Ununtrium

copernicium ← ununtrium → ununquadium

Tl
↑
Uut
↓
(Uht)

113Uut

Periodic table

Appearance

Unknown

General properties

Name, symbol, number

ununtrium, Uut, 113

Pronunciation

ⁱ /uːnˈuːntri.əm/
oon-OON-tree-əm

Category notes

presumably other metals

Group, period, block

13, 7, p

Standard atomic weight

[286]g·mol⁻¹

Electron configuration

perhaps [Rn] 5f¹⁴ 6d¹⁰ 7s² 7p¹
(guess based on thallium)

Electrons per shell

2, 8, 18, 32, 32, 18, 3 (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
²⁸⁷Uut	syn	20 m	unknown	unknown	^unknownunknown
²⁸⁶Uut	syn	19.6 s	α	9.63	²⁸²Rg
²⁸⁵Uut	syn	~4.6 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 (pronounced /uːnˈuːntri.əm/ ( listen)^[1] oon-OON-tree-əm) 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. 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.^[2]^[3]

$\,^{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.^[4]

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

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 was 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 Jun 2004 and Dec 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.^[5]^[6]

Theoretical estimates of alpha-decay half-lives of alpha-decay chains from element 113 are in good agreement with the experimental data.^[7]

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. The IUPAC have the final say on the official adoption of a name. The table below gives the names that the teams above have suggested and which can be verified by press interviews.

Group	Proposed Name	Derivation
RIKEN	Japonium^[8]	Japan: country of group claimants
RIKEN	Rikenium^[8]	RIKEN: institute of group claimants

Isotopes and nuclear properties

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.^[9] They repeated the experiment in 2003 and lowered the limit further to 400 fb.^[9] 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.^[4] 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.^[10]

As a decay product

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

Chronology of isotope discovery

Isotope	Year discovered	Discovery reaction
²⁷⁸Uut	2004	²⁰⁹Bi(⁷⁰Zn,n) ^[4]
²⁷⁹Uut	unknown
²⁸⁰Uut	unknown
²⁸¹Uut	unknown
²⁸²Uut	2006	²³⁷Np(⁴⁸Ca,3n)^[10]
²⁸³Uut	2003	²⁴³Am(⁴⁸Ca,4n)^[2]
²⁸⁴Uut	2003	²⁴³Am(⁴⁸Ca,3n)^[2]
²⁸⁵Uut	2009	²⁴⁹Bk(⁴⁸Ca,4n)
²⁸⁶Uut	2009	²⁴⁹Bk(⁴⁸Ca,3n)

Yields of isotopes

Cold fusion

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

Hot fusion

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 ^[10]

Theoretical calculations

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.

DNS = Di-nuclear system; σ = cross section

Target	Projectile	CN	Channel (product)	σ_max	Model	Ref
²⁰⁹Bi	⁷⁰Zn	²⁷⁹Uut	1n (²⁷⁸113)	30 fb	DNS	^[11]
²³⁷Np	⁴⁸Ca	²⁸⁵Uut	3n (²⁸²113)	0.4 pb	DNS	^[12]

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.