View source for List of elements by stability of isotopes

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[[File:Isotopes and half-life.svg|right|thumb|300px|[[Isotope]] half-lives. The darker more stable isotope region departs from the line of protons (Z) = neutrons (N), as the element number Z becomes larger.]]

Of the first 82 [[chemical elements]] in the [[periodic table]], 80 have [[isotope]]s considered to be stable.<ref name="nuclidetable" /> Overall, there are 251 known stable isotopes in total.

== Background ==
[[Atomic nucleus|Atomic nuclei]] consist of [[proton]]s and [[neutron]]s, which attract each other through the [[nuclear force]], while protons repel each other via the [[electric force]] due to their positive [[charge (physics)|charge]]. These two forces compete, leading to some combinations of neutrons and protons being more stable than others. Neutrons stabilize the nucleus, because they attract protons, which helps offset the electrical repulsion between protons. As a result, as the number of protons increases, an increasing [[neutron–proton ratio|ratio of neutrons to protons]] is needed to form a stable nucleus; if too many or too few neutrons are present with regard to the optimum ratio, the nucleus becomes unstable and subject to certain types of [[nuclear decay]]. Unstable [[isotope]]s decay through various [[radioactive decay|radioactive decay pathways]], most commonly [[alpha decay]] or [[beta decay]], but rarer types of decay including [[spontaneous fission]] and [[cluster decay]] are known; more detail can be found at [[radioactive decay]].

Of the first 82 elements in the [[periodic table]], 80 have [[isotope]]s considered to be stable.<ref name=nuclidetable/> The 83rd element, bismuth, was traditionally regarded as having the heaviest stable isotope, [[bismuth-209]], but in 2003 researchers in [[Orsay]], France, measured the decay of {{SimpleNuclide|Bismuth|209|link=yes}}<ref>{{cite journal|last= Marcillac|first= Pierre de |author2= Noël Coron |author3= Gérard Dambier |author4= Jacques Leblanc |author5= Jean-Pierre Moalic |name-list-style= amp|date=2003|title= Experimental detection of α-particles from the radioactive decay of natural bismuth|journal= Nature|volume= 422|pages= 876–878|pmid=12712201|doi= 10.1038/nature01541|issue= 6934 |bibcode= 2003Natur.422..876D|s2cid= 4415582 }}</ref><ref>{{cite news|url=https://physicsworld.com/a/bismuth-breaks-half-life-record-for-alpha-decay/|title=Bismuth breaks half-life record for alpha decay|last=Dumé|first=Belle|date=2003-04-23|publisher=[[Institute of Physics]] Publishing}}</ref>; the currently accepted [[half-life]] is {{val|2.01|e=19|u=years}}. [[Technetium]] and [[promethium]] ([[atomic number]]s 43 and 61, respectively{{efn|name=Note1}}) and all the elements with an atomic number over 82 only have isotopes that are known to undergo [[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 happened with bismuth).

For each of the 80 stable elements, the number of stable isotopes is given. Only 90 isotopes are stable against any possible decay, and an additional 161 are energetically unstable (see [[List of nuclides]]) but have never been observed to decay. Thus, 251 isotopes ([[nuclide]]s) are [[stable nuclide|stable]] by definition (including an excited state, tantalum-180m, for which no decay has yet been observed).

In April 2019 it was announced that the half-life of xenon-124 had been measured to 1.8 × 10<sup>22</sup> years.<ref>{{cite web|url=https://www.forbes.com/sites/startswithabang/2019/04/24/dark-matter-search-discovers-a-spectacular-bonus-the-longest-lived-unstable-element-ever/|title=Dark Matter Search Discovers A Spectacular Bonus: The Longest-Lived Unstable Element Ever|last=Siegel|first=Ethan|website=Forbes|language=en|access-date=2019-04-25}}</ref> This is the longest half-life directly measured for any unstable isotope; only the (indirectly measured) 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.<ref name=nuclidetable/>

Additionally, 31 nuclides of the naturally occurring elements have unstable isotopes with a half-life long enough to have survived for the age of the [[Solar System]] (10<sup>8</sup> years or more), and an additional four such nuclides represent three elements ([[bismuth]], [[thorium]], [[uranium]]) having no stable isotope. These 35 radioactive naturally occurring nuclides comprise the radioactive [[primordial nuclide]]s. The total number of primordial nuclides is then 251 (the stable nuclides) plus the 35 radioactive primordial nuclides, for a total of 286.

The longest known half-life of 2.2 × 10<sup>24</sup> years of [[tellurium-128]] was measured by the method of detecting its radiogenic daughter [[xenon-128]]; this has been used for other isotopes with noble-gas daughters and [[barium-130]] has also been measured no other way.<ref>{{cite web|url=http://presolar.wustl.edu/work/noblegas.html |title=Noble Gas Research |access-date=2013-01-10 |url-status=dead |archive-url=https://web.archive.org/web/20110928143717/http://presolar.wustl.edu/work/noblegas.html |archive-date=2011-09-28}} Novel Gas Research. Accessed April 26, 2009</ref> 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 element|primordial isotopes]]. For a list of primordial nuclides in order of half-life, see [[List of nuclides]].

