Английская Википедия:Isotopes of beryllium

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Beryllium (₄Be) has 11 known isotopes and 3 known isomers, but only one of these isotopes (Шаблон:SimpleNuclide) 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 Шаблон:Val). 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 Шаблон:SimpleNuclide with a half-life of Шаблон:Val million yearsШаблон:Refn and Шаблон:SimpleNuclide with a half-life of Шаблон:Val. All other radioisotopes have half-lives under Шаблон:Val, most under Шаблон:Val. The least stable isotope is Шаблон:SimpleNuclide, with a half-life of Шаблон:Val.

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 Шаблон:SimpleNuclide toward alpha decay, which is favored due to the extremely tight binding of [[helium#Related stability of the helium-4 nucleus and electron shell|Шаблон:SimpleNuclide]] nuclei. The half-life for the decay of Шаблон:SimpleNuclide is only Шаблон:Val.

Beryllium is prevented from having a stable isotope with 4 protons and 6 neutrons by the very large mismatch in neutron–proton ratio for such a light element. Nevertheless, this isotope, [[beryllium-10|Шаблон:SimpleNuclide]], has a half-life of Шаблон:Val million yearsШаблон:Refn, 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 Шаблон:SimpleNuclide 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 Шаблон:SimpleNuclide, with a half-life of Шаблон:Val, and Шаблон:SimpleNuclide are both cosmogenic nuclides because they are made on a recent timescale in the Solar System by spallation, like [[carbon-14|Шаблон:SimpleNuclide]].

List of isotopes

Шаблон:Isotopes table |- | Шаблон:SimpleNuclide |4 |1 | Шаблон:Val# | | p ? | Шаблон:SimpleNuclide ? | (1/2+)# | | |- | Шаблон:SimpleNuclide |4 |2 | Шаблон:Val | Шаблон:Val
[[[:Шаблон:Val]]] | 2p | Шаблон:SimpleNuclide | 0+ | | |- | Шаблон:SimpleNuclide |4 |3 | Шаблон:Val | Шаблон:Val | ε | Шаблон:SimpleNuclide | 3/2− | Trace | |- | [[Beryllium-8|Шаблон:SimpleNuclide]] |4 |4 | Шаблон:Val | Шаблон:Val
[[[:Шаблон:Val]]] | α | Шаблон:SimpleNuclide | 0+ | | |- | style="text-indent:1em" | Шаблон:SimpleNuclide | colspan="3" style="text-indent:2em" | Шаблон:Val | | α | Шаблон:SimpleNuclide | 2+ | | |- | Шаблон:SimpleNuclide |4 |5 | Шаблон:Val | colspan=3 align=center|Stable | 3/2− | 1 | |- | style="text-indent:1em" | Шаблон:SimpleNuclide | colspan="3" style="text-indent:2em" | Шаблон:Val | Шаблон:Val
[[[:Шаблон:Val]]] | | | 3/2− | | |- | [[Beryllium-10|Шаблон:SimpleNuclide]] |4 |6 | Шаблон:Val | Шаблон:ValШаблон:Refn | β⁻ | Шаблон:SimpleNuclide | 0+ | Trace | |- | rowspan=3|Шаблон:SimpleNuclide | rowspan=3|4 | rowspan=3|7 | rowspan=3|Шаблон:Val | rowspan=3|Шаблон:Val | β⁻ (Шаблон:Val) | Шаблон:SimpleNuclide | rowspan=3|1/2+ | rowspan=3| | rowspan=3| |- | β⁻α (Шаблон:Val) | Шаблон:SimpleNuclide |- | β⁻p (Шаблон:Val) | Шаблон:SimpleNuclide |- | style="text-indent:1em" | Шаблон:SimpleNuclide | colspan="3" style="text-indent:2em" | Шаблон:Val | Шаблон:Val
[[[:Шаблон:Val]]] | IT ? | Шаблон:SimpleNuclide ? | 3/2− | | |- | rowspan=2|Шаблон:SimpleNuclide | rowspan=2|4 | rowspan=2|8 | rowspan=2|Шаблон:Val | rowspan=2|Шаблон:Val | β⁻ (Шаблон:Val) | Шаблон:SimpleNuclide | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β⁻n (Шаблон:Val) | Шаблон:SimpleNuclide |- | style="text-indent:1em" | Шаблон:SimpleNuclide | colspan="3" style="text-indent:2em" | Шаблон:Val | Шаблон:Val | IT | Шаблон:SimpleNuclide | 0+ | | |- | Шаблон:SimpleNuclide |4 |9 | Шаблон:Val | Шаблон:Val | n ? | Шаблон:SimpleNuclide ? | (1/2−) | | |- | style="text-indent:1em" | Шаблон:SimpleNuclide | colspan="3" style="text-indent:2em" | Шаблон:Val | | | | (5/2+) | | |- | rowspan=5|Шаблон:SimpleNuclide | rowspan=5|4 | rowspan=5|10 | rowspan=5|Шаблон:Val | rowspan=5|Шаблон:Val | β⁻n (Шаблон:Val) | Шаблон:SimpleNuclide | rowspan=5|0+ | rowspan=5| | rowspan=5| |- | β⁻ (> Шаблон:Val) | Шаблон:SimpleNuclide |- | β⁻2n (Шаблон:Val) | Шаблон:SimpleNuclide |- | β⁻t (Шаблон:Val) | Шаблон:SimpleNuclide |- | β⁻α (< Шаблон:Val) | Шаблон:SimpleNuclide |- | style="text-indent:1em" | Шаблон:SimpleNuclide | colspan="3" style="text-indent:2em" | Шаблон:Val | | | | (2+) | | |- | Шаблон:SimpleNuclide |4 |11 | Шаблон:Val | Шаблон:Val | n | Шаблон:SimpleNuclide | (5/2+) | | |- | Шаблон:SimpleNuclide |4 |12 | Шаблон:Val | Шаблон:Val
[[[:Шаблон:Val]]] |2n |Шаблон:SimpleNuclide | 0+ | | Шаблон:Isotopes table/footer

