List of nuclides

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This list of nuclides shows observed nuclides that either are stable or, if radioactive, have half-lives longer than one hour. This includes isotopes of the first 105 elements, except for 87 (francium), 102 (nobelium) and 104 (rutherfordium). More than 5,000 nuclides have been experimentally characterized, including isomers, of which this page presently includes 987.

## Contents

* 1 Introduction
* 2 List legend
* 3 Full list
* 3.1 Theoretically stable nuclides
* 3.2 Observationally stable nuclides having theoretical decay modes other than spontaneous fission (no lower bounds)
* 3.3 Observationally stable nuclides having theoretical decay modes other than spontaneous fission, for which those decays have experimental lower bounds
* 3.4 Primordial radioactive nuclides (half-life > 108 years)
* 3.5 Radionuclides with half-lives of 104 years to 108 years
* 3.6 Radionuclides with half-lives of 10 years to 104 years
* 3.7 Radionuclide with unknown half-life
* 3.8 Radionuclides with half-lives of 1 day to 10 years
* 3.9 Radionuclides with half-lives of 1 hour to 1 day
* 4 Radionuclides with half-lives less than 1 hour
* 5 See also
* 6 Notes
* 7 References
* 8 External links

## Introduction

Theoretical calculation for the proton and neutron drip lines show that there would be about 7,000 nuclides that are between the drip lines, and containing 2 to 120 protons.[1]

There are presently 251 known stable nuclides. Many of these in theory could decay through spontaneous fission, alpha decay, double beta decay, etc. with a very long half-life, but this has not yet been observed. Thus, the number of stable nuclides is subject to change if some of these 251 have radioactive decay observed in the future. In this article, the "stable" nuclides are divided into three tables: one for nuclides that are theoretically stable (meaning no decay mode is possible) except to spontaneous fission, which is not considered plausible in this mass range; one for nuclides that can theoretically undergo forms of decay other than spontaneous fission but have no published lower bound on lifetime from experimental evaluations; and one for nuclides that can theoretically decay and have been examined without detecting any decay, allowing a lower bound to be published. In this last table, where a decay has been predicted theoretically but never observed experimentally (either directly or by finding an excess of the daughter), the theoretical decay mode is given in parentheses, and "> (lifetime in years)" is shown in the half-life column to show this lower limit in scientific notation. Such nuclides are considered to be "stable", also called "observationally stable" indicating the tentative nature of the conclusion, until some decay has been observed. For example, tellurium-123 was reported to be radioactive, but the same experimental group later retracted this report, and it is again listed as stable.

The next group is the primordial radioactive nuclides. These have been measured to be radioactive, or decay products have been identified in natural samples (tellurium-128, barium-130). There are 35 of these (see these nuclides), of which 25 have half-lives longer than 1013 years. For most of these 25, decay is difficult to observe, and for most purposes they can be regarded as effectively stable. Bismuth-209 is notable as it is the only naturally occurring isotope of an element long considered stable. The other 10, platinum-190, samarium-147, lanthanum-138, rubidium-87, rhenium-187, lutetium-176, thorium-232, uranium-238, potassium-40, and uranium-235, have half-lives between 7×108 and 5×1011 years, which means they have undergone at least 0.5% depletion since the formation of the Solar System about 4.6×109 years ago, but still exist on Earth in significant quantities. They are the primary source of radiogenic heating and radioactive decay products. Together, there are a total of 286 primordial nuclides.[lower-alpha 1]

The list then covers the other radionuclides with half-lives longer than 1 hour, split into several tables in order of successively shorter lifetimes.

Some nuclides that have half-lives too short to be primordial can be detected in nature as a result of later production by natural processes, mostly in trace amounts. These include radionuclides occurring in the decay chains of primordial uranium and thorium (radiogenic nuclides), such as radon-222. Others are the products of interactions with energetic cosmic rays (the cosmogenic nuclides), such as carbon-14. This gives a total of about 350 naturally occurring nuclides, some of which are difficult to detect. Other nuclides may be occasionally produced naturally by rare cosmogenic interactions or as a result of other natural nuclear reactions (nucleogenic nuclides), and these are generally even less detectable.

Non-primordial nuclides may also be detected in the spectra of stars; technetium is well established,[3] and others have been claimed. The remaining nuclides are known solely from artificial nuclear transmutations. Some, such as caesium-137 and krypton-85, are detected in the environment, but only (or practically only) from deliberate or accidental release of artificial production, as fission products (from nuclear weapons or nuclear reactors), for industrial or medical uses, or otherwise.