118 [[chemical elements]] are known to exist. The first 94 are found in nature, and the remainder of the [[list of chemical elements by their discovery|discovered elements]] are artificially produced, with isotopes all known to be [[radioactive isotope|radioactive]] with relatively short half-lives (see below). The elements in this list are ordered according to the lifetime of their most stable isotope.<ref name="nuclidetable">{{cite web|url=https://www.nndc.bnl.gov/nudat3/|title=Interactive Chart of Nuclides|author=Sonzogni, Alejandro|publisher=Brookhaven National Laboratory|location=National Nuclear Data Center|access-date=2019-08-30}}</ref> Of these, three elements ([[bismuth]], [[thorium]], and [[uranium]]) are primordial because they have half-lives long enough to still be found on the Earth,{{efn|name=Note3}} while all the others are produced either by [[radioactive decay]] or are [[synthetic element|synthesized]] in laboratories and [[nuclear reactor]]s. Only 13 of the 38 unstable elements have a known isotope 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.{{efn|name=Note4}} Some of the heavier elements in the periodic table may be revealed to have yet-undiscovered isotopes with longer lifetimes than those listed here.{{efn|name=Note5}}

About 338 nuclides are found naturally on Earth. These comprise not only the 286 primordials, but also include about 52 shorter-lived isotopes that either are daughters of primordial isotopes (such as [[radium]] from [[uranium]]) or are made by energetic natural processes, such as [[carbon-14]] made from atmospheric nitrogen by bombardment from [[cosmic ray]]s.

==Elements by number of primordial isotopes==
An [[even and odd atomic nuclei|even number of protons or neutrons]] is more stable (higher [[binding energy]]) because of [[semi-empirical mass formula#Pairing term|pairing effects]], so even–even [[nuclide]]s 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 possible, but is so strongly hindered that known cases have [[half-lives]] greater than 10<sup>8</sup> times the [[age of the universe]].) This makes for a larger number of stable even–even nuclides, [[beta-decay stable isobars|up to three for some mass numbers]], up to seven for some atomic (proton) numbers, with at least four for all stable even-''Z'' elements beyond [[argon]].

Since nuclei with odd numbers of protons are relatively less stable, odd-numbered elements tend to have fewer stable isotopes. Of the 26 [[monoisotopic element|monoisotopic]] elements (those with exactly one 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 heavier than carbon with stable isotopes has at least three. Only a single odd-numbered element, [[potassium]], has three primordial isotopes and none more than that.

==Tables==
The following tables give the elements with [[primordial nuclide]]s (half-life of most stable isotope > 10<sup>8</sup> years). A list of nuclides sorted by half-life is found instead at [[List of nuclides]].

The tables of elements are sorted by decreasing number of nuclides per element. Stable and unstable nuclides are given, with symbols for the unstable ones in italics. All the primordial isotopes of each element are given in order of decreasing [[abundance of the chemical elements|abundance on Earth]], regardless of stability.{{efn|name=Note2}} By convention, nuclides are counted as "stable" if they have never been observed to decay by experiment or from observation of decay products (so that nuclides unstable in theory, such as tantalum-180m, are counted as stable).

The first table is for [[even and odd atomic nuclei|even-atomic numbered]] elements, which tend to have far more primordial nuclides, due to the stability conferred by proton pairing. A second separate table is given for odd-atomic numbered elements, which tend to have far fewer stable and long-lived nuclides.

