Unquadseptium, Uqs, is the temporary name for element 147. Isotopes are predicted between 476Uqs and 412Uqs. Reported half-lives are all less than 1 hr, and most are under 1 sec. Predicted isotopes in the band 456Uqs to 447Uqs, as well as 423Uqs and 421Uqs may form. All isotopes except 423Uqs and 421Uqs will become extinct in less than 1000 sec after the event which led to their formation. Those isotopes will vanish within 2 days.
NUCLEAR PROPERTIES
Between Z = 175 and Z near 130, one set of predictions for half-life and principal decay mode has been published(1). Ref. 1 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 10-09 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 10-09 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 10-03 sec, even for highly energetic decays, so there is little uncertainty about neutron-rich nuclides.
Ref. 1 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" (this wiki) 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" (this wiki). 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
Ref. 1 predicts isotopes ranging from 476Uqs to 412Uqs. Format used to display isotope properties is: isotope(s); half-life in seconds; dominant decay mode; comments.
476Uqs - 467Uqs; <10^-06; fission.
466Uqs - 464Uqs; 0.001 - 1; fission. A fission half-life this long is plausible only if there is a shell closure at N = 318(2). It is too far above N = 308 for stabilization against fission. Beta decay seems more likely.
463Uqs - 441Uqs; 0.001 - 1; beta.
440Uqs - 438Uqs; 1 - 1000; fission. Ref 1 predicts a band of fission-decaying nuclides with N between 285 and 295. It appears to be possible for structure to destabilize a nuclide(3), so short partial half-lives against fission in this region are plausible. The half-lives predicted in this band, though, seem high, since beta-decaying isotopes immediately above and below it have shorter half-lives and beta decay doesn't appear to be significantly affected by nuclear structure(4).
437Uqs - 435Uqs; 0.001 - 1; beta.
434Uqs - 431Uqs; 0.001 - 1000; fission. The band from 434Uqs to 430Uqs is difficult to understand. Odd-N isotopes are reported to decay by fission and even -N isotopes are reported to decay by beta emission. Since odd-odd nuclides are usually particularly resistant to fission, they should be the ones for which beta-decay is the dominant mode. Half-lives are reasonable, if half-lives for all are in the vicinity of 1 sec.
430Uqs; 0.001 - 1; alpha. This nuclide is masked by a fissility curve, so its properties must be estimated from adjacent nuclides. Half-life is likely to be in the range indicated, but decay mode is just a guess.
429Uqs; 1 - 1000; fission. Since adjacent isotopes of Uqs decay more quickly by alpha emission, the reported half-life is likely only if it is close to 1 sec.
428Uqs - 426Uqs; 0.001 - 1; alpha. Fission and beta emission are likely to be significant.
425Uqs - 419Uqs; 1 - 1000; alpha.
418Uqs; 0.001 - 1; fission. It is unexpected to find a short-lived, odd-N isotope sandwiched between longer lived, alpha-decaying isotopes of Uqs.
417Uqs; 1 - 1000 ; alpha.
416Uqs - 412Uqs; <10-06; fission.
This pattern is generally to be expected, given a neutron shell closure at N = 308. Presence of a fission-decaying band in the N = 285 - 295 range indicates requires nuclear structure.
GUESSED PROPERTIES
(does not apply for this element)
OCCURRENCE
FORMATION
Nuclear drops 476Uqs to 472Uqs and all the drops in the band 469Uqs to 412Uqs are predicted to be nuclides. They are all too far from the neutron dripline to form directly. All beta-decay chains which would lead to 457Uqs or heavier isotopes are terminated at Z < 147 by nuclides which fission so quickly that no beta-decay branch is possible.
In order to determine whether 456Uqs and lighter isotopes can form, it is necessary to model the evolution of initial material by radioactive decay. Details of the model are provided in "Nuclear Decay Chains at High A" in this wiki. Per that model, 12 isotopes; 456Uqs to 447Uqs, 423Uqs, and 421Uqs; can form. The last two of these result from all cells in the model being populated at time zero.
It is implausible that neutron capture can form any Uqs isotope.
PERSISTENCE
457Uqs and heavier isotopes will decay to nothing within 1000 sec after a neutron star merger which led to their formation.
456Uqs through 447Uqs, are all part of long-lived decay chains, but have half-lives under 1 sec themselves and no precursors whose half-lives exceed 1 sec. All will vanish within 1000 sec.
446Uqs to 418Uqs are blocked from forming via beta decay from the dripline by fission at Z < 147.
417Uqs has a predicted half-life in the 1 - 1000 sec range, but cannot be populated via beta decay because 417Uqh decays by fission with a 0.001 - 1 second half-life range.
No other isotopes of Uqs persist for a significant time.
Calculations done under maximum half-life assumptions and with all nuclides initially populated still point to all isotopes of Uqs vanishing within 105.5 (3.16E05) sec.
ATOMIC PROPERTIES
Electron structure of Uqs has been predicted by several sources (see "Extended Periodic Table" in Wikipedia). However, these predictions should be used with caution. Uqs is large enough that nuclear shape may have an effect on electron structure, which might cause different isotopes of Uqs to have different electronic structures. (That means it is no longer an element in the chemical sense.)
If this effect is small, Uqs will be an active (superactinide) metal of the 8th period. Its electron configuration has been predicted(5) to be [Og] 5g18 6f5 7d2 8s2 8p21/2.
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. “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.
3. "Magic Numbers of Ultraheavy Nuclei"; Vitali Denisov; Physics of Atomic Nuclei; researchgate.net/publications/225734594; July 2005.
4. "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".
5. "Extended Periodic Table", Wikipedia.
6. Other references are found in the wiki articles cited.
9-Period Periodic Table of Elements | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 | 1 H |
2 He | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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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 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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(06-23-20)