Unbioctium

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

Unbioctium, Ubo, is the temporary name for element 128. Isotopes are predicted within the bands ⁴³⁶Ubo to ³⁵¹Ubo and ³¹⁷Ubo to ²⁹³Ubo. There may be isotopes in the band from the neutron dripline to ⁴³⁷Ubo, but it is not possible to predict which ones are possible. Two long-lived isotopes are predicted: ³⁵⁶Ubo is reported to have a half-life on the order of 10⁰⁶ sec (12 days) and ³⁵⁵Ubo is reported to have a half-life around 10⁰⁵ sec. Other half-lives are all less than 1 hr, and most are under 1 sec. Sixty nine isotopes within the bands ⁴³⁶Ubo to ⁴¹³Ubo (even-N only), ⁴¹²Ubo to ³⁵⁸Ubo, and ³⁵⁶Ubo, are predicted to form directly. ³⁵³Ubo forms as a decay product of ³⁵³Ubh. ³⁵⁶Ubo is expected to persist for approximately 5 years after the event which led to its formation. ³⁵³Ubo is expected to survive for about 6 years. All other Ubo isotopes, predicted or guessed, will last less than 1000 sec.

NUCLEAR PROPERTIES

INFORMATION SOURCES

While studies addressing specific issues have been carried out to very high N⁽¹⁾. and to moderate Z⁽²⁾, (Z,N) or (Z,A) maps predicting half-lives and decay modes are almost completely limited to the region below Z = 130 and N = 220. There appears to be only one such map which extends beyond that region and is accessible⁽³⁾.

(Z,N) maps for half-life and decay mode in Ref. 3 extend as high as Z = 175 and N = 333. Half-lives are reported as bands 3 orders of magnitude wide (0.001 - 1 sec, for example), and should be considered accurate only to within +/- orders of magnitude (presumably from band center. (A nuclide reported to be in the 0.001 - 1 sec band should be considered to have a possible half-life between 10^-4.5 sec and 10^1.5 sec.) Decay modes are limited alpha emission, beta emission, proton emission, and fission; and to the principal one for each nuclide. There are areas where two modes (or more) may be important, meaning that small uncertainties is model parameters could have produced different results. It is also possible that cluster decay may become important above the neutron shell closures at N = 228 and 308.

Ref. 3 does have two significant weakness in the way data are presented. Nuclides which are beta-stable are identified by black squares, overwriting decay mode and half-life information. In addition, nuclides having half-lives less than 10^-09 sec are not reported, which obscures the distinction between nuclides having half-lives in the 10^-09 and 10^-14 sec band and nuclear drops whose half-life is under 10^-14 sec.

Above Z around 126, predictions in Ref. 3 may not reach the neutron dripline. This can be an important limitation because the only processes which can form nuclei at more than atoms / star quantity generate very neutron-rich nuclei. It is possible to to make a crude, but conservative (high N) guess for the dripline's location by averaging predicted values for even-N nuclei.{See "The Final Element" (this wiki).} It is also possible to guess at regions of the (Z,N) or (Z,A) plane in which a fission barrier high enough to permit nuclides exists by using a first-order, liquid drop model. {See "Nuclear Guesswork" (this wiki).} Specific numbers are reported for these guesses, not with the expectation that they are accurate, but because they are consistent from element to element. They allow construction of a map which at least hints at where in the (Z,A) plane nuclides may be found.

An independent map of half-lives and decay modes is provided in Wikipedia⁽⁴⁾. The source referenced, however, did not present maps extending beyond N = 190. Wikipedia's half-life chart did extend to Z = 127 and N = 230, but the scale used lumps half-lives in the range 1 sec to 86400 sec (1 day) into a single category, which blurs an important range in values. It also does not distinguish half-life ranges below 10^-06 sec and gives no indication of certainty. Its decay modes chart goes to Z = 132, but cuts off at N = 204. Cutoffs for individual elements are also different between half-life and decay mode charts. Ref. 4 is decidedly a weaker source than Ref. 3.