## List legend

Each group of radionuclides, starting with the longest-lived primordial radionuclides, is sorted by decreasing half-life, but the tables are sortable by other columns. All columns sort by usual lexicographical order; in the case of the nuclide column this gives order on the mass number A.

No. (number) column
A running positive integer for reference, equal to the position in the tables. This number may change in the future, especially for nuclides with short lives, as better half-life estimates become available.
Nuclide column
Nuclide identifiers are given by their atomic mass number A and the symbol for the corresponding chemical element (corresponding to the unique proton number). In the cases that this is not the ground state, this is indicated by a m for metastable appended to the mass number; the conventional numbers are further appended to distinguish multiple metastable states but '1' is omitted if the others are much less stable.
A, Z, N columns
The total number of protons and neutrons together (A) and the separate numbers of protons (Z) and of neutrons (N).
Energy column
The column labeled "energy" denotes the energy equivalent of (the mass of a neutron minus the mass per nucleon), that is of the mass defect with respect to the neutron, in MeV. Use of the neutron as reference guarantees all nuclides will have a positive value. Mathematically: mn − mnuclide / A. Note that this means that a higher "energy" value actually means that the nuclide has a lower energy. Inversely the mass is A (mn − E / k) where E is the energy, mn is 1.0086649159 and k = 931.4941037 MeV (energy equivalent of the dalton). Omitted if there is no experimental mass determination within 0.0001.
Half-life column
The first column shows times in seconds; the second column in the more usual units (years, days, hours). As the first column is converted from the second, it is given enough digits to ensure consistent sorting.
Entries starting with a ">" indicates that no decay has ever been observed, with experiments having established lower limits on the half-life. Such elements are considered stable unless decay is observed (establishing an actual estimate for the half-life). Half-lives are imprecise estimates and may be subject to significant revision. When shown to a smaller than usual number of significant figures, it is not known accurately enough to justify more.
Decay mode column

α  | α decay

|

β− | β− decay
β−β− | double β− decay
ε  | electron capture
β+ | β+ decay
β+β+ | double β+ decay
SF  | spontaneous fission
IT  | isomeric transition
Decay modes in parentheses are given for observationally stable nuclides (these and these); they are then those allowed to occur by energy (in the next column), but spontaneous fission (and cluster decay, which is never shown in the tables) are neglected as they should never be observed for these nuclides. Those with multiple significant decay modes have the probability of each decay mode in percent given, in small figures, in parentheses; those less than 0.05% are rounded to zero and omitted, and 100 (>99.5% of observed decays) is not used but replaced by bold unless the only other decays are SF or double beta, assumed to be minority decays if not listed first. If more than one of α, β−, β+/ε, IT is given without numbers or bold, one can assume no experimental data is available. Note that, by widely used convention, β+ (technically positron emission) includes ε, and conversely, if positron emission is energetically possible; the two are never separated on this page.
Decay energy column
Multiple values for decay energy for each given decay mode (skipping SF), in respective order. Decay energies are the whole energy difference to the ground state of the product, and so include energy lost to neutrinos. Further decays in a decay chain are not included.
Notes column

Cosmogenic nuclide.

Naturally occurring decay product (of thorium-232, uranium-238, or uranium-235), including products of neutron reactions other than fission.
ESS
Present in the early Solar System (first few million years), but extinct now as a primordial nuclide. Inherently overlaps with cosmogenic nuclides.

Nuclear fission product ,[lower-alpha 2] may occur naturally from spontaneous fission.

Industry or medically used radionuclide.[4]

* * *

Of the 701 non-primordial nuclides in the tables below, 101 have the label FP (99 true fission products), 65 IM, 32 DP, 24 CG, 13 ESS, and 7 both CG and ESS.

## Full list

The tables are based now on the standard reference NUBASE2020[5] and its companion, based on the same data, AME2020.[6] All observational data not otherwise cited should be found in those sources, or calculated from them, and only observed data, not theoretical extrapolations, should be present in these tables.

### Theoretically stable nuclides

Main article: Physics:Stable nuclide

These are the theoretically stable nuclides, ordered by "energy".

Template:Row numbers

### Observationally stable nuclides having theoretical decay modes other than spontaneous fission (no lower bounds)

Ordered by "energy".

Template:Row numbers

### Observationally stable nuclides having theoretical decay modes other than spontaneous fission, for which those decays have experimental lower bounds

Ordered by the given lower bound on half-life. These should not be considered authoritative without consulting the original source (footnote, or if none, that given in [5]) as exactly what was measured and how are not reflected here, and some of the values may be misinterpretations. Further, in all cases, this is not an indicator of the probable half-life, which may be much longer (especially for alpha decay), but only the experiment's ability to measure it.

