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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 list of nuclides shows observed nuclides that either are stable or, if radioactive, have half-lives longer than one hour. This represents isotopes of the first 105 elements, except for elements 87 ( francium ), 102 ( nobelium ) and 104 ( rutherfordium ).
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 ...
Carbon (6 C) has 14 known isotopes, from 8 C to 20 C as well as 22 C, of which 12 C and 13 C are stable.The longest-lived radioisotope is 14 C, with a half-life of 5.70(3) × 10 3 years. . This is also the only carbon radioisotope found in nature, as trace quantities are formed cosmogenically by the reactio
Half-life (symbol t ½) is the time required for a quantity (of substance) to reduce to half of its initial value.The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable atoms survive.
All three isotopes are radioactive (i.e., they are radioisotopes), and the most abundant and stable is uranium-238, with a half-life of 4.4683 × 10 9 years (about the age of the Earth). Uranium-238 is an alpha emitter , decaying through the 18-member uranium series into lead-206 .
(The more massive 209 Bi, long considered to be stable, actually has a half-life of 2.01×10 19 years.) 208 Pb is also a doubly magic isotope, as it has 82 protons and 126 neutrons. [6] It is the heaviest doubly magic nuclide known. A total of 43 lead isotopes are now known, including very unstable synthetic species.
Iron-60 is an iron isotope with a half-life of 2.6 million years, [12] [13] but was thought until 2009 to have a half-life of 1.5 million years. It undergoes beta decay to cobalt-60, which then decays with a half-life of about 5 years to stable nickel-60. Traces of iron-60 have been found in lunar samples.