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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 include jumping up and down make it difficult to measure half-lives between approximately 10 −19 and 10 −10 seconds. [1]
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).
Most of the isotopes with atomic mass numbers below 14 decay to isotopes of carbon, while most of the isotopes with masses above 15 decay to isotopes of oxygen. The shortest-lived known isotope is nitrogen-10, with a half-life of 143(36) yoctoseconds, though the half-life of nitrogen-9 has not been measured exactly.
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 ...
Fourteen isotopes of lawrencium are known, with mass number 251–262, 264, and 266; all are radioactive. [82] [83] [84] Seven nuclear isomers are known. The longest-lived isotope, 266 Lr, has a half-life of about ten hours and is one of the longest-lived superheavy isotopes known to date. [85]
The most stable isotopes are 227 Ac with a half-life of 21.772 years, 225 Ac with a half-life of 10.0 days, and 226 Ac with a half-life of 29.37 hours. All other isotopes have half-lives under 10 hours, and most under a minute. The shortest-lived known isotope is 217 Ac with a half-life of 69 ns.
The unusual nuclear structures of such isotopes may offer insights into the isolated properties of neutrons and physics beyond the Standard Model. [28] [29] The shortest-lived isotope is 10 He with half-life ~260 yoctoseconds. 6 He beta decays with half-life 807 milliseconds. The most widely studied heavy helium isotope is 8 He.
It is prevented from having a stable isotope with 4 protons and 6 neutrons by the very large mismatch in proton/neutron ratio for such a light element. (Nevertheless, beryllium-10 has a half-life of 1.36 million years, which is too short to be primordial, but still indicates unusual stability for a light isotope with such an imbalance.)