Search results
Results from the WOW.Com Content Network
The intermediates in the thorium-232 decay chain are all relatively short-lived; the longest-lived intermediate decay products are radium-228 and thorium-228, with half lives of 5.75 years and 1.91 years, respectively. All other intermediate decay products have half lives of less than four days. [5] The following table lists the intermediate ...
232 Th is the only primordial nuclide of thorium and makes up effectively all of natural thorium, with other isotopes of thorium appearing only in trace amounts as relatively short-lived decay products of uranium and thorium. [54]
The four most common modes of radioactive decay are: alpha decay, beta decay, inverse beta decay (considered as both positron emission and electron capture), and isomeric transition. Of these decay processes, only alpha decay (fission of a helium-4 nucleus) changes the atomic mass number ( A ) of the nucleus, and always decreases it by four.
Decay modes in parentheses are still not observed through experiment but are, by their energy, predicted to occur. Numbers in brackets indicate probability of that decay mode occurring in %, tr indicate <0.1%. Spontaneous fission is not shown as a theoretical decay mode for stable nuclides where other modes are possible (see these nuclides).
Most of the time (92%), it undergoes beta plus decay to 230 Th, with a minor (8%) beta-minus decay branch leading to 230 U. It also has a very rare (.003%) alpha decay mode leading to 226 Ac. [10] It is not found in nature because its half-life is short and it is not found in the decay chains of 235 U, 238 U, or 232 Th. It has a mass of 230. ...
Three isotopes are found in nature, 225 Ac, 227 Ac and 228 Ac, as intermediate decay products of, respectively, 237 Np, 235 U, and 232 Th. 228 Ac and 225 Ac are extremely rare, so almost all natural actinium is 227 Ac.
As a member of the neptunium series, it does not occur in nature except as a product of trace quantities of 237 Np and its daughters formed by neutron capture reactions on primordial 232 Th and 238 U. [2] It is much rarer than 227 Ac and 228 Ac, which respectively occur in the decay chains of uranium-235 and thorium-232.
Pages for logged out editors learn more