<div style="float: left; margin: 5px;">
{|class="sortable wikitable" align="top" style="text-align:center"
|+Primordial isotopes (in order of decreasing abundance on Earth{{efn|name=Note2}}) of even-Z elements
|-
! Z<br>
! Element<br>
! <small>[[Stable nuclide|Stable]]</small><br><ref name=nuclidetable/>
! <small>''[[Primordial element|Decays]]''<br><ref name=nuclidetable/></small>
! class="unsortable" colspan="10"|<small>'''unstable in bold'''<div style="background:pink">odd [[neutron number]] in pink</div></small>
|-
| 50 ||[[tin]]          || [[isotopes of tin|10]]       || —
|{{SimpleNuclide|tin|120}}||{{SimpleNuclide|tin|118}}||{{SimpleNuclide|tin|116}}||bgcolor="pink"|{{SimpleNuclide|tin|119}}||bgcolor="pink"|{{SimpleNuclide|tin|117}}||{{SimpleNuclide|tin|124}}||{{SimpleNuclide|tin|122}}||{{SimpleNuclide|tin|112}}||{{SimpleNuclide|tin|114}}||bgcolor="pink"|{{SimpleNuclide|tin|115}}
|-
| 54 ||[[xenon]]        || [[isotopes of xenon|7]]      || 2
|{{SimpleNuclide|xenon|132}}||bgcolor="pink"|{{SimpleNuclide|xenon|129}}||bgcolor="pink"|{{SimpleNuclide|xenon|131}}||{{SimpleNuclide|xenon|134}}||'''{{SimpleNuclide|xenon|136}}'''||{{SimpleNuclide|xenon|130}}||{{SimpleNuclide|xenon|128}}||'''{{SimpleNuclide|xenon|124}}'''||{{SimpleNuclide|xenon|126}}
|-
| 48 ||[[cadmium]]      || [[isotopes of cadmium|6]]    || 2
|{{SimpleNuclide|cadmium|114}}||{{SimpleNuclide|cadmium|112}}||bgcolor="pink"|{{SimpleNuclide|cadmium|111}}||{{SimpleNuclide|cadmium|110}}||bgcolor="pink"|'''{{SimpleNuclide|cadmium|113}}'''||'''{{SimpleNuclide|cadmium|116}}'''||{{SimpleNuclide|cadmium|106}}||{{SimpleNuclide|cadmium|108}}
|-
| 52 ||[[tellurium]]    || [[isotopes of tellurium|6]]  || 2
|'''{{SimpleNuclide|tellurium|130}}'''||'''{{SimpleNuclide|tellurium|128}}'''||{{SimpleNuclide|tellurium|126}}||bgcolor="pink"|{{SimpleNuclide|tellurium|125}}||{{SimpleNuclide|tellurium|124}}||{{SimpleNuclide|tellurium|122}}||bgcolor="pink"|{{SimpleNuclide|tellurium|123}}||{{SimpleNuclide|tellurium|120}}
|-
| 44 ||[[ruthenium]]    || [[isotopes of ruthenium|7]]  || —
|{{SimpleNuclide|ruthenium|102}}||{{SimpleNuclide|ruthenium|104}}||bgcolor="pink"|{{SimpleNuclide|ruthenium|101}}||bgcolor="pink"|{{SimpleNuclide|ruthenium|99}}||{{SimpleNuclide|ruthenium|100}}||{{SimpleNuclide|ruthenium|96}}||{{SimpleNuclide|ruthenium|98}}
|-
| 66 ||[[dysprosium]]   || [[isotopes of dysprosium|7]] || —
|{{SimpleNuclide|dysprosium|164}}||{{SimpleNuclide|dysprosium|162}}||bgcolor="pink"|{{SimpleNuclide|dysprosium|163}}||bgcolor="pink"|{{SimpleNuclide|dysprosium|161}}||{{SimpleNuclide|dysprosium|160}}||{{SimpleNuclide|dysprosium|158}}||{{SimpleNuclide|dysprosium|156}}
|-
| 70 ||[[ytterbium]]    || [[isotopes of ytterbium|7]]  || —
|{{SimpleNuclide|ytterbium|174}}||{{SimpleNuclide|ytterbium|172}}||bgcolor="pink"|{{SimpleNuclide|ytterbium|173}}||bgcolor="pink"|{{SimpleNuclide|ytterbium|171}}||{{SimpleNuclide|ytterbium|176}}||{{SimpleNuclide|ytterbium|170}}||{{SimpleNuclide|ytterbium|168}}
|-
| 80 ||[[mercury (element)|mercury]] || [[isotopes of mercury|7]] ||—
|{{SimpleNuclide|mercury|202}}||{{SimpleNuclide|mercury|200}}||bgcolor="pink"|{{SimpleNuclide|mercury|199}}||bgcolor="pink"|{{SimpleNuclide|mercury|201}}||{{SimpleNuclide|mercury|198}}||{{SimpleNuclide|mercury|204}}||{{SimpleNuclide|mercury|196}}
|-
| 42 ||[[molybdenum]]   || [[isotopes of molybdenum|6]] || 1
| {{SimpleNuclide|molybdenum|98}}||{{SimpleNuclide|molybdenum|96}}||bgcolor="pink"|{{SimpleNuclide|molybdenum|95}}||{{SimpleNuclide|molybdenum|92}}||'''{{SimpleNuclide|molybdenum|100}}'''||bgcolor="pink"|{{SimpleNuclide|molybdenum|97}}||{{SimpleNuclide|molybdenum|94}}
|-
| 56 ||[[barium]]       || [[isotopes of barium|6]]     || 1
|{{SimpleNuclide|barium|138}}||bgcolor="pink"|{{SimpleNuclide|barium|137}}||{{SimpleNuclide|barium|136}}||bgcolor="pink"|{{SimpleNuclide|barium|135}}||{{SimpleNuclide|barium|134}}||{{SimpleNuclide|barium|132}}||'''{{SimpleNuclide|barium|130}}'''
|-
| 64 ||[[gadolinium]]   || [[isotopes of gadolinium|6]] || 1
| {{SimpleNuclide|gadolinium|158}}||{{SimpleNuclide|gadolinium|160}}||{{SimpleNuclide|gadolinium|156}}||bgcolor="pink"|{{SimpleNuclide|gadolinium|157}}||bgcolor="pink"|{{SimpleNuclide|gadolinium|155}}||{{SimpleNuclide|gadolinium|154}}||'''{{SimpleNuclide|gadolinium|152}}'''
