^ "Standard Atomic Weights: Beryllium".Notably, its half-life can be artificially lowered by 0.83% via endohedral enclosure ( 60). However, 7ĭecays only via electron capture, a phenomenon to which its unusually long half-life may be attributed. 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. ^ Intermediate product of triple alpha process in stellar nucleosynthesis as part of the path producing 12C.^ Produced in Big Bang nucleosynthesis, but not primordial, as it all quickly decayed to 7Li.^ a b c Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.^ ( ) spin value – Indicates spin with weak assignment arguments.^ Bold symbol as daughter – Daughter product is stable.^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).^ ( ) – Uncertainty (1 σ) is given in concise form in parentheses after the corresponding last digits.less than about 3–4 months in age, or about two half-lives of 7 In sediments is often used to establish that they are fresh, i.e. 7ĭecay in the sun is one of the sources of solar neutrinos, and the first type ever detected using the Homestake experiment. Is transferred from the air to the ground is controlled in part by the weather. These two radioisotopes of beryllium in the atmosphere track the sunspot cycle and solar activity, since this affects the magnetic field that shields the Earth from cosmic rays. The isotopes 7Īre both cosmogenic nuclides because they are made on a recent timescale in the solar system by spallation, like 14 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. Other possible beryllium isotopes have even more severe mismatches in neutron and proton number, and thus are even less stable. , 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. Toward alpha decay, which is favored due to the extremely tight binding of 4īeryllium 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. 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 8 , with a half-life of 650(130) yoctoseconds. All other radioisotopes have half-lives under 15 s, most under 30 milliseconds. With a half-life of 1.387(12) million years and 7 Of the 10 radioisotopes of beryllium, the most stable are 10 There are 25 other monoisotopic elements but all have odd atomic numbers, and even numbers of neutrons. Beryllium is unique as being the only monoisotopic element with both an even number of protons and an odd number of neutrons. 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 9.012 1831(5)). As such, beryllium is considered a monoisotopic element. Beryllium ( 4Be) has 11 known isotopes and 3 known isomers, but only one of these isotopes ( 9
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