GUESSED PROPERTIES

A simple liquid-drop picture indicates that even-N particles from the neutron dripline down to ⁴³⁷Ubo are unlikely to decay by neutron emission and are stable enough against fission to allow beta decay. Ref. 3 makes no predictions for this region, but extrapolation from higher Z indicates that it may predict some short-lived, fission-decaying nuclides. It does seem likely, though, that beta decay will be common for even-N nuclides in this range. Odd-N particles can be expected to be nuclear drops which decay by neutron emission too quickly to qualify as nuclides.

Predicted properties

Even-N isotopes in the band ⁴³⁶Ubo - ⁴³¹Ubo are predicted to decay by beta emission. Since predicted half-lives are in the 10^-06 - 0.001 sec range and beta decay partial half-lives far from stability have a minimum near 0.001 sec⁽⁵⁾, that is about where half-lives should lie. Odd-N nuclear drops are predicted to decay by neutron emission before they have time to become nuclides.

Even-N isotopes in the band ⁴³⁰Ubo - ⁴¹⁹Ubo are predicted to decay by a mixture of beta emission and fission, with fission dominant in most cases. It appears to be possible for structure to destabilize a nuclide⁽⁶⁾, so the data reported appear to be realistic, Half-lives are masked by other features of the map, but the properties of beta decay (see above) indicate that half-lives close to 0.001 sec are likely. Odd-N drops in this band decay by neutron emission.

Even-N isotopes in the band ⁴¹⁸Ubo to ⁴¹³Ubo are predicted to decay by beta emission. Probable half-lives are close to 0.001 sec. Odd-N particles are predicted to be neutron-emitting nuclear drops with half-lives too short to qualify as nuclides.

All isotopes in the ⁴¹²Ubo to ³⁹⁷Ubo band are predicted to decay via beta emission with half-lives in the 0.001 - 1 sec range.

Isotopes in the band ³⁹⁶Ubo - ³⁸⁴Ubo are predicted to have half-lives in the 0.001 - 1 sec range, except for ³⁸⁸Ubo, whose half-life is reported to be in the 10^-06 - 0.001 sec range (but is probably close to 0.001 sec). Decay by fission is slightly more common than other modes in even-N isotopes (4 of 7), while beta emission is the most common mode in odd-N isotopes (3 of 6). The odd-N isotope ³⁸⁷Ubo is reported to decay by alpha emission, unlike any other nuclides in its vicinity. The pattern of decay modes fits reported behavior for nuclides with equal neutron counts in the range 126 < Z < 135.

In the band between ³⁸³Ubo and ³⁶⁸Ubo there are three distinct groups. Three isotopes, ³⁸⁰Ubo, ³⁷⁷Ubo, and ³⁷⁴Ubo are predicted to decay by beta emission with half-lives predicted to lie in the 0.001 - 1 sec range. It is not obvious why these three should be so stable against fission, but they are all similar to nuclides with equal neutron count lying in the 126 < Z < 135 range. Five isotopes, ³⁸²Ubo, ³⁷⁸Ubo, ³⁷⁶Ubo, ³⁷²Ubo, and ³⁷⁰Ubo have half-lives too short to be reported. They are all even-N nuclides, and the only gaps in the sequence lie where long-lived, beta-decaying isotopes are predicted. The remaining 8 isotopes are all reported to decay by fission with half-lives in the 10^-09 - 10^-06 sec range. All are odd-N isotopes, with the exception of ³⁶⁸Ubo. Were it not for the beta-emitting isotopes, the pattern could be accounted for by the stabilizing effect of an odd neutron.

Isotopes in the band ³⁶⁷Ubo to ³⁶²Ubo are predicted to decay by fission. Their half-lives increase from the 10^-06 - 0.001 sec range to the 1 - 1000 sec range as neutron count approaches N = 228. Actual peak half-lives are unlikely to be much greater than 1 sec, even at the low end of this band (see p 12 of Ref. 3).

