Nobelium

Nobelium, No, is the name of element 102. Wikipedia has an article which provides a lot of information about the element.  This article will focus on things Wikipedia does not stress: heavy isotopes and formation.

It has the lowest atomic number of any element whose peak in stability lies among predicted, rather than observed, isotopes. Half-lives of No isotopes may range up to 20 days, The longer-lived isotopes may survive long enough to form dust in a supernova or neutron star merger remnant. The quantity would be minute, though, and probably undetectable.

A good deal of is known about the chemistry of No, both theoretically and experimentally. We also can produce atoms at a rate high enough to be described as "production" in Wikipedia.

NUCLEAR PROPERTIES

INFORMATION SOURCES

Japan Atomic Energy Agency (JAEA) maintains an on-line chart of nuclides which includes decay properties of many predicted nuclides⁽¹⁾ - unlike charts published by Korea Atomic Energy Research Institute (KAERI) or the (U.S.) National Nuclear Data Center (NNDC). This chart gives separate numerical values for partial half-lives against fission, beta emission (both b^- and b⁺), and alpha emission. This reference provides the most focused look at the most significant predicted No isotopes.

An independent resource is provided by the U.S.'s Los Alamos National Laboratory (LANL) in interactive tables of contains tabulated partial half-life data for alpha and beta decay⁽²⁾ for numerous nuclides. The great weakness of this source is that it does not consider fission.

A third source describes decay properties of a large number of nuclides⁽³⁾. Half-life data in this source are presented via color, which makes specifying a value within an order of magnitude difficult. In addition, only the dominant decay mode is reported. Charts on pp 11 - 13 are the most valuable part of the document.

PREDICTED PROPERTIES

Isotopes from the neutron dripline down to ²⁷³No are predicted to decay primarily by beta emission. Half lives increase, as A declines, from around 0.001 sec at the dripline to 1 sec near ²⁹⁰No and peaking under 1000 sec at ²⁷⁴No. Isotopes at the light end of this band are likely to decay by a mixture of beta emission and fission. (Ref. 2 predicts long half-lives between ²⁸⁶No and ²⁸²No. In light of shorter beta partial half-lives it predicts at lower A, these results appear to be anomalous.)

Between ²⁷²No and ²⁶⁸No, the predominant mode of decay is predicted to be fission, although a beta-decay branch is predicted for odd-N isotopes in this band. Half lives are millisecond-scale, although ²⁶⁹No may have a half-life as high as 10 sec.

²⁶⁷No is predicted to decay by a mixture of beta emission and fission, with a weak alpha branch also present. Its half-life may be as much as 2 hr.

Isotopes in the band ²⁶⁶No to ²⁶³No, plus ²⁶¹No are predicted to decay by a combination of fission and alpha emission, with no beta-decay branches. (²⁶¹No is predicted to have a (b+) branch.) Half-lives of ²⁶⁶No and ²⁶⁵No are predicted to be up to 20 days, while half-lives of ²⁶⁴No and ²⁶³No are predicted to be on the order of a day. Beta stability is predicted for this band, making it possibly the region of greatest stability for No. ²⁶¹No is predicted to have a half-life on the order of 2 hr.

²⁶²No has been observed to decay by fission with a half-life around 0.005 sec. This is far shorter than expected, based on predictions. It calls into question the validity of predictions made above for relatively long fission partial half-lives (and presence of other decay modes) for isotopes in the ²⁷⁰No to ²⁶¹No band.

Isotopes have been predicted or observed down to ²³⁷No. Between ²³⁶No and ²³⁰No, there is a gap containing nuclides with half-lives in the 10^-14 - 10^-09 sec range or nuclear drops too short-lived to qualify as nuclides. Decay by fission is to be expected.

Ref. 3 predicts that two set of isotopes with N near 126, ²²⁹No to ²²⁷No and ²²³No to ²²¹No will have half-lives exceeding 10^-09 sec. All are short lived, with some decaying predominantly by fission and some predominantly by alpha emission.

OCCURRENCE

FORMATION

It appears likely that No isotopes from the neutron dripline down to ²⁶⁹No can form. Some losses due to fission in beta-decay chains leading to No is likely, but are not expected to be severe.

It appears likely that ²⁶⁸No cannot form, due to lack of a beta decay branch in ²⁶⁸Fm.

Although fission reduces the amount which can form, it appears to be possible that isotopes in the band ²⁶⁷No to ²⁶³No can form.

²⁶²No cannot form because ²⁶²Fm does not have a beta-decay branch. ²⁶¹No cannot form because ²⁶¹Md has no beta decay branch. ²⁶⁰No to ²⁵⁸No cannot form due to rapid fission in ²⁶⁰Fm to ²⁵⁸Fm. It is unlikely that lighter isotopes can form.

Both neutron star mergers and supernovae contribute to the production of all No isotopes which can form. Slow neutron capture cannot produce any isotopes of No.

PERSISTENCE

The longest-lived isotopes, ²⁶⁶No and ²⁶⁵No may persist, in principle, for up to 8 yrs after a supernova, neutron star merger, or other event which led to their formation. These will survive to become part of the resulting diffuse remnant, although probably not in detectable amounts. Of the remaining isotopes, ²⁶⁷No, ²⁶⁴No, and ²⁶³No may persist, in principle, for a few months.

ATOMIC PROPERTIES

Wikipedia's article "Nobelium" addresses the element's atomic properties and chemistry in some detail. It is possible that No 266 and No 265 may persist long enough to interact chemically.

REFERENCES

1. "Chart of the Nuclides, 2014", Japan Atomic Energy Agency; website available using "chart of nuclides" and "JAEA" as internet search terms.

2. "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".

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. "Isotopes of Nobelium", Wikipedia article.

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

(11-17-20)