|-
| 60 ||[[neodymium]]    || [[isotopes of neodymium|5]]  || 2
|{{SimpleNuclide|neodymium|142}}||'''{{SimpleNuclide|neodymium|144}}'''||{{SimpleNuclide|neodymium|146}}||bgcolor="pink"|{{SimpleNuclide|neodymium|143}}||bgcolor="pink"|{{SimpleNuclide|neodymium|145}}||{{SimpleNuclide|neodymium|148}}||'''{{SimpleNuclide|neodymium|150}}'''
|-
| 62 ||[[samarium]]     || [[isotopes of samarium|5]]   || 2
|{{SimpleNuclide|samarium|152}}||{{SimpleNuclide|samarium|154}}||bgcolor="pink"|'''{{SimpleNuclide|samarium|147}}'''||bgcolor="pink"|{{SimpleNuclide|samarium|149}}||'''{{SimpleNuclide|samarium|148}}'''||{{SimpleNuclide|samarium|150}}||{{SimpleNuclide|samarium|144}}
|-
| 76 ||[[osmium]]       || [[isotopes of osmium|5]]     || 2
| {{SimpleNuclide|osmium|192}}||{{SimpleNuclide|osmium|190}}||bgcolor="pink"|{{SimpleNuclide|osmium|189}}||{{SimpleNuclide|osmium|188}}||bgcolor="pink"|{{SimpleNuclide|osmium|187}}||'''{{SimpleNuclide|osmium|186}}'''||'''{{SimpleNuclide|osmium|184}}'''
|-
| 46 ||[[palladium]]    || [[isotopes of palladium|6]]  || —
| {{SimpleNuclide|palladium|106}}||{{SimpleNuclide|palladium|108}}||bgcolor="pink"|{{SimpleNuclide|palladium|105}}||{{SimpleNuclide|palladium|110}}||{{SimpleNuclide|palladium|104}}||{{SimpleNuclide|palladium|102}}
|-
| 68 ||[[erbium]]       || [[isotopes of erbium|6]]     || —
| {{SimpleNuclide|erbium|166}}||{{SimpleNuclide|erbium|168}}||bgcolor="pink"|{{SimpleNuclide|erbium|167}}||{{SimpleNuclide|erbium|170}}||{{SimpleNuclide|erbium|164}}||{{SimpleNuclide|erbium|162}}
|-
| 20 ||[[calcium]]      || [[isotopes of calcium|5]]    || 1
| {{SimpleNuclide|calcium|40}}||{{SimpleNuclide|calcium|44}}||{{SimpleNuclide|calcium|42}}||'''{{SimpleNuclide|calcium|48|link=yes}}'''||bgcolor="pink"|{{SimpleNuclide|calcium|43}}||{{SimpleNuclide|calcium|46}}
|-
| 34 ||[[selenium]]     || [[isotopes of selenium|5]]   || 1
| {{SimpleNuclide|selenium|80}}||{{SimpleNuclide|selenium|78}}||{{SimpleNuclide|selenium|76}}||'''{{SimpleNuclide|selenium|82}}'''||bgcolor="pink"|{{SimpleNuclide|selenium|77}}||{{SimpleNuclide|selenium|74}}
|-
| 36 ||[[krypton]]      || [[isotopes of krypton|5]]    || 1
| {{SimpleNuclide|krypton|84}}||{{SimpleNuclide|krypton|86}}||{{SimpleNuclide|krypton|82}}||bgcolor="pink"|{{SimpleNuclide|krypton|83}}||{{SimpleNuclide|krypton|80}}||'''{{SimpleNuclide|krypton|78}}'''
|-
| 72 ||[[hafnium]]      || [[isotopes of hafnium|5]]    || 1
| {{SimpleNuclide|hafnium|180}}||{{SimpleNuclide|hafnium|178}}||bgcolor="pink"|{{SimpleNuclide|hafnium|177}}||bgcolor="pink"|{{SimpleNuclide|hafnium|179}}||{{SimpleNuclide|hafnium|176}}||'''{{SimpleNuclide|hafnium|174}}'''
|-
| 78 ||[[platinum]]     || [[isotopes of platinum|5]]   || 1
|bgcolor="pink"|{{SimpleNuclide|platinum|195}}||{{SimpleNuclide|platinum|194}}||{{SimpleNuclide|platinum|196}}||{{SimpleNuclide|platinum|198}}||{{SimpleNuclide|platinum|192}}||'''{{SimpleNuclide|platinum|190}}'''
|-
| 22 ||[[titanium]]     || [[isotopes of titanium|5]]   || —
| {{SimpleNuclide|titanium|48}}||{{SimpleNuclide|titanium|46}}||bgcolor="pink"|{{SimpleNuclide|titanium|47}}||bgcolor="pink"|{{SimpleNuclide|titanium|49}}||{{SimpleNuclide|titanium|50}}
|-
| 28 ||[[nickel]]       || [[isotopes of nickel|5]]     || —
| {{SimpleNuclide|nickel|58}}||{{SimpleNuclide|nickel|60}}||{{SimpleNuclide|nickel|62|link=yes}}||bgcolor="pink"|{{SimpleNuclide|nickel|61}}||{{SimpleNuclide|nickel|64}}
|-
| 30 ||[[zinc]]         || [[isotopes of zinc|5]]       || —
| {{SimpleNuclide|zinc|64}}||{{SimpleNuclide|zinc|66}}||{{SimpleNuclide|zinc|68}}||bgcolor="pink"|{{SimpleNuclide|zinc|67}}||{{SimpleNuclide|zinc|70}}
|-
| 32 ||[[germanium]]    || [[isotopes of germanium|4]]  || 1
| {{SimpleNuclide|germanium|74}}||{{SimpleNuclide|germanium|72}}||{{SimpleNuclide|germanium|70}}||bgcolor="pink"|{{SimpleNuclide|germanium|73}}||'''{{SimpleNuclide|germanium|76}}'''
|-
| 40 ||[[zirconium]]    || [[isotopes of zirconium|4]]  || 1
| {{SimpleNuclide|zirconium|90}}||{{SimpleNuclide|zirconium|94}}||{{SimpleNuclide|zirconium|92}}||bgcolor="pink"|{{SimpleNuclide|zirconium|91}}||'''{{SimpleNuclide|zirconium|96}}'''
