance of the 6s2 electron to participate in bonding. This effect is known as the "inert pair effect" and is commonly linked to relativistic stabilisation of the 6s-orbitals. It is expected that element 115 will continue this trend and portray only +III and +I oxidation states. Nitrogen(I) and bismuth(I) are known but rare and Uup(I) is likely to show some unique properties.[12]

Chemistry

It is expected that the chemistry of ununpentium will be related to its lighter homologue bismuth. In this regard it is expected to undergo oxidation only as far as the trioxide Uup2O3. Oxidation with the more reactive halogens should form the trihalides, such as UupF3 and UupCl3. The less-oxidising, heavier halogens, may well only be able to promote the formation of the monohalides, UupBr and UupI.

See also

References

  1. ^ J. Chatt (1979). "Recommendations for the Naming of Elements of Atomic Numbers Greater than 100". Pure Appl. Chem. 51: 381–384. doi:10.1351/pac197951020381. 
  2. ^ Oganessian, Yu. Ts. (2004). "Experiments on the synthesis of element 115 in the reaction 243Am(48Ca,xn)291?x115". Physical Review C 69: 021601. doi:10.1103/PhysRevC.69.021601. 
  3. ^ Oganessian et al. (2003). "Experiments on the synthesis of element 115 in the reaction 243Am(48Ca,xn)291−x115""]. JINR preprints. http://www.jinr.ru/publish/Preprints/2003/178(E7-2003-178).pdf. 
  4. ^ Oganessian et al. (2004). "Results of the experiment on chemical identification of db as a decay product of element 115". JINR preprints. http://www.jinr.ru/publish/Preprints/2004/157(e12-2004-157).pdf. 
  5. ^ Oganessian, Yu. Ts. (2005). "Synthesis of elements 115 and 113 in the reaction ^{243}Am+^{48}Ca". Physical Review C 72: 034611. doi:10.1103/PhysRevC.72.034611. 
  6. ^ "Project: Priority claims for the discovery of elements with atomic number greater than 111". IUPAC. http://www.iupac.org/web/ins/2006-046-1-200. Retrieved 2009-07-07. 
  7. ^ "Study of heavy and superheavy nuclei (see experiment 1.5)". http://flerovlab.jinr.ru/flnr/education_list.html. 
  8. ^ "List of experiments 2000-2006". http://opal.dnp.fmph.uniba.sk/~beer/experiments.php. 
  9. ^ C. Samanta, P. Roy Chowdhury and D.N. Basu (2007). "Predictions of alpha decay half lives of heavy and superheavy elements". Nucl. Phys. A 789: 142–154. doi:10.1016/j.nuclphysa.2007.04.001. 
  10. ^ a b Zagrebaev, V (2004). "Fusion-fission dynamics of super-heavy element formation and decay". Nuclear Physics A 734: 164. doi:10.1016/j.nuclphysa.2004.01.025. http://nrv.jinr.ru/pdf_file/npa_04.pdf. 
  11. ^ a b Feng, Z (2009). "Production of heavy and superheavy nuclei in massive fusion reactions". Nuclear Physics A 816: 33. doi:10.1016/j.nuclphysa.2008.11.003. http://arxiv.org/pdf/0803.1117. 
  12. ^ Keller, O. L., Jr.; C. W. Nestor, Jr. (1974). "Predicted properties of the superheavy elements. III. Element 115, Eka-bismuth". Journal of Physical Chemistry 78: 1945. doi:10.1021/j100612a015. 

External links


Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

See also ununpentium

German

Chemical Element: Uup (atomic number 115)

Noun

Ununpentium n

  1. ununpentium

Simple English

Ununpentium is a chemical element. It is also named eka-bismuth. It has the symbol Uup. It has the atomic number 115. It is a superheavy element.

Ununpentium does not exist in nature. It is a synthetic element, made from a fusion reaction between americium and calcium.

Ununpentium is in the center of the theoretical island of stability. No stable isotopes of ununpentium have yet been found. Models predict that the stable isotope of ununpentium should have 184 neutrons. The stable isotope with 184 neutrons is 299Uup. The isotope that has been made has only 173 neutrons (288Uup).

Contents

History

On February 2 2004 a report that ununpentium and ununtrium were made was written in a journal named Physical Review C. The report was written by a team of Russian scientists at Dubna University's Joint Institute for Nuclear Research and American scientists at the Lawrence Livermore National Laboratory.[1],[2]

These people reported that they bombarded a different chemical element named americium with the element calcium to make four atoms of ununpentium.

Scientists of Japan also report that they have made Ununpentium.

In May 2006 at the Joint Institute for Nuclear Research this element was made by another method and what the final products from radioactive decay were was found by chemical analysis.

Name

Ununpentium is a temporary IUPAC systematic element name.

Chemical properties

Not enough ununpentium has been made to measure its physical or chemical properties. It is thought that it would be a hard metal. It may have a low melting point of about 250 °C. It may be slightly colored.

Ununpentium is in the same group as bismuth but its chemical properties will be different. The chemistry of ununpentium will be very influenced by special relativity. It will make its properties different to the other elements in the periodic table that have a smaller atomic number.[3] One important difference from bismuth is the presence of a stable oxidation state of +I (Uup+). The (Uup+) ion is thought to have chemical properties like Tl+.

In popular culture

Ununpentium is inside the island of stability. This is likely to be why it is found in popular culture. It is more likely to be talked about in UFO conspiracy theories.

The most popular story about ununpentium is from Bob Lazar . It is not pseudoscience because it is a refutable theory, however Lazar's claims are not backed by any direct experimental evidence at this time. [4]

References

  1. Oganessian, Yu. Ts.; et al. (2004). "Experiments on the synthesis of element 115 in the reaction 243Am(48Ca,xn)291−x115". Physical Review C 69: 021601. doi:10.1103/PhysRevC.69.021601. http://link.aps.org/abstract/PRC/v69/e021601. 
  2. Oganessian, Yu. Ts.; et al. (2005). "Synthesis of elements 115 and 113 in the reaction 243Am + 48Ca". Physical Review C 72: 034611. doi:10.1103/PhysRevC.72.034611. http://link.aps.org/abstract/PRC/v72/e034611. 
  3. Keller, O. L., Jr.; C. W. Nestor, Jr. (1974). [Expression error: Unexpected < operator "Predicted properties of the superheavy elements. III. Element 115, Eka-bismuth"]. Journal of Physical Chemistry 78: 1945. doi:10.1021/j100612a015. 
  4. Lazar Critique, D. L. Morgan.

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