Unbibium
Encyclopedia
Unbibium also referred to as eka
-thorium
or element 122, is the temporary name of a currently unknown chemical element
in the periodic table
that has the temporary symbol Ubb and the atomic number 122.
In 2008, it was claimed to have been discovered in natural thorium samples but that claim has now been dismissed by recent repetitions of the experiment using more accurate techniques.
or thorium
. It would most likely form the dioxide, UbbO
2, and trihalides, such as UbbF
3 and UbbCl
3. The predicted oxidation states are III and IV (and perhaps II).
No atoms were detected and a yield limit of 5 mb
(5,000,000 pb
) was measured. Current results (see ununquadium
) have shown that the sensitivity of this experiment was too low by at least 6 orders of magnitude.
In 2000, the Gesellschaft für Schwerionenforschung
performed a very similar experiment with much higher sensitivity:
These results indicate that the synthesis of such heavier elements remains a significant challenge and further improvements of beam intensity and experimental efficiency is required. The sensitivity should be increased to 1 fb
.
claimed to have found single atoms of unbibium in naturally occurring thorium
deposits at an abundance of between 10−11 and 10−12, relative to thorium.
The claim of Marinov et al. was criticized by a part of the scientific community, and Marinov says he has submitted the article to the journals Nature
and Nature Physics
but both turned it down without sending it for peer review.
A criticism of the technique, previously used in purportedly identifying lighter thorium
isotopes by mass spectrometry,
was published in Physical Review C in 2008. A rebuttal by the Marinov group was published in Physical Review C after the published comment.
A repeat of the thorium-experiment using the superior method of Accelerator Mass Spectrometry (AMS) failed to confirm the results, despite a 100-fold better sensitivity. This result throws considerable doubt on the results of the Marinov collaboration with regards to their claims of long-lived isotopes of thorium
, roentgenium
and unbibium.
Mendeleev's predicted elements
Professor Dmitri Mendeleev published the first Periodic Table of the Atomic Elements in 1869 based on properties which appeared with some regularity as he laid out the elements from lightest to heaviest....
-thorium
Thorium
Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....
or element 122, is the temporary name of a currently unknown chemical element
Chemical element
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...
in the periodic table
Periodic table
The periodic table of the chemical elements is a tabular display of the 118 known chemical elements organized by selected properties of their atomic structures. Elements are presented by increasing atomic number, the number of protons in an atom's atomic nucleus...
that has the temporary symbol Ubb and the atomic number 122.
In 2008, it was claimed to have been discovered in natural thorium samples but that claim has now been dismissed by recent repetitions of the experiment using more accurate techniques.
Extrapolated reactivity
If group reactivity is followed, unbibium should be a reactive metal, more reactive than ceriumCerium
Cerium is a chemical element with the symbol Ce and atomic number 58. It is a soft, silvery, ductile metal which easily oxidizes in air. Cerium was named after the dwarf planet . Cerium is the most abundant of the rare earth elements, making up about 0.0046% of the Earth's crust by weight...
or thorium
Thorium
Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....
. It would most likely form the dioxide, UbbO
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
2, and trihalides, such as UbbF
Fluorine
Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...
3 and UbbCl
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
3. The predicted oxidation states are III and IV (and perhaps II).
Neutron evaporation
The first attempt to synthesize unbibium was performed in 1972 by Flerov et al. at JINR, using the hot fusion reaction:No atoms were detected and a yield limit of 5 mb
Barn (unit)
A barn is a unit of area. Originally used in nuclear physics for expressing the cross sectional area of nuclei and nuclear reactions, today it is used in all fields of high energy physics to express the cross sections of any scattering process, and is best understood as a measure of the...
(5,000,000 pb
Barn (unit)
A barn is a unit of area. Originally used in nuclear physics for expressing the cross sectional area of nuclei and nuclear reactions, today it is used in all fields of high energy physics to express the cross sections of any scattering process, and is best understood as a measure of the...