|-
| 74 ||[[tungsten]]     || [[isotopes of tungsten|4]]   || 1
| {{SimpleNuclide|tungsten|184}}||{{SimpleNuclide|tungsten|186}}||{{SimpleNuclide|tungsten|182}}||bgcolor="pink"|{{SimpleNuclide|tungsten|183}}||'''{{SimpleNuclide|tungsten|180}}'''
|-
| 16 ||[[sulfur]]       || [[isotopes of sulfur|4]]     || —
| {{SimpleNuclide|sulfur|32}}||{{SimpleNuclide|sulfur|34}}||bgcolor="pink"|{{SimpleNuclide|sulfur|33}}||{{SimpleNuclide|sulfur|36}}
|-
| 24 ||[[chromium]]     || [[isotopes of chromium|4]]   || —
| {{SimpleNuclide|chromium|52}}||bgcolor="pink"|{{SimpleNuclide|chromium|53}}||{{SimpleNuclide|chromium|50}}||{{SimpleNuclide|chromium|54}}
|-
| 26 ||[[iron]]         || [[isotopes of iron|4]]       || —
| {{SimpleNuclide|iron|56|link=yes}}||{{SimpleNuclide|iron|54}}||bgcolor="pink"|{{SimpleNuclide|iron|57}}||{{SimpleNuclide|iron|58}}
|-
| 38 ||[[strontium]]    || [[isotopes of strontium|4]]  || —
| {{SimpleNuclide|strontium|88}}||{{SimpleNuclide|strontium|86}}||bgcolor="pink"|{{SimpleNuclide|strontium|87}}||{{SimpleNuclide|strontium|84}}
|-
| 58 ||[[cerium]]       || [[isotopes of cerium|4]]     || —
| {{SimpleNuclide|cerium|140}}||{{SimpleNuclide|cerium|142}}||{{SimpleNuclide|cerium|138}}||{{SimpleNuclide|cerium|136}}
|-
| 82 ||[[lead]]         || [[isotopes of lead|4]]       || —
| {{SimpleNuclide|lead|208}}||{{SimpleNuclide|lead|206}}||bgcolor="pink"|{{SimpleNuclide|lead|207}}||{{SimpleNuclide|lead|204}}
|-
|  8 ||[[oxygen]]       || [[isotopes of oxygen|3]]     || —
| {{SimpleNuclide|oxygen|16}}||{{SimpleNuclide|oxygen|18|link=yes}}||bgcolor="pink"|{{SimpleNuclide|oxygen|17}}
|-
| 10 ||[[neon]]         || [[isotopes of neon|3]]       || —
| {{SimpleNuclide|neon|20}}||{{SimpleNuclide|neon|22}}||bgcolor="pink"|{{SimpleNuclide|neon|21}}
|-
| 12 ||[[magnesium]]    || [[isotopes of magnesium|3]]  || —
| {{SimpleNuclide|magnesium|24}}||{{SimpleNuclide|magnesium|26}}||bgcolor="pink"|{{SimpleNuclide|magnesium|25}}
|-
| 14 ||[[silicon]]      || [[isotopes of silicon|3]]    || —
| {{SimpleNuclide|silicon|28}}||bgcolor="pink"|{{SimpleNuclide|silicon|29}}||{{SimpleNuclide|silicon|30}}
|-
| 18 ||[[argon]]        || [[isotopes of argon|3]]      || —
| {{SimpleNuclide|argon|40}}||{{SimpleNuclide|argon|36}}||{{SimpleNuclide|argon|38}}
|-
|  2 ||[[helium]]       || [[isotopes of helium|2]]     || — ||{{SimpleNuclide|helium|4|link=yes}}||bgcolor="pink"|{{SimpleNuclide|helium|3|link=yes}}
|-
|  6 ||[[carbon]]       || [[isotopes of carbon|2]]     || —
||{{SimpleNuclide|carbon|12|link=yes}}||bgcolor="pink"|{{SimpleNuclide|carbon|13|link=yes}}
|-
| 92 ||[[uranium]]      || [[isotopes of uranium|0]] || 2 || '''{{SimpleNuclide|uranium|238|link=yes}}'''{{efn|name=Note3}}||bgcolor="pink"|'''{{SimpleNuclide|uranium|235|link=yes}}'''
|-
|  4 ||[[beryllium]]    || [[isotopes of beryllium|1]]  || — ||bgcolor="pink"|{{SimpleNuclide|beryllium|9}}
|-
| 90 ||[[thorium]]      || [[isotopes of thorium|0]] || 1 || '''{{SimpleNuclide|thorium|232|link=yes}}'''{{efn|name=Note3}}
|}</div><div style="float: left; margin: 5px;">
{|class="sortable wikitable" align="top" style="text-align:center"
|+Primordial isotopes of odd-Z elements
|-
! Z<br>
! Element<br>
! <small>[[Stable nuclide|Stab]]<br></small>
! <small>''[[Primordial element|Dec]]''</small><br>
! class="unsortable" colspan="3"|<small>'''unstable: bold'''<div style="background:pink">odd [[neutron number|N]] in pink</div></small>
|-
| 19 ||[[potassium]]    || [[isotopes of potassium|2]]  || 1 ||{{SimpleNuclide|potassium|39}}||{{SimpleNuclide|potassium|41}}||bgcolor="pink"|'''{{SimpleNuclide|potassium|40|link=yes}}'''
|-
|  1 ||[[hydrogen]]     || [[isotopes of hydrogen|2]]   || — ||{{SimpleNuclide|hydrogen|1|link=yes}}||bgcolor="pink"|{{SimpleNuclide|hydrogen|2|link=yes}}
|-
|  3 ||[[lithium]]      || [[isotopes of lithium|2]]    || — || {{SimpleNuclide|lithium|7}}||bgcolor="pink"|{{SimpleNuclide|lithium|6}}
|-
|  5 ||[[boron]]        || [[isotopes of boron|2]]      || — ||{{SimpleNuclide|boron|11}}||bgcolor="pink"|{{SimpleNuclide|boron|10}}
|-
