Ununtrium

"Uut" redirects here. For other uses, see Uut (disambiguation).

copernicium ← ununtrium → ununquadium Tl ↑ Uut ↓ (Uht) 113Uut Periodic table
Appearance
Unknown
General properties
Name, symbol, number	ununtrium, Uut, 113
Pronunciation	i/uːnˈuːntriəm/ oon-OON-tree-əm
Category notes	presumably other metals
Group, period, block	13, 7, p
Standard atomic weight	[286]
Electron configuration	[Rn] 5f14 6d10 7s2 7p1 (predicted)
Electrons per shell	2, 8, 18, 32, 32, 18, 3 (predicted) (Image)
Physical properties
Atomic properties
Miscellanea
CAS registry number	54084-70-7
Most stable isotopes
Main article: Isotopes of ununtrium
iso NA half-life DM DE (MeV) DP 286Uut syn 19.6 s α 9.63 282Rg 285Uut syn 5.5 s α 9.74,9.48 281Rg 284Uut syn 0.49 s α 10.00 280Rg 283Uut syn 0.10 s α 10.12 279Rg 282Uut syn 73 ms α 10.63 278Rg 278Uut syn 0.34 ms α 11.68 274Rg

Ununtrium is the temporary name of a synthetic element with the temporary symbol Uut and atomic number 113.

It is placed as the heaviest member of the group 13 (IIIA) elements although a sufficiently stable isotope is not known at this time that would allow chemical experiments to confirm its position as a heavier homologue to thallium. It was first detected in 2003 in the decay of ununpentium and was synthesized directly in 2004. Only fourteen atoms of ununtrium have been observed to date. The longest-lived isotope known is ²⁸⁶Uut with a half-life of ~20 s, allowing first chemical experiments to study its chemistry.

History

Discovery profile

The first report of ununtrium was in August 2003 when it was identified as a decay product of ununpentium. These results were published on February 1, 2004, by a team composed of Russian scientists at Dubna (Joint Institute for Nuclear Research), and American scientists at the Lawrence Livermore National Laboratory.

$\,^{48}_{20}\mathrm{Ca} + \,^{243}_{95}\mathrm{Am} \to \,^{288,287}\mathrm{Uup} \to \,^{284,283}\mathrm{Uut} \to\$

On July 23, 2004, a team of Japanese scientists at RIKEN detected a single atom of ²⁷⁸Uut using the cold fusion reaction between bismuth-209 and zinc-70. They published their results on September 28, 2004.

$\,^{70}_{30}\mathrm{Zn} + \,^{209}_{83}\mathrm{Bi} \to \,^{279}_{113}\mathrm{Uut} ^{*} \to \,^{278}_{113}\mathrm{Uut} + \,^{1}_{0}\mathrm{n}$

Support for their claim appeared in 2004 when scientists at the Institute of Modern Physics (IMP) identified ²⁶⁶Bh as decaying with identical properties to their single event (see bohrium).

The RIKEN team produced a further atom on April 2, 2005, although the decay data were different from the first chain, and may be due to the formation of a meta-stable isomer.

The Dubna-Livermore collaboration has strengthened their claim for the discovery of ununtrium 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. Both the half-life and decay mode were confirmed for the proposed ²⁶⁸Db which lends support to the assignment of Z=115 and Z=113 to the parent and daughter nuclei.

Theoretical estimates of alpha-decay half-lives of alpha-decay chains from element 113 are in good agreement with the experimental data.

Recent experiments at Dubna have fully confirmed the data for ununpentium and ununtrium but have yet to be fully published and reviewed by the JWP. This process is likely not to occur for some time.^{[citation needed]}

Naming

The element with atomic number 113 is historically known as eka-thallium. Ununtrium (Uut) is a temporary IUPAC systematic element name. Research scientists usually refer to the element simply as element 113 (or E113).

Proposed names by claimants

Claims to the discovery of ununtrium have been put forward by Dmitriev of the Dubna team and Morita of the RIKEN team. The IUPAC/IUPAP Joint Working Party will decide to whom the right to suggest a name will be given. In 2011, the IUPAC has evaluated the 2004 RIKEN experiments and 2004 and 2007 Dubna experiments, and concluded that they did not meet the criteria for discovery.

The following names have been suggested by the above-mentioned teams claiming discovery:

Group	Proposed Name	Derivation
RIKEN	Japonium	Japan: country of group claimants
	Rikenium	RIKEN: institute of group claimants
Dubna team	Becquerelium	Henri Becquerel, French physicist

Nucleosynthesis

Target-projectile combinations leading to Z=113 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 an atomic number of 113.

