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Unhexoctium
168Uho
Fl

Uho

-
unhexseptiumunhexoctiumunhexennium
Appearance
unknown
General properties
Name, symbol, number unhexoctium, Uho, 168
Pronunciation /nhɛksˈɒktiəm/
Element category post-transition metals
Group, period, block 14, 8, p
Mass number [473] (predicted)
Electron configuration [Og] 5g18 6f14 7d10 8s2 8p2 9s2 9p2
(predicted)[1]
2, 8, 18, 32, 50, 32, 18, 4, 4
(predicted)[1]
Physical properties
unknown
Atomic properties
unknown
Most stable isotopes
Main article: Isotopes of unhexoctium
iso NA half-life DM DE (MeV) DP
484Uho
(predicted)
syn 10-9-0.001 s α 480Uhh
483Uho
(predicted)
syn 10-9-0.001 s α 479Uhh
482Uho
(predicted)
syn 10-9-0.001 s α 478Uhh
481Uho
(predicted)
syn 10-9-0.001 s α 477Uhh
480Uho
(predicted)
syn 10-9-0.001 s α 476Uhh
479Uho
(predicted)
syn 10-9-0.001 s α 475Uhh
478Uho
(predicted)
syn 10-9-0.001 s α 474Uhh
477Uho
(predicted)
syn 10-6-0.001 s α 473Uhh
476Uho
(predicted)
syn 0.001-1 s α 472Uhh
475Uho
(predicted)
syn 0.001-1 s α 471Uhh
474Uho
(predicted)
syn 10-6-0.001 s α 470Uhh
473Uho
(predicted)
syn 0.001-1 s α 469Uhh
472Uho
(predicted)
syn 10-6-0.001 s α 468Uhh
471Uho
(predicted)
syn 10-6-0.001 s α 467Uhh
470Uho
(predicted)
syn 10-6-0.001 s α 466Uhh
469Uho
(predicted)
syn 10-6-0.001 s α 465Uhh
468Uho
(predicted)
syn 10-6-0.001 s α 464Uhh
467Uho
(predicted)
syn 10-6-0.001 s α 463Uhh
466Uho
(predicted)
syn 10-6-0.001 s α 462Uhh
465Uho
(predicted)
syn 10-6-0.001 s α 461Uhh
464Uho
(predicted)
syn 10-6-0.001 s α 460Uhh
463Uho
(predicted)
syn 10-6-0.001 s α 459Uhh
462Uho
(predicted)
syn 10-9-10-6 s fission
461Uho
(predicted)
syn 10-9-10-6 s fission
460Uho
(predicted)
syn <10-9 s probably fission
459Uho
(predicted)
syn 10-9-10-6 s fission
458Uho
(predicted)
syn <10-9 s probably fission
457Uho
(predicted)
syn 10-9-10-6 s fission
vter

Unhexoctium, Uho, is the temporary name for element 168. Isotopes are predicted between 484Uho and 457Uho (excluding probable artifacts), none of which have half-lives exceeding 1 sec. None of these predicted isotopes can form. Isotopes in the band 608Uho to 558Uho are likely, most of which may form. All Uho isotopes will be gone less than 1000 sec. after the event which led to their formation.

Nuclear properties[]

Between Z = 175 and Z near 130, one set of predictions for half-life and principal decay mode has been published[2]. [2] is publicly available and can be found via a search by paper title. Anyone interested in this element should study pp 15 and 18, which allow a given element to be understood in the context of adjacent nuclides.

These data are limited to nuclides for which N <= 333. Half-lives are presented in bands covering 3 orders of magnitude (0.001 sec to 1 sec, for instance) and are accurate to within +/- 3 orders of magnitude, which seems rather crude until the enormous extrapolation from what is known is taken into account, Minimum half-life is set at 10-9 sec, rather than 10-14 sec; which introduces a little uncertainty, but not a great deal because fission half-lives tend to transition quickly from values well above 10-9 sec to values well below 10-14 sec; and, while alpha-decay half-lives change more slowly, alpha emission is rarely dominant except where fission is suppressed. Significantly, beta-decay half-lives do not decline far below 10-3 sec, even for highly energetic decays, so there is little uncertainty about neutron-rich nuclides.

[2] does have one significant weakness. Nuclides which are beta-stable are identified by black squares, overwriting decay mode and half-life information. In many cases, these data can be estimated from adjacent nuclides.