|  7 ||[[nitrogen]]     || [[isotopes of nitrogen|2]]   || — ||bgcolor="pink"|{{SimpleNuclide|nitrogen|14}}||{{SimpleNuclide|nitrogen|15}}
|-
| 17 ||[[chlorine]]     || [[isotopes of chlorine|2]]   || — ||{{SimpleNuclide|chlorine|35}}||{{SimpleNuclide|chlorine|37|link=yes}}
|-
| 29 ||[[copper]]       || [[isotopes of copper|2]]     || — ||{{SimpleNuclide|copper|63}}||{{SimpleNuclide|copper|65}}
|-
| 31 ||[[gallium]]      || [[isotopes of gallium|2]]    || — ||{{SimpleNuclide|gallium|69}}||{{SimpleNuclide|gallium|71}}
|-
| 35 ||[[bromine]]      || [[isotopes of bromine|2]]    || — ||{{SimpleNuclide|bromine|79}}||{{SimpleNuclide|bromine|81}}
|-
| 47 ||[[silver]]       || [[isotopes of silver|2]]     || — ||{{SimpleNuclide|silver|107}}||{{SimpleNuclide|silver|109}}
|-
| 51 ||[[antimony]]     || [[isotopes of antimony|2]]   || — ||{{SimpleNuclide|antimony|121}}||{{SimpleNuclide|antimony|123}}
|-
| 73 ||[[tantalum]]     || [[isotopes of tantalum|2]]   || — ||{{SimpleNuclide|tantalum|181}}||bgcolor="pink"|<small>{{SimpleNuclide|tantalum|180|m}}</small>
|-
| 77 ||[[iridium]]      || [[isotopes of iridium|2]]    || — ||{{SimpleNuclide|iridium|193}}||{{SimpleNuclide|iridium|191}}
|-
| 81 ||[[thallium]]     || [[isotopes of thallium|2]]   || — ||{{SimpleNuclide|thallium|205}}||{{SimpleNuclide|thallium|203}}
|-
| 23 ||[[vanadium]]     || [[isotopes of vanadium|1]]   || 1 ||{{SimpleNuclide|vanadium|51}}||bgcolor="pink"|'''{{SimpleNuclide|vanadium|50}}'''
|-
| 37 ||[[rubidium]]     || [[isotopes of rubidium|1]]   || 1 ||{{SimpleNuclide|rubidium|85}}||'''{{SimpleNuclide|rubidium|87}}'''
|-
| 49 ||[[indium]]       || [[isotopes of indium|1]]     || 1 ||'''{{SimpleNuclide|indium|115}}'''||{{SimpleNuclide|indium|113}}
|-
| 57 ||[[lanthanum]]    || [[isotopes of lanthanum|1]]  || 1 ||{{SimpleNuclide|lanthanum|139}}||bgcolor="pink"|'''{{SimpleNuclide|lanthanum|138}}'''
|-
| 63 ||[[europium]]     || [[isotopes of europium|1]]   || 1 ||{{SimpleNuclide|europium|153}}||'''{{SimpleNuclide|europium|151}}'''
|-
| 71 ||[[lutetium]]     || [[isotopes of lutetium|1]]   || 1 ||{{SimpleNuclide|lutetium|175}}||bgcolor="pink"|'''{{SimpleNuclide|lutetium|176}}'''
|-
| 75 ||[[rhenium]]      || [[isotopes of rhenium|1]]    || 1 ||'''{{SimpleNuclide|rhenium|187}}'''||{{SimpleNuclide|rhenium|185}}
|-
|  9 ||[[fluorine]]     || [[isotopes of fluorine|1]]   || — ||{{SimpleNuclide|fluorine|19}}
|-
| 11 ||[[sodium]]       || [[isotopes of sodium|1]]     || — ||{{SimpleNuclide|sodium|23}}
|-
| 13 ||[[aluminium]]    || [[isotopes of aluminium|1]]  || — ||{{SimpleNuclide|aluminium|27}}
|-
| 15 ||[[phosphorus]]   || [[isotopes of phosphorus|1]] || — ||{{SimpleNuclide|phosphorus|31}}
|-
| 21 ||[[scandium]]     || [[isotopes of scandium|1]]   || — ||{{SimpleNuclide|scandium|45}}
|-
| 25 ||[[manganese]]    || [[isotopes of manganese|1]]  || — ||{{SimpleNuclide|manganese|55}}
|-
| 27 ||[[cobalt]]       || [[isotopes of cobalt|1]]     || — ||{{SimpleNuclide|cobalt|59}}
|-
| 33 ||[[arsenic]]      || [[isotopes of arsenic|1]]    || — ||{{SimpleNuclide|arsenic|75}}
|-
| 39 ||[[yttrium]]      || [[isotopes of yttrium|1]]    || — ||{{SimpleNuclide|yttrium|89}}
|-
| 41 ||[[niobium]]      || [[isotopes of niobium|1]]    || — ||{{SimpleNuclide|niobium|93}}
|-
| 45 ||[[rhodium]]      || [[isotopes of rhodium|1]]    || — ||{{SimpleNuclide|rhodium|103}}
|-
| 53 ||[[iodine]]       || [[isotopes of iodine|1]]     || — ||{{SimpleNuclide|iodine|127}}
|-
| 55 ||[[caesium]]      || [[isotopes of caesium|1]]    || — ||{{SimpleNuclide|caesium|133}}
|-
| 59 ||[[praseodymium]] || [[isotopes of praseodymium|1]] || — ||{{SimpleNuclide|praseodymium|141}}
|-
| 65 ||[[terbium]]      || [[isotopes of terbium|1]]    || — ||{{SimpleNuclide|terbium|159}}
|-
| 67 ||[[holmium]]      || [[isotopes of holmium|1]]    || — ||{{SimpleNuclide|holmium|165}}
|-
| 69 ||[[thulium]]      || [[isotopes of thulium|1]]    || — ||{{SimpleNuclide|thulium|169}}
|-
| 79 ||[[gold]]         || [[isotopes of gold|1]]       || — ||{{SimpleNuclide|gold|197}}
|-
| 83 ||[[bismuth]]         || [[isotopes of bismuth|0]]       || 1 ||'''{{SimpleNuclide|bismuth|209|link=yes}}'''
|}</div>
{{Clear}}