Target	Projectile	CN	Attempt result
208Pb	71Ga	279Uut	Reaction yet to be attempted
209Bi	70Zn	279Uut	Successful reaction
232Th	51V	283Uut	Reaction yet to be attempted
238U	45Sc	283Uut	Reaction yet to be attempted
237Np	48Ca	285Uut	Successful reaction
244Pu	41K	285Uut	Reaction yet to be attempted
243Am	40Ar	283Uut	Reaction yet to be attempted
248Cm	37Cl	285Uut	Reaction yet to be attempted
249Bk	36S	285Uut	Reaction yet to be attempted
249Cf	31P	280Uut	Reaction yet to be attempted

Cold fusion

This section deals with the synthesis of nuclei of ununtrium 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(⁷⁰Zn,xn)^279-xUut (x=1)

The synthesis of ununtrium was first attempted in 1998 by the team at GSI using the above cold fusion reaction. In two separate runs, they were unable to detect any atoms and calculated a cross section limit of 900 fb. They repeated the experiment in 2003 and lowered the limit further to 400 fb. In late 2003, the emerging team at RIKEN using their efficient apparatus GARIS attempted the reaction and reached a limit of 140 fb. In December 2003 – August 2004, they resorted to 'brute force' and performed an eight-month-long irradiation in which they increased the sensitivity to 51 fb. They were able to detect a single atom of ²⁷⁸Uut. They repeated the reaction in several runs in 2005 and were able to synthesize a second atom. They calculated a record-low 31 fb for the cross section for the 2 atoms. The reaction was repeated again in 2006 with two long production runs but no further atoms were detected. This lowered the yield further to the current value of just 23 fb.

Hot fusion

This section deals with the synthesis of nuclei of ununtrium 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.

²³⁷Np(⁴⁸Ca,xn)^285-xUut (x=3)

In June 2006, the Dubna-Livermore team synthesised ununtrium directly in the "warm" fusion reaction between neptunium-237 and calcium-48 nuclei. Two atoms of ²⁸²Uut were detected with a cross section of 900 fb.

As decay product

Ununtrium has also been detected in the decay of ununpentium and ununseptium.

Yields of isotopes

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

Projectile	Target	CN	1n	2n	3n
70Zn	209Bi	279Uut	23 fb

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

Projectile	Target	CN	3n	4n	5n
48Ca	237Np	285Uut	0.9 pb, 39.1 MeV

Theoretical calculations

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.

DNS = Di-nuclear system; σ = cross section

Target	Projectile	CN	Channel (product)	σmax	Model	Ref
209Bi	70Zn	279Uut	1n (278113)	30 fb	DNS
237Np	48Ca	285Uut	3n (282113)	0.4 pb	DNS

Isotopes and nuclear properties

Chronology of isotope discovery

Isotope	Year discovered	Discovery reaction
278Uut	2004	209Bi(70Zn,n)
279Uut	unknown
280Uut	unknown
281Uut	unknown
282Uut	2006	237Np(48Ca,3n)
283Uut	2003	243Am(48Ca,4n)
284Uut	2003	243Am(48Ca,3n)
285Uut	2009	249Bk(48Ca,4n)
286Uut	2009	249Bk(48Ca,3n)

Chemical properties

Extrapolated chemical properties

Oxidation states

Ununtrium is projected to be the first member of the 7p series of elements and the heaviest member of group 13 (IIIA) in the Periodic Table, below thallium. Each of the members of this group show the group oxidation state of +III. However, thallium has a tendency to form only a stable +I state due to the "inert pair effect", explained by the relativistic stabilisation of the 7s-orbitals, resulting in a higher ionisation potential and weaker tendency to participate in bonding.

Chemistry

Ununtrium should portray eka-thallium chemical properties and should therefore form a monoxide, Uut₂O, and monohalides, UutF, UutCl, UutBr, and UutI. If the +III state is accessible, it is likely that it is only possible in the oxide, Uut₂O₃, and fluoride, UutF₃. Spin-orbit splitting of the 7p orbitals may stabilize the −1 state as well, as is seen with gold(−1) (aurides).

See also

• Isotopes of ununtrium
• Island of stability

External links

• WebElements.com: Ununtrium
• Uut and Uup Add Their Atomic Mass to Periodic Table
• Apsidium: Ununtrium 113 Uut
• Discovery of Elements 113 and 115
• Superheavy elements