No predictions exist for N > 333. The liquid-drop sketch developed in The Final Element for Z = 176 and above can be used to guess at where nuclides with Z < 175 and N > 333 may exist. Probability criteria for this purpose were set in Nuclear Guesswork. Below Z = 171, it is necessary to look only at nuclear drops which are not expected to decay by neutron emission and require only normal amounts of structural correction energy in order to suppress spontaneous fission.

Predicted properties[]

[2] predicts isotopes ranging from 500Uho to 457Uho.

500Uho appears to be an artifact. N = 318 has been predicted[3] to be a neutron closure, but N = 229 or 232 is far above that closure.

499Uho to 485Uho is a gap, which might mean half-lives below 10-9 sec or might mean the model is going ragged at its edges.

The main band lies between 484Uho and 455Uho. Format used to display these is: isotope(s); half-life in seconds; dominant decay mode; comments.

484Uho - 478Uho; 10-9 - 0.001; alpha. (Due to masking by beta-stable nuclides, it is impossible to read predicted half-lives directly.) These are not unrealistic, particularly if N = 318 is also neutron-magic like N = 308.

477Uho; 10-6 - 0.001; alpha.

476Uho - 475Uho; 0.001 - 1; alpha. (Half-life must be estimated from adjacent nuclides.)

474Uho; 10-6 - 0.001; alpha.

473Uho; 0.001 - 1; alpha.

472Uho - 463Uho; 10-6 - 0.001; alpha.

462Uho - 461Uho; 10-9 - 10-6; fission.

460Uho; <10-9; unknown, but probably fission.

459Uho; 10-9 - 10-6; fission.

458Uho; <10-9; unknown, but probably fission.

457Uho; 10-9 - 10-6; fission.

This pattern is to be expected, given a neutron shell closure at N = 308.

Guessed properties[]

Drops in the bands 608Uho to 558Uho and 478Uho to 470Uho are unlikely to decay by neutron emission and are stable against fission. Nuclides in these bands are likely. Drops in the bands 557Uho to 479Uho and 469Uho to 424Uho are unlikely to decay by neutron emission and require a moderate amount of structural correction energy. Nuclides in these bands are unlikely.

Comparison[]

In the region where predictions and guesses overlap, the estimating technique lists only 478Uho to 470Uho as "likely". [2] predicts a much wider band of existing Uho isotopes.

Occurence[]

Formation[]

608Uho to 558Uho are likely to be nuclides. Depending on the neutron dripline's actual location, nuclei in this A range may form when material over 700 - 800 meters deep is ejected from a neutron star during a merger. (See Neutron Star.) Isotopes in this band may form directly or via beta decay chains from lower Z nuclides. Attrition from decay chains due to fission or beta+neutron(s) emission can be expected.

Many nuclear drops in the band 500Uho to 457Uho are predicted to be nuclides. They are all too far from the neutron dripline to form directly, and cannot form from lower Z nuclides because beta decay chains terminate at Z < 168.

It is implausible that neutron capture can form any Uho isotope.

Persistence[]

All Uho isotopes are expected to decay away to nothing within 1000 sec after the neutron star merger which led to their formation.

Atomic properties[]

Electron structure of Uho has been predicted by several sources (see "Extended Periodic Table" in Wikipedia). However, these predictions should be used with caution. Uho is large enough that nuclear shape may have an effect on electron structure, which might cause different isotopes of Uho to have different electronic structures. (That means it is no longer an element in the chemical sense.)

If this effect is small, Uho will be a p-block metal of the 8th period. Its electron configuration has been predicted[4] to be [Og] 5g18 6f14 7d10 8s2 8p21/2 9s2 9p21/2.

At one time, Uho was thought to complete Period 8 as the noble fluid, but this is no longer thought true.

References[]

  1. 1.0 1.1 Electron configurations of the elements (data page) - Wikipedia
  2. 2.0 2.1 2.2 2.3 2.4 "Decay Modes and a Limit of Existence of Nuclei"; H. Koura; 4th Int. Conf. on the Chemistry and Physics of Transactinide Elements; Sept. 2011.
  3. The Highest Limiting Z in the Extended Periodic Table”; Y.K. Gambhir, A. Bhagwat, and M. Gupta; Journal of Physics G: Nuclear and Particle Physics. 42 (12): 125105. DOI:10.1088/0954 3899/42/12/ 125105.
  4. "Extended periodic table", Wikipedia. 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

(06-8-20)

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