==Elements with no primordial isotopes==
<div style="float: left; margin: 5px;">
{|class="wikitable sortable" align="top" style="text-align:center"
|+No primordial isotopes<br/>Longest-lived isotope > 1 day
|-
! [[Atomic number|Z]]<br/>
! Element<br/>
! class="unsortable"| [[Half-life|t<sup>1⁄2</sup>]]{{efn|name=Note6}}<ref name=nuclidetable/>
! class="unsortable"| Longest-<br/>lived<br/>isotope
|-
| 94 || [[plutonium]]    || {{val|8.13|e=7|ul=yr}} || {{SimpleNuclide|plutonium|244}}
|-
| 96 || [[curium]]       || {{val|1.56|e=7|u=yr}}  || {{SimpleNuclide|curium|247}}
|-
| 43 || [[technetium]]   || {{val|4.21|e=6|u=yr}}   || {{SimpleNuclide|technetium|97}}{{efn|name=Note1}}
|-
| 93 || [[neptunium]]    || {{val|2.14|e=6|u=yr}} || {{SimpleNuclide|neptunium|237}}
|-
| 91 || [[protactinium]] || 32,700 yr || {{SimpleNuclide|protactinium|231}}
|-
| 95 || [[americium]]    || 7,370 yr  || {{SimpleNuclide|americium|243}}
|-
| 88 || [[radium]]       || 1,600 yr  || {{SimpleNuclide|radium|226}}
|-
| 97 || [[berkelium]]    || 1,380 yr  || {{SimpleNuclide|berkelium|247}}
|-
| 98 || [[californium]]  || 900 yr    || {{SimpleNuclide|californium|251}}
|-
| 84 || [[polonium]]     || 124 yr    || {{SimpleNuclide|polonium|209}}
|-
| 89 || [[actinium]]     || 21.772 yr  || {{SimpleNuclide|actinium|227}}
|-
| 61 || [[promethium]]   || 17.7 yr   || {{SimpleNuclide|promethium|145}}{{efn|name=Note1}}
|-
| 99 || [[einsteinium]]  || 1.293 yr   || {{SimpleNuclide|einsteinium|252}}{{efn|name=Note5}}
|-
|100 || [[fermium]]      || 100.5 [[day|d]]  || {{SimpleNuclide|fermium|257}}{{efn|name=Note5}}
|-
|101 || [[mendelevium]]  || 51.6 d   || {{SimpleNuclide|mendelevium|258}}{{efn|name=Note5}}
|-
| 86 || [[radon]]        || 3.823 d   || {{SimpleNuclide|radon|222}}
|}</div><div style="float: left; margin: 5px;">
{|class="wikitable sortable" align="top" style="text-align:center"
|+No primordial isotopes<br/>Longest-lived isotope < 1 day
|-
! [[Atomic number|Z]]<br/>
! Element<br/>
! class="unsortable"| [[Half-life|t<sup>1⁄2</sup>]]{{efn|name=Note6}}<ref name=nuclidetable/>
! class="unsortable"| Longest-<br/>lived<br/>isotope
|-
|105 || [[dubnium]]      || 16 [[hour|h]]   || {{SimpleNuclide|dubnium|268}}{{efn|name=Note5}}
|-
|103 || [[lawrencium]]   || 11 h || {{SimpleNuclide|lawrencium|266}}{{efn|name=Note5}}
|-
| 85 || [[astatine]]     || 8.1 h    || {{SimpleNuclide|astatine|210}}
|-
|102 || [[nobelium]]     || 58 [[minute|min]]     || {{SimpleNuclide|nobelium|259}}{{efn|name=Note5}}
|-
|104 || [[rutherfordium]]|| 48 min    || {{SimpleNuclide|rutherfordium|267}}{{efn|name=Note5}}
|-
| 87 || [[francium]]     || 22 min  || {{SimpleNuclide|francium|223}}
|-
|106 || [[seaborgium]]   || 14 min     || {{SimpleNuclide|seaborgium|269}}{{efn|name=Note5}}
|-
|107 || [[bohrium]]      || 2.4 min || {{SimpleNuclide|bohrium|270}}{{efn|name=Note5}}
|-
|111 || [[roentgenium]]  || 1.7 min     || {{SimpleNuclide|roentgenium|282}}{{efn|name=Note5}}
|-
|112 || [[copernicium]]  || 28 [[second|s]]      || {{SimpleNuclide|copernicium|285}}{{efn|name=Note5}}
|-
|108 || [[hassium]]      || 16 s       || {{SimpleNuclide|hassium|269}}{{efn|name=Note5}}
|-
|110 || [[darmstadtium]] || 12.7 s      || {{SimpleNuclide|darmstadtium|281}}{{efn|name=Note5}}
|-
|113 || [[nihonium]]     || 9.5 s       || {{SimpleNuclide|nihonium|286}}{{efn|name=Note5}}
|-
|109 || [[meitnerium]]   || 4.5 s       || {{SimpleNuclide|meitnerium|278}}{{efn|name=Note5}}
|-
|114 || [[flerovium]]    || 1.9 s       || {{SimpleNuclide|flerovium|289}}{{efn|name=Note5}}
|-
|115 || [[moscovium]]    || 650 [[millisecond|ms]]   || {{SimpleNuclide|moscovium|290}}{{efn|name=Note5}}
|-
|116 || [[livermorium]]  || 57 ms || {{SimpleNuclide|livermorium|293}}{{efn|name=Note5}}
|-
|117 || [[tennessine]]   || 51 ms || {{SimpleNuclide|tennessine|294}}{{efn|name=Note5}}
|-
|118 || [[oganesson]]    || 690 [[microsecond|μs]]   || {{SimpleNuclide|oganesson|294}}{{efn|name=Note5}}
|}</div>
<!--[[File:Periodic Table by Number of Stable Isotopes.PNG|right|450px|thumb|Periodic table colored according to the number of stable isotopes. Elements with odd atomic numbers have at most one or two stable isotopes, while elements up to lead with even atomic numbers all have three or more stable isotopes, except for the first three: helium, beryllium, and carbon.]]-->

