Ununpentium

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ununquadium ← ununpentium → ununhexium Bi ↑ Uup ↓ (Uhp) 115Uup Periodic table
Appearance
unknown
General properties
Name, symbol, number	ununpentium, Uup, 115
Group, period, block	15, 7, 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 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.

	Ununpentium Common English pronunciation of ununpentium
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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.

Contents 1 History 1.1 Discovery profile 1.1.1 Official claim of discovery of element 115 1.2 Naming 1.3 Future experiments 2 Isotopes and nuclear properties 2.1 Nucleosynthesis 2.1.1 Target-projectile combinations leading to Z=115 compound nuclei 2.1.2 Hot fusion 2.1.2.1 238U(51V,xn)289−xUup 2.1.2.2 243Am(48Ca,xn)291−xUup (x=3,4) 2.1.3 Chronology of isotope discovery 2.2 Yields of isotopes 2.2.1 Hot fusion 2.3 Theoretical calculations 2.3.1 Decay characteristics 2.3.2 Evaporation residue cross sections 3 Chemical properties 3.1 Extrapolated chemical properties 3.1.1 Oxidation states 3.1.2 Chemistry 4 See also 5 References 6 External links

[edit] History

[edit] 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 + 24395Am → 291115Uup^* → 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.

[edit] 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]}

[edit] 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.

[edit] 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]

[edit] Isotopes and nuclear properties

[edit] Nucleosynthesis

[edit] 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 combinations leading to Z=115 nuclei

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

[edit] 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.

[edit] 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]

[edit] 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.

[edit] Chronology of isotope discovery

Isotope	Year discovered	Discovery reaction
287Uup	2003	243Am(48Ca,4n)
288Uup	2003	243Am(48Ca,3n)

[edit] Yields of isotopes

[edit] 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

[edit] Theoretical calculations

[edit] Decay characteristics

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

[edit] 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]

[edit] Chemical properties

[edit] Extrapolated chemical properties

[edit] 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]

[edit] 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.

[edit] See also

• Island of stability
• Elerium-115

[edit] References

[edit] External links

• Uut and Uup Add Their Atomic Mass to Periodic Table
• Superheavy elements
• History and etymology

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