Untribium

Untribium
132Utb
- ↑ Utb ↓ Uoh Extended periodic table untriunium ← untribium → untritrium
Appearance
unknown
General properties
Name, symbol, number	untribium, Utb, 132
Pronunciation	/uːntraɪˈbiəm/
Element category	superactinides
Group, period, block	N/A, 8, g
Mass number	not applicable
Electron configuration	[Uuo] 5g86f28s28p2 (predicted) 2, 8, 18, 32, 40, 20, 8, 4 (predicted)
Physical properties
unknown
Atomic properties
unknown
Most stable isotopes
Main article: Isotopes of untribium
iso NA half-life DM DE (MeV) DP 350Utb (predicted) syn
v • t • e • r

Untribium, Utb, is the temporary name for element 132. Isotopes are predicted within the bands ⁴⁴²Utb to ³⁷⁸Utb, ³⁶⁹Utb to ³⁵⁷Utb, and ³¹⁷Utb to ³⁰⁷Utb. There may be isotopes in the band from the neutron dripline to ⁴⁴³Utb, but it is not possible to predict which ones are possible. Reported half-lives are all less than 1 hr, and most are under 1 sec. Fifty five isotopes within the bands ⁴⁴²Utb to ⁴²⁷Utb (even-N only) and ⁴²⁶Utb to ³⁸⁰Utb are predicted to form. All Utb isotopes which can form, predicted or guessed, will last less than 1000 sec after the event which led to their formation.

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.

GUESSED PROPERTIES

A simple liquid-drop picture indicates that ⁴⁷⁰Utb to ⁴⁴³Utb are unlikely to decay by neutron emission and are stable enough against fission to allow beta decay. Between ⁴⁶⁵Utb and ⁴⁴³Utb, Ref. 3 makes no predictions, but extrapolation from higher Z indicates that it would predict some short-lived, fission-decaying nuclides. Nuclear properties above ⁴⁴²Utb are highly uncertain, but it is likely that some relatively long-lived, beta-decaying isotopes of Utb are possible. It is possible to state that half-lives longer than 1 sec are implausible between the neutron dripline (nominally ⁴⁷⁰Utb) and ⁴⁴³Utb.

PREDICTED PROPERTIES

Even-N isotopes in the band ⁴⁴²Utb - ⁴³³Utb 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⁽⁴⁾, 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 ⁴³²Utb - ⁴²⁷Utb are predicted to decay by a mixture of beta emission and fission, with beta emission dominant in most cases. It appears to be possible for structure to destabilize a nuclide⁽⁵⁾, 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.

Isotopes in the band ⁴²⁶Utb - ⁴²³Utb are predicted to have a dominant fission decay branch, but will probably have a significant beta-decay branch (see above). Predicted half-lives are in the 0.001 - 1 sec range, but will probably be near 0.001 sec.

Most isotopes in the band ⁴²²Utb - ⁴⁰¹Utb are predicted to decay by beta emission with half-lives in the 0.001 - 1 sec range. Fission may be a secondary decay mode, particularly at low A.

Isotopes in the band ⁴⁰⁰Utb to ³⁹⁰Utb are predicted to decay with half-lives in the 0.001 - 1 sec range, except for ³⁹²Utb, whose half-life is < 0.001 sec. Most even-N isotopes decay predominantly by fission and most odd-N isotopes decay by beta emission, although there are exceptions of both kinds. The decay pattern is similar to that for 126 < Z < 135 for nuclides with similar neutron counts.

Between ³⁸⁹Utb and ³⁸⁵Utb, most isotopes decay by fission and have half-lives below 10^-06 sec. ³⁸⁸Utb (an even-N isotope) is an exception, being predicted to decay by beta emission with a half life in the 0.001 - 1 sec range. This pattern, too, appears at comparable neutron counts for 126 < Z < 134.

The band ³⁸⁴Utb to ³⁷⁹Utb contains either beta-emitting isotopes with half lives in the 0.001 - 1 sec range or very short-lived particles which may be nuclides or nuclear drops.

³⁷⁸Utb is predicted to decay by fission with a half-life in the 10^-09 - 10^-06 sec range.

There is a gap from ³⁷⁷Utb to ³⁷⁰Utb in which properties are not reported. These may be short lived nuclides or nuclear drops whose half-life is less than 10^-14 sec. It appears to be the expected destabilized region above N = 228.

