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This is a list of radioactive nuclides (sometimes also called isotopes), ordered by half-life from shortest to longest, in seconds, minutes, hours, days and years. Current methods make it difficult to measure half-lives between approximately 10 −19 and 10 −10 seconds. [1]
This is the longest half-life directly measured for any unstable isotope; [4] only the half-life of tellurium-128 is longer. [ citation needed ] Of the chemical elements, only 1 element ( tin ) has 10 such stable isotopes, 5 have 7 stable isotopes, 7 have 6 stable isotopes, 11 have 5 stable isotopes, 9 have 4 stable isotopes, 5 have 3 stable ...
Considering all decay modes, various models indicate a shift of the center of the island (i.e., the longest-living nuclide) from 298 Fl to a lower atomic number, and competition between alpha decay and spontaneous fission in these nuclides; [83] these include 100-year half-lives for 291 Cn and 293 Cn, [55] [78] a 1000-year half-life for 296 Cn ...
This represents isotopes of the first 105 elements, except for elements 87 , 102 and 104 (rutherfordium). At least 3,300 nuclides have been experimentally characterized [ 1 ] (see List of radioactive nuclides by half-life for the nuclides with decay half-lives less than one hour).
The original term, half-life period, dating to Ernest Rutherford's discovery of the principle in 1907, was shortened to half-life in the early 1950s. [1] Rutherford applied the principle of a radioactive element's half-life in studies of age determination of rocks by measuring the decay period of radium to lead-206.
Bismuth-209 was long thought to have the heaviest stable nucleus of any element, but in 2003, a research team at the Institut d’Astrophysique Spatiale in Orsay, France, discovered that 209 Bi undergoes alpha decay with a half-life of 20.1 exayears (2.01×10 19, or 20.1 quintillion years), [3] [4] over 10 9 times longer than the estimated age of the universe. [5]
Its longest-lived radioactive isotope, 129 I, has a half-life of 16.14 million years, which is far too short for it to exist as a primordial nuclide. Cosmogenic sources of 129 I produce very tiny quantities of it that are too small to affect atomic weight measurements; iodine is thus also a mononuclidic element —one that is found in nature ...
It is an actinide and the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities, although pure fermium metal has not been prepared yet. [5] A total of 20 isotopes are known, with 257 Fm being the longest-lived with a half-life of 100.5 days.