) was measured. Current results (see ununquadium
Ununquadium
Ununquadium is the temporary name of a radioactive chemical element with the temporary symbol Uuq and atomic number 114. There is no proposed name yet, although flerovium has been discussed in the media.About 80 decays of atoms of...
) have shown that the sensitivity of this experiment was too low by at least 6 orders of magnitude.
In 2000, the Gesellschaft für Schwerionenforschung
Gesellschaft für Schwerionenforschung
The GSI Helmholtz Centre for Heavy Ion Research GmbH in the Wixhausen suburb of Darmstadt, Germany is a federally and state co-funded heavy ion research center. The current director of GSI is Horst Stöcker who succeeded Walter F...
performed a very similar experiment with much higher sensitivity:
These results indicate that the synthesis of such heavier elements remains a significant challenge and further improvements of beam intensity and experimental efficiency is required. The sensitivity should be increased to 1 fb
Barn (unit)
A barn is a unit of area. Originally used in nuclear physics for expressing the cross sectional area of nuclei and nuclear reactions, today it is used in all fields of high energy physics to express the cross sections of any scattering process, and is best understood as a measure of the...
.
Compound nucleus fission
Several experiments have been performed between 2000-2004 at the Flerov laboratory of Nuclear Reactions studying the fission characteristics of the compound nucleus 306Ubb. Two nuclear reactions have been used, namely 248Cm+58Fe and 242Pu+64Ni. The results have revealed how nuclei such as this fission predominantly by expelling closed shell nuclei such as 132Sn (Z=50, N=82). It was also found that the yield for the fusion-fission pathway was similar between 48Ca and 58Fe projectiles, indicating a possible future use of 58Fe projectiles in superheavy element formation.Target-projectile combinations leading to Z=122 compound nuclei
The table below contains various combinations of targets and projectiles which could be used to form compound nuclei with atomic number 122.| Target | Projectile | CN | Attempt result |
|---|---|---|---|
| 208Pb | 94Zr | 302Ubb | |
| 232Th | 74Ge | 306Ubb | |
| 238U | 70Zn | 308Ubb | |
| 238U | 66Zn | 304Ubb | |
| 244Pu | 64Ni | 308Ubb | |
| 248Cm | 58Fe | 306Ubb | |
| 249Cf | 54Cr | 303Ubb | |
| 259No | 48Ca | 307Ubb |
Claimed discovery as a naturally occurring element
On April 24, 2008, a group led by Amnon Marinov at the Hebrew University of JerusalemHebrew University of Jerusalem
The Hebrew University of Jerusalem ; ; abbreviated HUJI) is Israel's second-oldest university, after the Technion – Israel Institute of Technology. The Hebrew University has three campuses in Jerusalem and one in Rehovot. The world's largest Jewish studies library is located on its Edmond J...
claimed to have found single atoms of unbibium in naturally occurring thorium
Thorium
Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....
deposits at an abundance of between 10−11 and 10−12, relative to thorium.
The claim of Marinov et al. was criticized by a part of the scientific community, and Marinov says he has submitted the article to the journals Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
and Nature Physics
Nature Physics
Nature Physics, is a monthly, peer reviewed, scientific journal published by the Nature Publishing Group. It was first published in October 2005 . The Chief Editor is Alison Wright, who is a full-time professional editor employed by this journal...
but both turned it down without sending it for peer review.
A criticism of the technique, previously used in purportedly identifying lighter thorium
Thorium
Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....
isotopes by mass spectrometry,
was published in Physical Review C in 2008. A rebuttal by the Marinov group was published in Physical Review C after the published comment.
A repeat of the thorium-experiment using the superior method of Accelerator Mass Spectrometry (AMS) failed to confirm the results, despite a 100-fold better sensitivity. This result throws considerable doubt on the results of the Marinov collaboration with regards to their claims of long-lived isotopes of thorium
Thorium
Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....
, roentgenium
Roentgenium
Roentgenium is a synthetic radioactive chemical element with the symbol Rg and atomic number 111. It is placed as the heaviest member of the group 11 elements, although a sufficiently stable isotope has not yet been produced in a sufficient amount that would confirm this position as a heavier...
and unbibium.