Unbiunium

This article is about an undiscovered element. Once it is discovered, this article will be edited with more information.

Unbiunium
121Ubu
- ↑ Ubu ↓ Extended periodic table unbinilium ← unbiunium → unbibium
Appearance
unknown
General properties
Name, symbol, number	unbiunium, Ubu, 121
Pronunciation	/uːnbaɪˈuːniəm/
Element category	superactinides
Group, period, block	N/A, 8, g
Mass number	[319] (predicted)
Electron configuration	[Og] 8s2 8p1 (predicted) 2, 8, 18, 32, 32, 18, 8, 3 (predicted)
Physical properties
unknown
Atomic properties
unknown
Most stable isotopes
Main article: Isotopes of unbiunium
iso NA half-life DM DE (MeV) DP 319Ubu (predicted) see text 1 sec - 1 d fission
v • t • e • r

Unbiunium, Ubu, is the temporary name for element 121. Isotopes are predicted between the dripline and ³³⁹Ubu; ³³⁷Ubu; between ³¹⁹Ubu and ³¹⁷Ubu;and between ³¹⁶Ubu and ²⁸³Ubu. All of them have half-lives less than 1 day, and most are under 1 sec. None of its isotopes will persist longer than 1000 sec after the event which caused them to form.

Wikipedia has an article called Unbiunium. This article focuses on things Wikipedia's doesn't stress.

NUCLEAR PROPERTIES

INFORMATION SOURCES

There has been considerable study of the decay properties of Ubu. Most of these have been limited to N < 220, but I know of only one which which reports decay properties of Ubu to the neutron dripline⁽¹⁾. Maps on pp 15 & 18 address the entire (Z,N) region covered, but report only the dominant decay mode and report half-lives only to within a band three orders of magnitude wide (0.001 - 1 sec, for example). More detailed estimates of these properties can be extracted from maps on pp 11 & 12, but only for a limited range of Z and N. Half-life data are reported by colors, which makes numerical estimates laborious to produce. Ref. 1 will be used as the primary reference in this article. Predictions from other sources will be compared to it.

An independent map of half-lives and decay modes exists⁽²⁾. The map shows a stabilized region in a band apparently ending near Z = 132. That band ends at Z = 118. Neutron counts in the region lie between N = 191 and N = 202, but the most stabilized nuclides lie in a band 195 <= N <= 200. Ref. 1 does not show this region.

An interactive site exists which has tables of b-, b+, and alpha decay(1) half-lives for Z up to 135 and A up to 339⁽³⁾. Total half-lives and branch ratios can be computed from these to provide a third pair of maps. This model does not show particular stabilization around N = 200, aligning with Ref. 1 in this regard.

PREDICTED PROPERTIES

Even-N isotopes from the neutron dripline down to ³⁹²Ubu decay predominantly by beta emission with half-lives in the 0.001 - 1 sec range. Half-lives aren't reported, but the properties of beta decay indicate that half-lives close to 0.001 sec are likely⁽³⁾. Odd-N drops in this band decay by neutron emission.

All isotopes in the band ³⁹¹Ubu to ³⁶⁶Ubu are predicted to have half-lives in the 0.001 - 1 sec range. Decay modes are a mixture of fission and beta emission. Which mode dominates depends on N, with specific values of N associated with fission over a range of Z values.

Isotopes in the band ³⁶⁵Ubu to ³⁴¹Ubu are predicted to decay by beta emission and have half-lives in the 0.001 - 1 sec range, except for ³⁴³Ubu, whose half-life is probably a few seconds.

³⁴⁰Ubu to ³³⁶Ubu are predicted to decay by fission. Except for ³⁴⁰Ubu, which has a half-life in the range 0.001 - 1 sec, all have half-lives in the 10^-09 - 10^-06 sec range.

Ref 1 predicts a gap from ³³⁵Ubu to ³¹⁷Ubu, which is predicted to be occupied by nuclear drops or very short-lived nuclides.

Ref, 2 reports isotopes with half-lives above 10^-06 sec in the band ³¹⁹Ubu - ³¹⁶Ubu. Of these, ³¹⁹Ubu has a half-life in the 1 sec - 1 day band (probably under 10^1.5 sec); and all others have half-lives in the 0.001 - 1 sec band. Aside from these it predicts a wide band of isotopes predicted to have half-lives under 10^-06 sec. These can't be compared with Ref. 1 due to the difference in half-life cutoff. All decay by fission. Ref. 2 differs from Rev 1 in predicting long half-lives for isotopes where Ref. 1 predicts short lives. Both agree that fission is the principal decay mode.

Ref 1 predicts ³¹⁵Ubu to ³¹²Ubu will decay by quickly and by fission.

It also predicts that ³¹¹Ubu through ³⁰⁹Ubu should decay by alpha emission with half-lives in the range 10^-06 - 0.001 sec. Ref. 2 predicts fission and shorter half-lives.

Ref. 1 predicts ³⁰⁸Ubu and ³⁰⁷Ubu should decay by alpha emission with half-lives in the range 10^-09 - 10^-06 sec. This dip in half-lives between heavier and lighter isotopes is typical for nuclides with slightly more than a closed shell of neutrons. Ref. 2 predicts fission in this range.

³⁰⁶Ubu to ²⁹⁰Ubu are predicted to decay by alpha emission with half-lives in the 10^-06 - 0.001 sec range. Note that neutron count for ³⁰⁵Ubu is 184.

Most isotopes in the band ²⁸⁹Ubu to ²⁸³Ubu are predicted to decay by alpha emission and have half-lives in the 10^-09 - 10^-06 sec range. Exceptions include ²⁸⁶Ubu, which decays in the 10^-06 - 0.001 sec range, and ²⁸⁵Ubu & ²⁸³Ubu, which are predicted to decay by proton emission.