Most isotopes in the ³⁶¹Ubo to ³⁵⁴Ubo band are predicted to decay by alpha emission, although ³⁶¹Ubo and ³⁵⁷Ubo are reported to beta decay. Most reported half-lives in this band are in the 1 - 1000 sec range, but a few are in the 0.001 - 1 sec range. Ref 3 contains a more detailed map of this region of the (Z,A) plane (see p. 12), which indicates that actual half-lives generally differ less than the reported numbers seem to indicate. However, ³⁵⁵Ubo is predicted to have a half-life on the order of 10⁵ sec (1 day), and ³⁵⁶Ubo - for which N = 228 - has a half-life on the order of 10⁶ sec (roughly 2 weeks). Although it is still expected to decay by alpha emission, ³⁵⁴Ubo is predicted to have a half-life on the order of 0.001 sec; which indicates how rapidly stability declines for N < 228.

Isotopes in the band ³⁵³Ubo to ³⁵¹Ubo are predicted to decay rapidly by fission. This abrupt change in mode and decline in stability is puzzling, given that neutron shell closures at N = 184 and 308 produce relatively stable, alpha-decaying nuclides below the "magic" number.

Between ³⁵⁰Ubo and ³¹⁸Ubo Ref. 3 shows a gap, which may contain short-lived isotopes or nuclear drops which decay in less than 10^-14 sec. This appears to be the instability band expected above N = 184.

Ref, 4 does not show half-life information for Ubo, but the decay modes chart indicates that ³³⁰Ubo to ³²⁵Ubo may have half-lives in the 10^-06 - 0.001 sec range because isotopes in that band are reported to decay by alpha emission and Z = 127 nuclides in this zone have half-lives of that duration.

Ref 3 predicts ³¹⁷Ubo to decay by fission with a half-life in the 10^-09 - 10^-06 sec range.

Isotopes in the ³¹⁶Ubo - ³⁰⁵Ubo band are all predicted in Ref. 3 to decay by fission and have half-lives in the 0.001 - 1 sec range. ³¹²Ubo has a neutron count of 184. This band, forms the center of a small zone of nuclides which are more stable than those surrounding the zone, although it appears half-lives are generally under 0.1 sec. It is not clear what is responsible for this zone, although nuclear shape may play a role.

Isotopes in the band ³⁰⁴Ubo to ²⁹⁶Ubo are predicted in Ref. 3 to decay by fission. Reported half-lives vary in a somewhat random fashion from the 0.001 - 1 sec range to below 10^-09 sec. Only ³⁰³Ubo has a half-life exceeding 0.001 sec.

Ref 3 indicates that proton decay is the dominant mode for ²⁹⁵Ubo and ²⁹³Ubo. Both half-lives are < 0.001 sec. No other isotopes below ²⁹⁶Ubo have half-lives long enough to report.

Ref. 4 shows fission as the predominant decay mode for isotopes ³¹⁷Ubo - ³¹³Ubo. Half-lives are not reported, but data for Ubs imply they are all short. That reference cuts off at ³¹³Ubo.

Occurrence

Formation

Where nuclear drops between the neutron dripline and ⁴³⁷Ubo can be nuclides, they may form. Heavier isotopes may form directly from disintegrating neutron star material, and the remainder may form via beta decay chains from lower-Z nuclides, particularly since beta+neutrons decay is quite likely in this region. Since some of these chains may be terminated by short-lived, fission-decaying nuclides, it is not possible to say which isotopes of Ubo in this range can form.