Template:Row numbers

### Primordial radioactive nuclides (half-life > 108 years)

Main article: Chemistry:Primordial nuclide

Ordered by half-life.

Template:Row numbers

### Radionuclides with half-lives of 104 years to 108 years

Ordered by half-life. Some of these are known to have been present in the early Solar System (marked "ESS", meaning the first few million years of the Solar System's history) from an excess of their decay products.[7]

Template:Row numbers

### Radionuclides with half-lives of 10 years to 104 years

Ordered by half-life.

Template:Row numbers

### Radionuclide with unknown half-life

No decay has been observed, but not primordial so does not qualify as "observationally stable".

No. | Nuclide | Z | N | Energy
(MeV) | Half-life
(seconds) | Half-life
(years)[lower-alpha 3] | Decay modes | Notes

|
|
|
|
|
|
|
|

380 | 248Bk | 97 | 151 | 7.7966 | > 2.84×108 | > 9 y[lower-alpha 4] | α, β−, β+ |

### Radionuclides with half-lives of 1 day to 10 years

Ordered by half-life. The second half-life column in this table has been made unsortable, as the mixture of days and years will not sort properly. Resorting by half-life may be done no less by using the number or the half-life in seconds columns.

Template:Row numbers

### Radionuclides with half-lives of 1 hour to 1 day

Ordered by half-life.

Template:Row numbers

## Radionuclides with half-lives less than 1 hour

Main article: Physics:List of radioactive nuclides by half-life

## See also

* Isotope geochemistry
* List of elements by stability of isotopes
* List of radioactive nuclides by half-life
* Monoisotopic element
* Mononuclidic element
* Primordial nuclide
* Radionuclide
* Stable nuclide
* Table of nuclides

## Notes

1. ↑ Two further nuclides, plutonium-244 and samarium-146, have half-lives just long enough (8.13×107 and 9.20×107 years[2]) that they could have survived from the formation of the Solar System and be present on Earth in trace quantities (having survived 56 and 50 half-lives). They might therefore be considered primordial, but fall short of the detection threshold in studies so far.
2. ↑ Two isotopes marked as such, 134Cs and 154Eu, are not directly produced by fission but arise in nuclear reactors by neutron capture on isotopes that are. They are included as they are mentioned elsewhere on Wikipedia as being produced by fission.
3. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `tropical`
4. ↑ Uncertain whether this nuclide is the ground state of its isotope.

## References

1. ↑ Erler, Jochen; Birge, Noah; Kortelainen, Markus; Nazarewicz, Witold; Olsen, Erik; Perhac, Alexander M.; Stoitsov, Mario (June 2012). "The limits of the nuclear landscape" (in en). Nature 486 (7404): 509–512. doi:10.1038/nature11188. ISSN 1476-4687. https://www.nature.com/articles/nature11188.
2. ↑ Chiera, Nadine M.; Sprung, Peter; Amelin, Yuri; Dressler, Rugard; Schumann, Dorothea; Talip, Zeynep (1 August 2024). "The 146Sm half-life re-measured: consolidating the chronometer for events in the early Solar System". Scientific Reports 14 (1): 17436. doi:10.1038/s41598-024-64104-6. PMID 39090187.
3. ↑ Merrill, Paul W. (September 1954). "17. Technetium in S-type stars". Transactions of the International Astronomical Union 8: 832–833. https://www.cambridge.org/core/journals/transactions-of-the-international-astronomical-union/article/17-technetium-in-stype-stars/2BF75C2E03D323ED8A47150912DD595C.
4. ↑ Primarily sourced from [1] and [2]. (accessed 2025-07-18)
5. ↑ 5.0 5.1 Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties". Chinese Physics C 45 (3). doi:10.1088/1674-1137/abddae. https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf.
6. ↑ Template:AME2020 II
7. ↑ Davis, Andrew M. (2022). "Short-Lived Nuclides in the Early Solar System: Abundances, Origins, and Applications". Annual Review of Nuclear and Particle Science 72: 339–363. doi:10.1146/annurev-nucl-010722-074615. Bibcode: 2022ARNPS..72..339D.

## External links

* National Nuclear Data Center, Brookhaven National Laboratory
* IAEA Chart of Nuclides
* National Isotope Development Center Reference information on isotopes, and coordination and management of isotope production, availability, and distribution
* Isotope Development & Production for Research and Applications (IDPRA) U.S. Department of Energy program for isotope production and production research and development
* Accelerator Systems and Stable Isotopes Group at ORNL
* Discovery of Nuclides Project main page, does not (yet) include isomers
* Index to all isotopes
* Index to all isomers

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