Isotopes in the band ³⁶⁹Utb to ³⁶²Utb are predicted to decay by fission. Half-lives increase from <10^-09 sec to the 0.001 - 1 sec range as A declines.

Both ³⁶¹Utb and ³⁶⁰Utb are predicted to decay by alpha emission with half-lives in the 0.001 - 1 sec band. Neutron count for the latter is 228.

³⁵⁹Utb and ³⁵⁷Utb are predicted to decay by fission, the first with a half-life in the 10^-06 - 0.001 sec range and the second with a half-life in the 10^-09 - 10^-06 sec range. ³⁵⁸Utb is probably a fission-decaying isotope with half-life < 10^-09 sec. This is somewhat unexpected, given that neutron shell closures at N = 184 and 308 produce relatively stable, alpha-decaying nuclides below the "magic" number.

Between ³⁵⁶Utb and ³¹⁸Utb there is a gap, which may contain short-lived isotopes or nuclear drops which decay in less than 10^-14 sec.

Between ³¹⁷Utb and ³⁰⁷Utb band, most particles are fission-decaying isotopes with half-lives in the 10^-09 - 10^-06 sec range. ³¹⁵Utb and ³¹³Utb, though, have half-lives in the 10^-06 - 0.001 sec range. ³¹⁰Utb and ³⁰⁸Utb have half-lives below 10^-09 sec.

N = 258 CLOSURE

The model used to predict decay properties of Utb isotopes has a relatively weak neutron shell closure at N = 258. Some neutron-dripline studies have indicated a strong closure at N = 258. If that closure is strong, some isotopes in the band from ³⁹⁰Utb to ³⁸⁰Utb may decay by beta emission rather than the fission predicted. Their half-lives are expected to be short, but they are significant as precursors to potentially-long-lived nuclides in the vicinity of ³⁹⁶Uto.

These are not predictions of decay properties for nuclides in the vicinity of N = 258. The entire exercise is qualitative guesswork. No numbers, but a tantalizing hint of what might be.

OCCURRENCE

FORMATION

Where nuclear drops between the neutron dripline (nominally ⁴⁷⁰Utb) and ⁴⁴³Utb 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. Since some of these chains may be terminated by short-lived, fission-decaying nuclides, it is not possible to say which isotopes of Utb in this range can form.

All even-N nuclear drops in the band ⁴⁴²Utb to ⁴²⁷Utb are predicted to be nuclides. Nearly all nuclear drops in the bands ⁴²⁶Utb to ³⁷⁸Utb, ³⁶⁹Utb to ³⁵⁷Utb, and ³¹⁷Utb to ³⁰⁷Utb are predicted to be nuclides. 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, 55 predicted isotopes; even-N isotopes between ⁴⁴²Utb and ⁴²⁷Utb and all isotopes between ⁴²⁶Utb and ³⁸⁰Utb; can form.

Neutron capture may be able to produce nuclides up to A around 360 before fission attrition stops further growth. It is likely that neutron capture can form the lightest of those Utb isotopes which can form, but unlikely that it can form heavier isotopes.

PERSISTENCE

⁴⁰¹Utb and heavier isotopes will vanish within 1000 sec after a 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.

⁴⁰⁰Utb to ³⁶⁴Utb lie at higher Z than the terminations of beta-decay chains that would populate them. In all cases, chains end in short-lived, fission-decaying nuclides.

³⁶³Utb to ³⁵³Utb lie at higher Z than the terminations of beta-decay chains that would populate them. Beta-decay chains end in long-lived nuclides (at lower Z), which decay by either fission or alpha emission.

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

Calculations done under maximum half-life assumptions and with all nuclides initially populated still point to all isotopes of Utb vanishing within 10^5.5 (3.16E05) sec.

N = 258 SHELL CLOSURE

Even with a strong closure at N = 258, no isotopes of Utb are likely to persist for more than a few seconds.

ATOMIC PROPERTIES

Utb is expected to be an 8th period active metal (superactinide). Its consensus electron configuration has been predicted⁽⁶⁾ to be [Og] 5g⁷ 6f³ 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. "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. "Magic Numbers of Ultraheavy Nuclei"; Vitali Denisov; Physics of Atomic Nuclei; researchgate.net/publications/225734594; July 2005.

6. "Extended Periodic Table", Wikipedia.

7. 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

(07-22-20)