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 Шаблон:SimpleNuclide is transferred from the air to the ground is controlled in part by the weather. Шаблон:SimpleNuclide decay in the Sun is one of the sources of solar neutrinos, and the first type ever detected using the Homestake experiment. Presence of Шаблон:SimpleNuclide 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 Шаблон:SimpleNuclide.

Файл:Be7fromcosmicrays.png

The rate of delivery of Шаблон:SimpleNuclide from the air to the ground in Japan

Beryllium-10

Файл:Solar Activity Proxies.png

Plot showing variations in solar activity, including variation in ¹⁰Be concentration which varies inversely with solar activity. (Note that the beryllium scale is inverted, so increases on this scale indicate lower beryllium-10 levels).

Beryllium-10 has a half-life of Шаблон:Val, 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. ¹⁰Be 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. ¹⁰Be 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, Шаблон:SimpleNuclide 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 (⁷Be@C₆₀). Also anomalous is Шаблон:SimpleNuclide, which decays via alpha decay to Шаблон:SimpleNuclide. This alpha decay is often considered fission, which would be able to account for its extremely short half-life.

<math chem>\begin{array}{l}{}\\

\ce{^5_4Be -> [\ce{Unknown}] {^4_3Li} + {^1_1H}} \\ \ce{^6_4Be -> [5 \ \ce{zs}] {^4_2He} + {2^1_1H}} \\ \ce{{^7_4Be} + e^- -> [53.22 \ \ce{d}] {^7_3Li}} \\ \ce{^8_4Be -> [81.9 \ \ce{as}] {2^4_2He}} \\ \ce{^{10}_4Be -> [1.387 \ \ce{Ma}] {^{10}_5B} + e^-} \\ \ce{^{11}_4Be -> [13.76 \ \ce{s}] {^{11}_5B} + e^-} \\ \ce{^{11}_4Be -> [13.76 \ \ce{s}] {^7_3Li} + {^4_2He} + e^-} \\ \ce{^{12}_4Be -> [21.46 \ \ce{ms}] {^{12}_5B} + e^-} \\ \ce{^{12}_4Be -> [21.46 \ \ce{ms}] {^{11}_5B} + {^1_0n} + e^-} \\ \ce{^{13}_4Be -> [1 \ \ce{zs}] {^{12}_4Be} + {^1_0n}} \\ \ce{^{14}_4Be -> [4.53 \ \ce{ms}] {^{13}_5B} + {^1_0n} + e^-} \\ \ce{^{14}_4Be -> [4.53 \ \ce{ms}] {^{14}_5B} + e^-} \\ \ce{^{14}_4Be -> [4.53 \ \ce{ms}] {^{12}_5B} + {2^1_0n} + e^-} \\ \ce{^{15}_4Be -> [790 \ \ce{ys}] {^{14}_4Be} + {^1_0n}} \\{} \ce{^{16}_4Be -> [650 \ \ce{ys}] {^{14}_4Be} + {2^1_0n}} \\{} \end{array}</math>