uncertainties
121Isotopes of uranium — Uranium (U) is a naturally occurring element with no stable isotopes. In other words, all uranium is radioactive and hence vanishing by radioactive decay, yet it is also found in great quantity in the earth s crust. The natural isotopes are… …
122Isotopes of protactinium — Protactinium (Pa) Standard atomic mass: 231.03588(2) u The element has no stable isotopes. However, it has a characteristic terrestrial isotopic composition and thus an atomic mass can be given.Isotopes of protactinium occurring within the… …
123Isotopes of thorium — Although thorium (Th) has multiple isotopes, none of these isotopes are stable; however, one isotope is relatively stable (232Th). As such, thorium is considered to be mononuclidic. It has a characteristic terrestrial isotopic composition and… …
124Isotopes of actinium — Actinium (Ac) has no stable isotopes. A standard atomic mass cannot be given.An isotope of actinium occurring within the radioactive disintegration chain of thorium was known as: * mesothorium II : 228AcNaturally occurring actinium is composed of …
125Isotopes of radium — Radium (Ra) has no stable isotopes. A standard atomic mass cannot be given. The longest lived, and most common, isotope of radium is 226Ra with a half life of 1600 years. 226Ra occurs in the disintegration chain of 238U (often referred to as the… …
126Isotopes of francium — Francium (Fr) has no stable isotopes. A standard atomic mass cannot be given.An isotope of francium occurring within the radioactive disintegration chain of actinium was known as: * actinium K : 223Fr Table Notes * Values marked # are not purely… …
127Isotopes of radon — There are thirty four known isotopes of radon (Rn). The most stable isotope is 222Rn, which is a decay product (daughter product) of 226Ra, has a half life of 3.823 days and emits alpha particles. 220Rn is a natural decay product of thorium and… …
128Isotopes of astatine — Astatine (At) has 33 known isotopes, all of which are radioactive; the range of their mass numbers is from 191 to 223. There exist also 23 metastable excited states. The longest lived isotope is 210At, which has a half life of 8.3 hours; the… …
