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Beryllium (₄Be) has 11 known isotopes and 3 known isomers, but only one of these isotopes (
Be
) is stable and a primordial nuclide. As such, beryllium is considered a monoisotopic element. It is also a mononuclidic element, because its other isotopes have such short half-lives that none are primordial and their abundance is very low (standard atomic weight is 9.0121831(5)). Beryllium is unique as being the only monoisotopic element with both an even number of protons and an odd number of neutrons. There are 25 other monoisotopic elements but all have odd atomic numbers, and even numbers of neutrons.

Of the 10 radioisotopes of beryllium, the most stable are
Be
with a half-life of 1.387(12) million years and
Be
with a half-life of 53.22(6) d. All other radioisotopes have half-lives under 15 s, most under 30 milliseconds. The least stable isotope is
Be
, with a half-life of 650(130) yoctoseconds.

The 1:1 neutron–proton ratio seen in stable isotopes of many light elements (up to oxygen, and in elements with even atomic number up to calcium) is prevented in beryllium by the extreme instability of
Be
toward alpha decay, which is favored due to the extremely tight binding of
He
nuclei. The half-life for the decay of
Be
is only 81.9(3.7) attoseconds.

Beryllium is prevented from having a stable isotope with 4 protons and 6 neutrons by the very lopsided neutron–proton ratio for such a light element. Nevertheless, this isotope,
Be
, has a half-life of 1.387(12) million years, which indicates unusual stability for a light isotope with such a large neutron/proton imbalance. Other possible beryllium isotopes have even more severe mismatches in neutron and proton number, and thus are even less stable.

Most
Be
in the universe is thought to be formed by cosmic ray nucleosynthesis from cosmic ray spallation in the period between the Big Bang and the formation of the Solar System. The isotopes
Be
, with a half-life of 53.22(6) d, and
Be
are both cosmogenic nuclides because they are made on a recent timescale in the Solar System by spallation, like
C
.

List of isotopes

1. Be – Excited nuclear isomer.
2. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
3. # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
4. Modes of decay:

   EC:	Electron capture
   IT:	Isomeric transition
   n:	Neutron emission
   p:	Proton emission

5. Bold symbol as daughter – Daughter product is stable.
6. ( ) spin value – Indicates spin with weak assignment arguments.
7. This isotope has not yet been observed; given data is inferred or estimated from periodic trends.
8. ^ Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.
9. Produced in Big Bang nucleosynthesis, but not primordial, as it all quickly decayed to Li
10. ^ cosmogenic nuclide
11. Intermediate product of triple alpha process in stellar nucleosynthesis as part of the path producing C
12. Also often considered spontaneous fission, as
    Be
    splits into two equal
    He
    nuclei
13. Has 1 halo neutron
14. Has 4 halo neutrons

Beryllium-7

Beryllium-7 is an isotope with a half-life of 53.3 days that is generated naturally as a cosmogenic nuclide. The rate at which the short-lived
Be
is transferred from the air to the ground is controlled in part by the weather.
Be
decay in the Sun is one of the sources of solar neutrinos, and the first type ever detected using the Homestake experiment. Presence of
Be
in sediments is often used to establish that they are fresh, i.e. less than about 3–4 months in age, or about two half-lives of
Be
.

Beryllium-10

Beryllium-10 has a half-life of 1.39×10 y, and decays by beta decay to stable boron-10 with a maximum energy of 556.2 keV. It is formed in the Earth's atmosphere mainly by cosmic ray spallation of nitrogen and oxygen. Be and its daughter product have been used to examine soil erosion, soil formation from regolith, the development of lateritic soils and the age of ice cores. Be is a significant isotope used as a proxy data measure for cosmogenic nuclides to characterize solar and extra-solar attributes of the past from terrestrial samples.

Decay chains

Most isotopes of beryllium within the proton/neutron drip lines decay via beta decay and/or a combination of beta decay and alpha decay or neutron emission. However,
Be
decays only via electron capture, a phenomenon to which its unusually long half-life may be attributed. Notably, its half-life can be artificially lowered by 0.83% via endohedral enclosure (Be@C₆₀). Also anomalous is
Be
, which decays via alpha decay to
He
. This alpha decay is often considered fission, which would be able to account for its extremely short half-life.