Wikipedia's article "Unbiunium" also addresses theoretical properties of lighter Ubu isotopes.

OCCURRENCE

FORMATION

All even-N nuclear drops from the neutron dripline to ³⁹²Ubu are predicted to be nuclides. All nuclear drops in the bands ³⁹¹Ubu to ³³⁶Ubu are predicted to be nuclides. Some of the heavier isotopes in that band can form directly as a neutron star disintegrates. Most of them however require a chain of beta decays to form. All isotopes in this band can form; except for ³³⁸Ubu and ³³⁶Ubu, whose beta chains are interrupted at lower Z. Ref 2 shows nuclides in the band from ³¹⁹Ubu to ³¹⁷Ubu. Beta decay chains leading to them are all interrupted. None of them can form. Ref. 1 also predicts all drops in the band ³¹⁶Ubu to ²⁸⁵Ubu are nuclides. None of them can form.

Neutron capture may be able to produce nuclides up to A around 380 before fission attrition stops further growth. Neutron capture is expected to contribute to formation of all significant Ubu isotopes.

PERSISTENCE

³³⁶Ubu and heavier isotopes will vanish within 1000 sec after a supernova or neutron star merger which led to their formation, or lie at higher Z than beta-decay chains which end in nuclides which fission with a half-life not much greater than 1 sec.

³³⁵Ubu through ³¹⁸Ubu lie at a higher Z than the terminating nuclides of short-lived beta-decay chains in this mass range.

³¹⁷Ubu and lighter isotopes are predicted to have short half-lives and to be incapable of forming via beta decay from the dripline.

ATOMIC PROPERTIES

Ubu is expected to be an 8th period active metal. It is normally considered to be the first superactinide. Its electron configuration is expected to be [Og] 8s² 8p¹_1/2.

Wikipedia's article "Unbibium" addresses the element's atomic properties and chemistry in some detail.

REFERENCES

1. "Decay Modes and a Limit of Existence of Nuclei"; H. Koura; 4th Int. Conf. on the Chemistry and Physics of Transactinide Elements; Sept. 2011.

2. “Systematic Study of Decay Properties of Heaviest Elements.”; Y. M. Palenzuelaa, L. F. Ruiza, A. Karpov, and W. Greiner; Bulletin of the Russian Academy of Sciences, Physics.  Vol . 76, No.11, pp 1165 – 1177; 2012

3. "Nuclear Properties for Astrophysical Applications"; P. Moller & J. R. Nix; Los Alamos National Laboratory website; search by "LANL, T2", then "Nuclear Properties for Astrophysical Applications".

4. Other references are found in the wiki articles cited.

9-Period Periodic Table of Elements
1	1 H																																																																	2 He
2	3 Li	4 Be																																																																	5 B	6 C	7 N	8 O	9 F	10 Ne
3	11 Na	12 Mg																																																																	13 Al	14 Si	15 P	16 S	17 Cl	18 Ar
4	19 K	20 Ca																																																																	21 Sc	22 Ti	23 V	24 Cr	25 Mn	26 Fe	27 Co	28 Ni	29 Cu	30 Zn	31 Ga	32 Ge	33 As	34 Se	35 Br	36 Kr
5	37 Rb	38 Sr																																																																	39 Y	40 Zr	41 Nb	42 Mo	43 Tc	44 Ru	45 Rh	46 Pd	47 Ag	48 Cd	49 In	50 Sn	51 Sb	52 Te	53 I	54 Xe
6	55 Cs	56 Ba																																																					57 La	58 Ce	59 Pr	60 Nd	61 Pm	62 Sm	63 Eu	64 Gd	65 Tb	66 Dy	67 Ho	68 Er	69 Tm	70 Yb	71 Lu	72 Hf	73 Ta	74 W	75 Re	76 Os	77 Ir	78 Pt	79 Au	80 Hg	81 Tl	82 Pb	83 Bi	84 Po	85 At	86 Rn
7	87 Fr	88 Ra																																																					89 Ac	90 Th	91 Pa	92 U	93 Np	94 Pu	95 Am	96 Cm	97 Bk	98 Cf	99 Es	100 Fm	101 Md	102 No	103 Lr	104 Rf	105 Db	106 Sg	107 Bh	108 Hs	109 Mt	110 Ds	111 Rg	112 Cn	113 Nh	114 Fl	115 Mc	116 Lv	117 Ts	118 Og
8	119 Uue	120 Ubn																															121 Ubu	122 Ubb	123 Ubt	124 Ubq	125 Ubp	126 Ubh	127 Ubs	128 Ubo	129 Ube	130 Utn	131 Utu	132 Utb	133 Utt	134 Utq	135 Utp	136 Uth	137 Uts	138 Uto	139 Ute	140 Uqn	141 Uqu	142 Uqb	143 Uqt	144 Uqq	145 Uqp	146 Uqh	147 Uqs	148 Uqo	149 Uqe	150 Upn	151 Upu	152 Upb	153 Upt	154 Upq	155 Upp	156 Uph	157 Ups	158 Upo	159 Upe	160 Uhn	161 Uhu	162 Uhb	163 Uht	164 Uhq	165 Uhp	166 Uhh	167 Uhs	168 Uho	169 Uhe	170 Usn	171 Usu	172 Usb
9	173 Ust	174 Usq
Alkali metal Alkaline earth metal Lanthanide Actinide Superactinide Transition metal Post-transition metal Metalloid Other nonmetal Halogen Noble gas predicted predicted predicted predicted predicted predicted predicted predicted predicted

(09-16-20)