Unbiunium

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.

1 Naming
2 Electronic configurations
3 Isotopes
4 Target-projectile combinations leading to Z=121 compound nuclei
5 References
6 See also

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.^[1]

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

^ Eliav, Ephraim; Shmulyian, Sergei; Kaldor, Uzi; Ishikawa, Yasuyuki (1998). "Transition energies of lanthanum, actinium, and eka-actinium (element 121)". The Journal of Chemical Physics 109: 3954. Bibcode 1998JChPh.109.3954E. doi:10.1063/1.476995.

doi:10.1063/1.1672054

doi:10.1002/0470845015.cu0044

doi:10.1146/annurev.ns.18.120168.000413