Unbiunium

unbinilium ← unbiunium → unbibium - ↑ Ubu ↓ Usu 121Ubu Periodic table
Appearance
General properties
Name, symbol, number	unbiunium, Ubu, 121
Pronunciation	/uːnbaɪˈuːniəm/
Element category	superactinides
Group, period, block	n/a, 8, g
Standard atomic weight	unknown
Electron configuration	[Uuo] 5g1 8s2 (predicted)
Electrons per shell	2, 8, 18, 32, 33, 18, 8, 2 (predicted) (Image)
Physical properties
Atomic properties
Oxidation states	3 (predicted)

Unbiunium ( /uːnbaɪˈuːniəm/), also known as eka-actinium or element 121, is the temporary name of a hypothetical chemical element in the periodic table that has the temporary symbol Ubu and has the atomic number 121. It would be the first element in the g-block of the periodic table. As of August 2011, no attempt has been made to synthesize unbiunium.

Naming

The name unbiunium is a systematic element name, used as a placeholder until it is confirmed by other research groups and the IUPAC decides on a name. Usually, the name suggested by the discoverer(s) is chosen.

Electronic configurations

Unbiunium is the first element whose ground state electron configuration may contain an electron in a g subshell, which would make it the first element in the g-block. However, neither lanthanum nor actinium show such a predicted ground state for the f-block, and lie in the transition metals, so unbiunium's third electron should also hang up. Other elements have access to their g subshells, though not in their ground states. Computations have indicated that the ground state of the element would be 8s²8p¹.

Isotopes

Calculations have shown that ³²⁰Ubu would be the most stable isotope.

Target-projectile combinations leading to Z=121 compound nuclei

The below table contains various combinations of targets and projectiles which could hypothetically be used to form compound nuclei with atomic number 121.

Target-projectile combinations leading to Z=121 nuclei

Target	Projectile	CN	Attempt result
238Pu	62Co	300Ubu	Reaction yet to be attempted
208Pb	89Y	297Ubu	Reaction yet to be attempted
232Th	71Ga	303Ubu	Reaction yet to be attempted
238U	65Cu	303Ubu	Reaction yet to be attempted
237Np	64Ni	301Ubu	Reaction yet to be attempted
244Pu	59Co	303Ubu	Reaction yet to be attempted
243Am	58Fe	301Ubu	Reaction yet to be attempted
248Cm	55Mn	303Ubu	Reaction yet to be attempted
249Bk	54Cr	303Ubu	Reaction yet to be attempted
249Cf	51V	300Ubu	Reaction yet to be attempted
254Es	50Ti	304Ubu	Reaction yet to be attempted
258Md	48Ca	306Ubu	Reaction yet to be attempted

References

• doi:10.1063/1.1672054

• doi:10.1002/0470845015.cu0044

• doi:10.1146/annurev.ns.18.120168.000413

See also

• Unbinilium
• Unbibium