Unseptbium

Unseptbium
172Usb
Og ↑ Usb ↓ ? Extended periodic table unseptunium ← unseptbium → unsepttrium
Appearance
unknown
General properties
Name, symbol, number	unseptbium, Usb, 172
Pronunciation	/uːnsɛptˈbaɪəm/
Element category	Noble gases (predicted)
Group, period, block	18, 8, p
Mass number	476 (predicted)
Electron configuration	[Og] 5g18 6f14 7d10 8s2 8p21/2 8p43/2 9s2 9p21/2 2, 8, 18, 32, 50, 32, 18, 8, 4
Physical properties
unknown
Atomic properties
unknown
Most stable isotopes
Main article: Isotopes of unseptbium
iso NA half-life DM DE (MeV) DP 582Usb see article 581Usb see article 580Usb see article 579Usb see article 578Usb see article 577Usb see article 576Usb see article 575Usb see article 574Usb see article 573Usb see article 572Usb see article 571Usb see article 570Usb see article 569Usb see article 568Usb see article 567Usb see article 566Usb see article 565Usb see article 564Usb see article 563Usb see article 483Usb syn 10-9-10-6 α 479Usn 482Usb syn 10-9-10-6 α 478Usn 481Usb syn 10-6-0.001 α 477Usn 480Usb syn 10-6-0.001 α 476Usn 479Usb syn 10-6-0.001 α 475Usn 478Usb syn 10-6-0.001 α 474Usn 477Usb syn 10-6-0.001 α 473Usn 476Usb syn 10-6-0.001 α 472Usn 475Usb syn 10-6-0.001 α 471Usn 474Usb syn 10-6-0.001 α 470Usn 473Usb syn 10-6-0.001 α 469Usn 472Usb syn 10-6-0.001 α 468Usn 471Usb syn 10-6-0.001 α 467Usn 470Usb syn 10-6-0.001 fission 469Usb syn 10-9-10-6 α 465Usn 468Usb syn 10-9-10-6 fission 467Usb syn 10-9-10-6 fission 466Usb syn 10-9-10-6 fission 465Usb syn 10-9-10-6 fission
v • t • e • r

Unseptbium, Usb, is the temporary name for element 172. Isotopes are predicted between ⁴⁸⁶Usb and ⁴⁶⁵Usb (excluding probable artifacts), none of which have half-lives exceeding 0.001 sec. None of these predicted isotopes can form. Isotopes in the band ⁵⁸²Usb to ⁵⁶³Usb are likely, most of which may form. All Usb 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. 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 0.001 sec, even for highly energetic decays, so there is little uncertainty about neutron-rich nuclides.

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 approach used for Z = 176 and above can be used at lower Z.

A boundary in the (Z,A) plane is constructed in The Final Element defining a region of that plane outside of which no nuclei exist. It does not predict where nuclei can exist within that region; but the first-order, liquid-drop model used to create that boundary can be used to guess at where nuclides may exist. Criteria used to guide these guesses are described in Nuclear Guesswork. The resulting A(Z) ranges developed should not be considered accurate, but they are consistent from element to element.

Predicted properties

predicts isotopes ranging from ⁵⁰⁴Usb to ⁴⁴⁰Usb.

⁵⁰⁴Usb and ⁵⁰¹Usb appear to be artifacts. N = 318 has been predicted to be a neutron closure, but N = 229 or 232 is far above that closure.

⁵⁰⁰Usb to ⁴⁸⁷Usb 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 ⁴⁸⁶Usb and ⁴⁶⁵Usb. Format used to display these is: isotope(s); half-life in seconds; dominant decay mode; comments.

⁴⁸⁶Usb - ⁴⁸²Usb; 10^-9 - 10^-6; alpha; These are not unrealistic, particularly if N = 318 is also neutron-magic like N = 308,

⁴⁸¹Usb - ⁴⁷¹Usb; 10^-6 - 0.001; alpha.

⁴⁷⁰Usb; 10^-6 - 0.001; fission; This is unusually long-lived for a fission-decaying nucleus, but is not unrealistic.

⁴⁶⁹Usb; 10^-9 - 10^-6; alpha.

⁴⁶⁸Usb - ⁴⁶⁵Usb; 10^-9 - 10^-6; fission.

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

Isotopes are also predicted in the band from ⁴⁴⁸Usb to ⁴⁴⁰Usb is reported to decay mainly by alpha emission and have a half life in the 10^-9 to 10^-6 sec range. Despite their short half-lives, these predictions appear to be artifacts, since they are very neutron-poor and there are no closures reported in this area to stabilize nuclear drops against fission.

Guessed properties

A nuclear drop containing 172 protons and more than 575 neutrons must decay by neutron emission with a half-life under 10^-14 sec. A drop with 172 protons and fewer than 224 neutrons must decay by spontaneous fission with a half-life under 10^-14 sec. Nuclear drops in the band from ⁷⁴⁷Usb to ³⁹⁶Usb are not required to decay either by neutron emission or by fission, so it is possible they will survive the 10^-14 sec needed for them to become nuclides.

Nuclear drops in the band ⁷⁴⁷Usb to ⁶⁷²Usb are likely to decay by neutron emission but are stable against fission. Nuclides in this band are unlikely. Drops in the band ⁶⁷¹Usb to ⁶²⁵Usb are likely to decay by neutron emission and require a moderate amount of structural correction energy. Nuclides in this band are improbable.

Drops in the bands ⁵⁸²Usb to ⁵⁶³Usb and ⁴⁸⁰Usb to ⁴⁷⁹Usb are unlikely to decay by neutron emission and are stable against fission. Nuclides in these bands are likely. Drops in the bands ⁶²⁴Usb to ⁵⁸³Usb, ⁵⁶²Usb to ⁴⁸¹Usb, and ⁴⁷⁸Usb to ⁴⁴⁹Usb are unlikely to decay by neutron emission and require a moderate amount of structural correction energy. Nuclides in these bands are unlikely. Drops in the band ⁴⁴⁸Usb to ³⁹⁶Usb are unlikely to decay by neutron emission but require large structural correction. Nuclides in this band are improbable.

Comparison

The two techniques described above were more or less consistent. does predict far more nuclides than were estimated to be "likely". The technique for estimating where nuclides are likely to exist is conservative.

Occurrence

Formation

⁵⁸²Usb to ⁵⁶³Usb 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.). Heavier Usb isotopes may form directly. Isotopes ⁵⁷⁹Usb to ⁵⁶³Usb are likely to form via beta decay chains from lower Z nuclides, although attrition due to fission or beta+neutron(s) decay can be expected.

Many nuclear drops in the band ⁵⁰⁴Usb to ⁴⁴⁰Usb 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 < 172.

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

Persistence

All Usb 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 Usb has been predicted by several sources (see "Extended Periodic Table" in Wikipedia). However, these predictions should be used with caution. Orbital theory breaks down between Z = 170 and Z = 175. While only the innermost electrons would be qualitatively different, other orbitals are likely to be affected sufficiently to change the ground state occupation. Usb is also large enough that nuclear shape may have an effect on electron structure, which might cause different isotopes of Usb to have different electronic structures. (That means it is no longer an element in the chemical sense.)

If these effects are small, Usb will be a somewhat inert fluid ending the 8th period. Its electron configuration has been predicted to be [Og] 5g¹⁸ 6f¹⁴ 7d¹⁰ 8s² 8p²_1/2 8p⁴_3/2 9s² 9p²_1/2.

References

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

(06-07-20)