Unbibium

Unbibium (/[invalid input: 'icon']uːnˈbɪbiəm/), 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.

Unbibium, ₁₂₂Ubb

Theoretical element
Unbibium
Pronunciation	/ˌuːnbaɪˈbaɪəm/ ​(OON-by-BY-əm)
Alternative names	element 122, eka-thorium
Unbibium in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Ununennium Unbinilium Unquadtrium Unquadquadium Unquadpentium Unquadhexium Unquadseptium Unquadoctium Unquadennium Unpentnilium Unpentunium Unpentbium Unpenttrium Unpentquadium Unpentpentium Unpenthexium Unpentseptium Unpentoctium Unpentennium Unhexnilium Unhexunium Unhexbium Unhextrium Unhexquadium Unhexpentium Unhexhexium Unhexseptium Unhexoctium Unhexennium Unseptnilium Unseptunium Unseptbium Unbiunium Unbibium Unbitrium Unbiquadium Unbipentium Unbihexium Unbiseptium Unbioctium Unbiennium Untrinilium Untriunium Untribium Untritrium Untriquadium Untripentium Untrihexium Untriseptium Untrioctium Untriennium Unquadnilium Unquadunium Unquadbium — ↑ Ubb ↓ — unbiunium ← unbibium → unbitrium
Atomic number (Z)	122
Group	g-block groups (no number)
Period	period 8 (theoretical, extended table)
Block	g-block
Electron configuration	predictions vary, see text
Physical properties
Phase at STP	unknown
Atomic properties
Oxidation states	common: (none) (+4)[1]
Ionization energies	1st: 545 (predicted)[2] kJ/mol 2nd: 1090 (predicted)[2] kJ/mol 3rd: 1848 (predicted) kJ/mol
Other properties
CAS Number	54576-73-7
History
Naming	IUPAC systematic element name
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In 2008, it was claimed to have been discovered in natural thorium samples^[3] but that claim has now been dismissed by recent repetitions of the experiment using more accurate techniques.

History

Neutron evaporation

The first attempt to synthesize unbibium was performed in 1972 by Flerov et al. at JINR, using the hot fusion reaction:

${\displaystyle \,_{92}^{238}\mathrm {U} +\,_{30}^{66}\mathrm {Zn} \to \,_{122}^{304}\mathrm {Ubb} ^{*}\to \ {\mbox{no atoms}}.}$

No atoms were detected and a yield limit of 5 mb (5,000,000 pb)^{[dubious – discuss]} was measured. Current results (see flerovium) have shown that the sensitivity of this experiment was too low by at least 6 orders of magnitude.^{[അവലംബം ആവശ്യമാണ്]}

In 2000, the Gesellschaft für Schwerionenforschung performed a very similar experiment with much higher sensitivity:

${\displaystyle \,_{92}^{238}\mathrm {U} +\,_{30}^{70}\mathrm {Zn} \to \,_{122}^{308}\mathrm {Ubb} ^{*}\to \ {\mbox{no atoms}}.}$

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.^{[അവലംബം ആവശ്യമാണ്]}

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.^[4]

Claimed discovery as a naturally occurring element

On April 24, 2008, a group led by Amnon Marinov at the Hebrew University of Jerusalem 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.^[3] 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.^[5]

A criticism of the technique, previously used in purportedly identifying lighter thorium isotopes by mass spectrometry,^[6][7] was published in Physical Review C in 2008.^[8] A rebuttal by the Marinov group was published in Physical Review C after the published comment.^[9]

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.^[10] This result throws considerable doubt on the results of the Marinov collaboration with regards to their claims of long-lived isotopes of thorium,^[6][7] roentgenium^[11] and unbibium.^[3]

Nucleosynthesis

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.^{[അവലംബം ആവശ്യമാണ്]}

Target	Projectile	CN	Attempt result
238U	70Zn	308Ubb	Failure to date
238U	66Zn	304Ubb	Failure to date
242Pu	64Ni	306Ubb	Failure to date
248Cm	58Fe	306Ubb	Failure to date

Chemical properties

Electronic structure

It has been predicted by Ephraim Eliav et al. that unbibium will have the electron configuration [Uuo]8s²7d¹8p¹.^[12]

Extrapolated chemical properties

Chemistry

If group reactivity is followed, unbibium should be a reactive metal, more reactive than cerium or thorium. Unbibium would most likely form the dioxide, UbbO₂, and trihalides, such as UbbF₃ and UbbCl₃. The predicted oxidation states are III and IV (and perhaps II).^{[അവലംബം ആവശ്യമാണ്]}

See also

• Island of stability
• Systematic element name
• unbiunium–unbitrium