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The longest-lived radioisotopes are 205 Pb with a half-life of 17.3 million years and 202 Pb with a half-life of 52,500 years. A shorter-lived naturally occurring radioisotope, 210 Pb with a half-life of 22.2 years, is useful for studying the sedimentation chronology of environmental samples on time scales shorter than 100 years. [5]
Lead-210 is particularly useful for helping to identify the ages of samples by measuring its ratio to lead-206 (both isotopes are present in a single decay chain). [51] In total, 43 lead isotopes have been synthesized, with mass numbers 178–220. [38] Lead-205 is the most stable radioisotope, with a half-life of around 1.70 × 10 7 years.
Isotopes of polonium (84Po) There are 42 isotopes of polonium (84 Po). They range in size from 186 to 227 nucleons. They are all radioactive. 210 Po with a half-life of 138.376 days has the longest half-life of any naturally-occurring isotope of polonium and is the most common isotope of polonium. It is also the most easily synthesized polonium ...
Polonium-210. Polonium-210 (210 Po, Po-210, historically radium F) is an isotope of polonium. It undergoes alpha decay to stable 206 Pb with a half-life of 138.376 days (about 4⁄ months), the longest half-life of all naturally occurring polonium isotopes (210–218 Po). [1] First identified in 1898, and also marking the discovery of the ...
Radioactive isotope table "lists ALL radioactive nuclei with a half-life greater than 1000 years", incorporated in the list above. The NUBASE2020 evaluation of nuclear physics properties F.G. Kondev et al. 2021 Chinese Phys. C 45 030001. The PDF of this article lists the half-lives of all known radioactives nuclides.
210 Po is an alpha emitter that has a half-life of 138.4 days; it decays directly to its stable daughter isotope, 206 Pb. A milligram (5 curies ) of 210 Po emits about as many alpha particles per second as 5 grams of 226 Ra , [ 6 ] which means it is 5,000 times more radioactive than radium.
One of the primordial nuclides is tantalum-180m, which is predicted to have a half-life in excess of 10 15 years, but has never been observed to decay. The even-longer half-life of 2.2 × 10 24 years of tellurium-128 was measured by a unique method of detecting its radiogenic daughter xenon-128 and is the longest known experimentally measured ...
Precise Pb–Pb dating of meteorites. References. Lead–lead dating. Appearance. Lead–lead dating is a method for dating geological samples, normally based on 'whole-rock' samples of material such as granite. For most dating requirements it has been superseded by uranium–lead dating (U–Pb dating), but in certain specialized situations ...