the element 90sr undergoes beta decay to form yttrium - 90 isotope.
the element 90sr undergoes beta decay to form yttrium - 90 isotope.
the element 90sr undergoes beta decay to form which isotope?
yttrium - 90
Na
Na
unstable isotopes decay to their daughter products (which may sometimes be even more unstable) at a given rate; eventually, often after a series of decays, a stable isotope is reached: there are about 200 stable isotopes in the universe. stable isotopes have ratios of neutrons to protons in their nucleus which are typical about 1 for light elements (e.g. 1 in helium-4) and gradually increase to around 1.5 for the heaviest elements such as lead (e.g. 1.536 in lead-208). no nuclide heavier than lead-208 is stable; these heavier elements have to shed weight to achieve stability, most usually as alpha decay. the other common decay method for isotopes with a high neutron to proton ratio (n/p) is beta decay, in which the nuclide changes elemental identity while keeping the same weight and lowering its n/p ratio. for some isotopes with a relatively low n/p ratio, there is an inverse beta decay, by which a proton is transformed into a neutron, thus moving towards a stable isotope; however, since fission almost always produces products which are neutron heavy, positron emission is relatively rare compared to electron emission. there are many relatively short beta decay chains, at least two (a heavy, beta decay and a light, positron decay) for every discrete weight up to around 207 and some beyond, but for the higher weight elements (isotopes heavier than lead) there are only four pathways which encompass all decay chains. this is because there are just two main decay methods: alpha radiation, which reduces the weight by 4 atomic mass units (amu), and beta, which does not change the atomic weight at all (just the atomic number and the p/n ratio). the four paths are termed 4n, 4n + 1, 4n + 2, and 4n + 3; the remainder from dividing the atomic weight by four gives the chain the isotope will use to decay. there are other decay modes, but they invariably occur at a lower probability than alpha or beta decay. (it should not be supposed that these chains have no branches: the diagram below shows a few branches of chains, and in reality there are many more, because there are many more isotopes possible than are shown in the diagram.) for example, the third atom of nihonium-278 synthesised underwent six alpha decays down to mendelevium-254, followed by an electron capture (a form of beta decay) to fermium-254, and then a seventh alpha to californium-250, upon which it would have followed the 4n + 2 chain as given in this article. however, the heaviest superheavy nuclides synthesised do not reach the four decay chains, because they reach a spontaneously fissioning nuclide after a few alpha decays that terminates the chain: this is what happened to the first two atoms of nihonium-278 synthesised, as well as to all heavier nuclides produced.
decay chain