All even-N nuclear drops in the band ⁴³⁶Ubo to ⁴¹³Ubo are predicted to be nuclides. All nuclear drops in the band ⁴¹²Ubo to ³⁸³Ubo, many drops in the band ³⁸²Ubo to ³⁷⁰Ubo, nearly all drops in the band ³⁶⁹Ubo to ³⁵¹Ubo, and nearly all drops in the band ³¹⁷Ubo to ²⁹³Ubo are predicted by Ref. 3 to be nuclides. To them, Ref 4 would add drops in the band ³³⁰Ubo to ³²⁵Ubo. All are too far from the neutron dripline to form directly. It is possible to simulate the formation of nuclides via decay chains using data from Ref. 3 and assuming an initial distribution close to the neutron dripline. Details of the model are provided in "Nuclear Decay Chains at High A" in this wiki. Per that model, 69 predicted isotopes; even-N isotopes between ⁴³⁶Ubo and ⁴¹³Ubo. all isotopes between ⁴¹²Ubo and ³⁵⁸Ubo, and ³⁵⁶Ubo; can form. Of the two Ubo isotopes with long half-lives, only ³⁵⁶Ubo can form; the beta decay chain leading to ³⁵⁵Ubo is blocked by alpha-decaying ³⁵⁵Ubs. Note that none of the isotopes predicted in Ref. 4 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 but highly neutron-rich Ubo isotopes. It is expected to contribute to formation of ³⁵⁶Ubo.

PERSISTENCE

³⁶⁴Ubo 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.

³⁶³Ubo and ³⁶²Ubo are predicted to decay by fission and have half-lives around 10^0.5 (3.16) sec and to lie at the ends of beta-decay chains from the dripline, all nuclides of which have predicted half-lives under 1 sec. ³⁶³Ubo and ³⁶²Ubo will persist for a time less than 3600 sec.

³⁶¹Ubo is predicted to be short-lived and beta-emitting. It is expected to vanish within 1000 sec after formation.

³⁶⁰Ubo through ³⁵⁸Ubo are predicted to decay by alpha emission, and to have half-lives below 10^0.5 (3.16) sec or less, and to lie at the end of beta-decay chains from the dripline, two of whose members may have half-lives around 10^0.5 (3.16) sec. These three isotopes are expected to decay to nothing within 3600 sec after formation.

³⁵⁷Ubo is predicted to have a long (over 1 sec) half-life, but to be prevented from forming by alpha decay at ³⁵⁷Ubs.

³⁵⁶Ubo is predicted to have a half-life around 10⁶ (1000000) sec and to decay by alpha emission. It, together with ³⁵²Ubh, anchors a long-lived network of decay chains which may persist for up to 21 years. ³⁵⁶Ubo itself is upstream (decays into) ³⁵²Ubh, but it persists for 4 years. That is long enough for ³⁵⁶Ubo and its descendents to become part of a diffuse supernova or neutron star merger remnant which has begun to interact with the interstellar medium around it.

³⁵⁵Ubo and ³⁵⁴Ubo are prevented from forming by alpha decay at ³⁵⁵Ubs and ³⁵⁴Ubh respectively.

³⁵³Ubo terminates a beta-decay chain. A few members of that chain may have half-lives exceeding 1 sec, but all can be expected to vanish within 3600 sec. ³⁵³Ubo itself has a half-life well below 1 sec, so it will not persist longer than that.

If lighter isotopes of Ubo can form, they are not expected to persist significantly.

ATOMIC PROPERTIES

Ubo is expected to be an 8th period active metal (superactinide). Its consensus electron configuration has been predicted to be [Og] 5g⁴ 6f² 8s² 8p²_1/2.

References

1. for example, "Nuclear Energy Density Functionals: What Do We Really Know?"; Aurel Bulgac, Michael McNeil Forbes, and Shi Jin; Researchgate publication 279633220 or arXiv: 1506.09195v1 [nucl-th] 30 Jun 2015.

2. for example "Fission Mechanism of Exotic Nuclei"; Research Group for Heavy Element Nuclear Science; http://asrc.jaea.go.jp/soshiki/gr/HENS-gr/np/research/pageFission_e.html.; 17 Sept 17.

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

4. "Extended Periodic Table", Section 4.3. The figures presented in that section cited "Superheavy Elements: Which Regions of the Nuclear Map are Accessible in the Nearest Studies"; Alexander Karpov, Valery Zagrebaev, and Walter Grenier; SHE-2015 conference at Texas A&M University; 04-01-2015 as their source.

5. "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".

6.  "Magic Numbers of Ultraheavy Nuclei"; Vitali Denisov; Physics of Atomic Nuclei; researchgate.net/publications/225734594; July 2005.

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

(07-23-20)

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

(07-23-20)