${\displaystyle {\begin{array}{l}{}\\{\ce {^{5}_{4}Be->{^{4}_{3}Li}+{^{1}_{1}H}}}\\{\ce {^{6}_{4}Be->{^{4}_{2}He}+{2_{1}^{1}H}}}\\{\ce {{^{7}_{4}Be}+e^{-}->{^{7}_{3}Li}}}\\{\ce {^{8}_{4}Be->{2_{2}^{4}He}}}\\{\ce {^{10}_{4}Be->{^{10}_{5}B}+e^{-}}}\\{\ce {^{11}_{4}Be->{^{11}_{5}B}+e^{-}}}\\{\ce {^{11}_{4}Be->{^{7}_{3}Li}+{^{4}_{2}He}+e^{-}}}\\{\ce {^{12}_{4}Be->{^{12}_{5}B}+e^{-}}}\\{\ce {^{12}_{4}Be->{^{11}_{5}B}+{^{1}_{0}n}+e^{-}}}\\{\ce {^{13}_{4}Be->{^{12}_{4}Be}+{^{1}_{0}n}}}\\{\ce {^{14}_{4}Be->{^{13}_{5}B}+{^{1}_{0}n}+e^{-}}}\\{\ce {^{14}_{4}Be->{^{14}_{5}B}+e^{-}}}\\{\ce {^{14}_{4}Be->{^{12}_{5}B}+{2_{0}^{1}n}+e^{-}}}\\{\ce {^{15}_{4}Be->{^{14}_{4}Be}+{^{1}_{0}n}}}\\{}{\ce {^{16}_{4}Be->{^{14}_{4}Be}+{2_{0}^{1}n}}}\\{}\end{array}}}$

Notes

1. ^ Note that NUBASE2020 uses the tropical year to convert between years and other units of time, not the Gregorian year. The relationship between years and other time units in NUBASE2020 is as follows: 1 y = 365.2422 d = 31 556 926 s

References

1. ^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
2. "Standard Atomic Weights: Beryllium". CIAAW. 2013.
3. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
4. ^ Mishra, Ritesh Kumar; Marhas, Kuljeet Kaur (2019-03-25). "Meteoritic evidence of a late superflare as source of 7 Be in the early Solar System". Nature Astronomy. 3 (6): 498–505. Bibcode:2019NatAs...3..498M. doi:10.1038/s41550-019-0716-0. ISSN 2397-3366. S2CID 126552874.
5. Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
6. ^ Yamamoto, Masayoshi; Sakaguchi, Aya; Sasaki, Keiichi; Hirose, Katsumi; Igarashi, Yasuhito; Kim, Chang Kyu (January 2006). "Seasonal and spatial variation of atmospheric 210Pb and 7Be deposition: features of the Japan Sea side of Japan". Journal of Environmental Radioactivity. 86 (1): 110–131. doi:10.1016/j.jenvrad.2005.08.001. PMID 16181712.
7. G. Korschinek; A. Bergmaier; T. Faestermann; U. C. Gerstmann (2010). "A new value for the half-life of Be by Heavy-Ion Elastic Recoil Detection and liquid scintillation counting". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. 268 (2): 187–191. Bibcode:2010NIMPB.268..187K. doi:10.1016/j.nimb.2009.09.020.
8. J. Chmeleff; F. von Blanckenburg; K. Kossert; D. Jakob (2010). "Determination of the Be half-life by multicollector ICP-MS and liquid scintillation counting". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. 268 (2): 192–199. Bibcode:2010NIMPB.268..192C. doi:10.1016/j.nimb.2009.09.012.
9. G.A. Kovaltsov; I.G. Usoskin (2010). "A new 3D numerical model of cosmogenic nuclide Be production in the atmosphere". Earth Planet. Sci. Lett. 291 (1–4): 182–199. Bibcode:2010E&PSL.291..182K. doi:10.1016/j.epsl.2010.01.011.
10. J. Beer; K. McCracken; R. von Steiger (2012). Cosmogenic radionuclides: theory and applications in the terrestrial and space environments. Physics of Earth and Space Environments. Vol. 26. Physics of Earth and Space Environments, Springer, Berlin. doi:10.1007/978-3-642-14651-0. ISBN 978-3-642-14650-3. S2CID 55739885.
11. S.V. Poluianov; G.A. Kovaltsov; A.L. Mishev; I.G. Usoskin (2016). "Production of cosmogenic isotopes Be, Be, C, Na, and Cl in the atmosphere: Altitudinal profiles of yield functions". J. Geophys. Res. Atmos. 121 (13): 8125–8136. arXiv:1606.05899. Bibcode:2016JGRD..121.8125P. doi:10.1002/2016JD025034. S2CID 119301845.
12. Balco, Greg; Shuster, David L. (2009). "Al-Be–Ne burial dating" (PDF). Earth and Planetary Science Letters. 286 (3–4): 570–575. Bibcode:2009E&PSL.286..570B. doi:10.1016/j.epsl.2009.07.025. Archived from the original (PDF) on 2015-09-23. Retrieved 2012-12-10.
13. Paleari, Chiara I.; F. Mekhaldi; F. Adolphi; M. Christl; C. Vockenhuber; P. Gautschi; J. Beer; N. Brehm; T. Erhardt; H.-A. Synal; L. Wacker; F. Wilhelms; R. Muscheler (2022). "Cosmogenic radionuclides reveal an extreme solar particle storm near a solar minimum 9125 years BP". Nat. Commun. 13 (214): 214. Bibcode:2022NatCo..13..214P. doi:10.1038/s41467-021-27891-4. PMC 8752676. PMID 35017519.
14. Ohtsuki, T.; Yuki, H.; Muto, M.; Kasagi, J.; Ohno, K. (9 September 2004). "Enhanced Electron-Capture Decay Rate of 7Be Encapsulated in C60 Cages". Physical Review Letters. 93 (11): 112501. Bibcode:2004PhRvL..93k2501O. doi:10.1103/PhysRevLett.93.112501. PMID 15447332. Retrieved 23 February 2022.

