Isotopes of beryllium

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)).

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 8Be toward alpha decay, which is favored due to the extremely tight binding of 4He nuclei.

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.

The isotopes 7Be, with a half-life of 53.22(6) d, and 10Be are both cosmogenic nuclides because they are made on a recent timescale in the Solar System by spallation,[4] like 14C.

[12] 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.

The rate of delivery of 7
Be
from the air to the ground in Japan [ 6 ]
Plot showing variations in solar activity, including variation in 10 Be concentration which varies inversely with solar activity. (Note that the beryllium scale is inverted, so increases on this scale indicate lower beryllium-10 levels).