Стабильность изотопов химических элементов

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This is a list of chemical elements by the stability of their isotopes. Of the first 82 elements in the periodic table, 80 have isotopes considered to be stable. Technetium and promethium (atomic numbers 43 and 61, respectively) and all the elements with an atomic number over 82 only have isotopes that are known to decompose through radioactive decay. No undiscovered elements are expected to be stable; therefore, lead is considered the heaviest stable element. However, it is possible that some isotopes that are now considered stable will be revealed to decay with extremely long half lives (as with Bismuth 209). This list depicts what is agreed upon by the consensus of the scientific community as of 2023. only the half life of tellurium 128 is longer. 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 isotopes, 16 have 2 stable isotopes, and 26 have 1 stable isotope. Another notable example is the only naturally occurring isotope of bismuth, bismuth 209, which has been predicted to be unstable with a very long half life, but has been observed to decay. Because of their long half lives, such isotopes are still found on Earth in various quantities, and together with the stable isotopes they are called primordial isotopes. All the primordial isotopes are given in order of their decreasing abundance on Earth. For a list of primordial nuclides in order of half life, see List of nuclides. 118 chemical elements are known to exist. All elements to element 94 are found in nature, and the remainder of the discovered elements are artificially produced, with isotopes all known to be highly radioactive with relatively short half lives (see below). The elements in this list are ordered according to the lifetime of their most stable isotope. Of these, three elements (bismuth, thorium, and uranium) are primordial because they have half lives long enough to still be found on the Earth, while all the others are produced either by radioactive decay or are synthesized in laboratories and nuclear reactors. Only 13 of the 38 known but unstable elements have isotopes with a half life of at least 100 years. Every known isotope of the remaining 25 elements is highly radioactive; these are used in academic research and sometimes in industry and medicine. Some of the heavier elements in the periodic table may be revealed to have yet undiscovered isotopes with longer lifetimes than those listed here. About 338 nuclides are found naturally on Earth. These comprise 251 stable isotopes, and with the addition of the 35 long lived radioisotopes with half lives longer than 100 million years, a total of 286 primordial nuclides, as noted above. The nuclides found naturally comprise not only the 286 primordials, but also include about 52 more short lived isotopes (defined by a half life less than 100 million years, too short to have survived from the formation of the Earth) that are daughters of primordial isotopes (such as radium from uranium); or else are made by energetic natural processes, such as carbon 14 made from atmospheric nitrogen by bombardment from cosmic rays.

An even number of protons or neutrons is more stable (higher binding energy) because of pairing effects, so even–even nuclides are much more stable than odd–odd. One effect is that there are few stable odd–odd nuclides: in fact only five are stable, with another four having half lives longer than a billion years. Another effect is to prevent beta decay of many even–even nuclides into another even–even nuclide of the same mass number but lower energy, because decay proceeding one step at a time would have to pass through an odd–odd nuclide of higher energy. (Double beta decay directly from even–even to even–even, skipping over an odd odd nuclide, is only occasionally possible, and is a process so strongly hindered that it has a half life greater than a billion times the age of the universe.) This makes for a larger number of stable even–even nuclides, up to three for some mass numbers, and up to seven for some atomic (proton) numbers and at least four for all stable even Z elements beyond iron (except strontium and lead). Since a nucleus with an odd number of protons is relatively less stable, odd numbered elements tend to have fewer stable isotopes. Of the 26 "monoisotopic" elements that have only a single stable isotope, all but one have an odd atomic number—the single exception being beryllium. In addition, no odd numbered element has more than two stable isotopes, while every even numbered element with stable isotopes, except for helium, beryllium, and carbon, has at least three. Only a single odd numbered element, potassium, has three primordial isotopes; none have more than three.

+No primordial isotopesLongest lived isotope > 1 day Z Element t1⁄2 Longest livedisotope 94 plutonium 8.08 Plutonium 244 96 curium 1.56 Curium 247 43 technetium 4.21 Technetium 97 93 neptunium 2.14 Neptunium 237 91 protactinium 32,760 yr Protactinium 231 95 americium 7,370 yr Americium 243 88 radium 1,600 yr Radium 226 97 berkelium 1,380 yr Berkelium 247 98 californium 900 yr Californium 251 84 polonium 125 yr Polonium 209 89 actinium 21.772 yr Actinium 227 61 promethium 17.7 yr Promethium 145 99 einsteinium 1.293 yr Einsteinium 252100 fermium 100.5 d Fermium 257101 mendelevium 51.3 d Mendelevium 258 86 radon 3.823 d Radon 222+No primordial isotopesLongest lived isotope < 1 day Z Element t1⁄2 Longest livedisotope105 dubnium 16 h Dubnium 268103 lawrencium 11 h Lawrencium 266 85 astatine 8.1 h Astatine 210102 nobelium 58 min Nobelium 259104 rutherfordium 48 min Rutherfordium 267 87 francium 22 min Francium 223106 seaborgium 14 min Seaborgium 269107 bohrium 2.4 min Bohrium 270111 roentgenium 1.7 min Roentgenium 282112 copernicium 28 s Copernicium 285108 hassium 16 s Hassium 269110 darmstadtium 12.7 s Darmstadtium 281113 nihonium 9.5 s Nihonium 286109 meitnerium 4.5 s Meitnerium 278114 flerovium 1.9 s Flerovium 289115 moscovium 650 ms Moscovium 290116 livermorium 57 ms Livermorium 293117 tennessine 51 ms Tennessine 294118 oganesson 690 μs Oganesson 294