v t e Isotopes of the chemical elements
Group 1 2   3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Period Hydrogen and alkali metals Alkaline earth metals Pnicto­gens Chal­co­gens Halo­gens Noble gases ① Isotopes § ListH1 Isotopes § ListHe2 ② Isotopes § ListLi3 Isotopes § ListBe4 Isotopes § ListB5 Isotopes § ListC6 Isotopes § ListN7 Isotopes § ListO8 Isotopes § ListF9 Isotopes § ListNe10 ③ Isotopes § ListNa11 Isotopes § ListMg12 Isotopes § ListAl13 Isotopes § ListSi14 Isotopes § ListP15 Isotopes § ListS16 Isotopes § ListCl17 Isotopes § ListAr18 ④ Isotopes § ListK19 Isotopes § ListCa20 Isotopes § ListSc21 Isotopes § ListTi22 Isotopes § ListV23 Isotopes § ListCr24 Isotopes § ListMn25 Isotopes § ListFe26 Isotopes § ListCo27 Isotopes § ListNi28 Isotopes § ListCu29 Isotopes § ListZn30 Isotopes § ListGa31 Isotopes § ListGe32 Isotopes § ListAs33 Isotopes § ListSe34 Isotopes § ListBr35 Isotopes § ListKr36 ⑤ Isotopes § ListRb37 Isotopes § ListSr38 Isotopes § ListY39 Isotopes § ListZr40 Isotopes § ListNb41 Isotopes § ListMo42 Isotopes § ListTc43 Isotopes § ListRu44 Isotopes § ListRh45 Isotopes § ListPd46 Isotopes § ListAg47 Isotopes § ListCd48 Isotopes § ListIn49 Isotopes § ListSn50 Isotopes § ListSb51 Isotopes § ListTe52 Isotopes § ListI53 Isotopes § ListXe54 ⑥ Isotopes § ListCs55 Isotopes § ListBa56 Isotopes § ListLu71 Isotopes § ListHf72 Isotopes § ListTa73 Isotopes § ListW74 Isotopes § ListRe75 Isotopes § ListOs76 Isotopes § ListIr77 Isotopes § ListPt78 Isotopes § ListAu79 Isotopes § ListHg80 Isotopes § ListTl81 Isotopes § ListPb82 Isotopes § ListBi83 Isotopes § ListPo84 Isotopes § ListAt85 Isotopes § ListRn86 ⑦ Isotopes § ListFr87 Isotopes § ListRa88 Isotopes § ListLr103 Isotopes § ListRf104 Isotopes § ListDb105 Isotopes § ListSg106 Isotopes § ListBh107 Isotopes § ListHs108 Isotopes § ListMt109 Isotopes § ListDs110 Isotopes § ListRg111 Isotopes § ListCn112 Isotopes § ListNh113 Isotopes § ListFl114 Isotopes § ListMc115 Isotopes § ListLv116 Isotopes § ListTs117 Isotopes § ListOg118 ⑧ Isotopes § ListUue119 Isotopes § ListUbn120 Isotopes § ListLa57 Isotopes § ListCe58 Isotopes § ListPr59 Isotopes § ListNd60 Isotopes § ListPm61 Isotopes § ListSm62 Isotopes § ListEu63 Isotopes § ListGd64 Isotopes § ListTb65 Isotopes § ListDy66 Isotopes § ListHo67 Isotopes § ListEr68 Isotopes § ListTm69 Isotopes § ListYb70   Isotopes § ListAc89 Isotopes § ListTh90 Isotopes § ListPa91 Isotopes § ListU92 Isotopes § ListNp93 Isotopes § ListPu94 Isotopes § ListAm95 Isotopes § ListCm96 Isotopes § ListBk97 Isotopes § ListCf98 Isotopes § ListEs99 Isotopes § ListFm100 Isotopes § ListMd101 Isotopes § ListNo102
Table of nuclides Categories: Isotopes Tables of nuclides Metastable isotopes Isotopes by element

• Isotopes of beryllium
• Beryllium
• Lists of isotopes by element