{{Periodic table (transuranium element)}}

{{Clear}}

==See also==
*[[Island of stability]]
*{{section link|Isotope#Nuclear properties and stability}}
*[[List of nuclides]]
*[[List of radioactive nuclides by half-life]]
*[[Primordial nuclide]]
*[[Stable nuclide]]
*[[Stable isotope ratio]]
*[[Table of nuclides]]

==Footnotes==
{{notelist|refs=
{{efn|name=Note1|1=See [[Isotopes of technetium#Stability of technetium isotopes|Stability of technetium isotopes]] and [[Isotopes of promethium#Stability of promethium isotopes|Stability of promethium isotopes]] for a discussion as to why technetium and promethium have no stable isotopes.}}
{{efn|name=Note2|1=There are unstable isotopes with extremely long half-lives that are also found on Earth, and some of them are even more abundant than all the stable isotopes of a given element (for example, beta-active <sup>187</sup>Re is twice as abundant as stable <sup>185</sup>Re). Also, a bigger natural abundance of an isotope just implies that its formation was favored by the [[stellar nucleosynthesis]] process that produced the matter now constituting the [[Earth]] (and, of course, the rest of the [[Solar System]]) (see also [[Formation and evolution of the Solar System]]). In the case of [[argon]] the cosmically rarer {{chem|40|Ar}} dominates on Earth over {{chem|36|Ar}} as argon is too volatile to have been retained in the early proto-atmosphere of Earth while {{chem|40|Ar}} is a decay product of long-lived and non-volatile {{chem|40|K|link=potassium-40}}. Most argon in Earth's atmosphere is a product of potassium-40 decay. Most argon in the universe is not. At the present time 0.012% (120 [[parts per million|ppm]]) of potassium on Earth is {{chem|40|K}}. Taking the [[age of Earth]] and the half life of {{chem|40|K}} (~1.25 billion years), this ratio was approximately an order of magnitude higher when the planet first formed. About 10.72% of that since-decayed {{chem|40|K}} produced {{chem|40|Ar}}, the rest having decayed to {{chem|40|Ca}}.}}
{{efn|name=Note3|1=Of these three primordial but unstable elements, two more non-primordial isotopes are found in nature in significant amounts: {{SimpleNuclide|uranium|234|link=yes}} and {{SimpleNuclide|thorium|230|link=yes}}, both radiogenic as decay products of {{SimpleNuclide|uranium|238|link=yes}}.}}
{{efn|name=Note4|1=See many different industrial and medical applications of radioactive elements in [[Radionuclide]], [[Nuclear medicine]], [[Common beta emitters]], [[Commonly used gamma-emitting isotopes]], [[Fluorine-18]], [[Cobalt-60]], [[Strontium-90]], [[Technetium-99m]], [[Iodine-123]], [[Iodine-124]], [[Promethium-147]], [[Iridium-192]], etc.}}
{{efn|name=Note5|1=For elements with a higher atomic number than californium (with Z>98), there might exist [[island of stability|undiscovered isotopes that are more stable than the known ones]].}}
{{efn|name=Note6|1=''Legend:'' yr=[[annum|year]], d=[[day]], h=[[hour]], min=[[minute]], s=[[second]].}}
}}

{{Clear}}

==References==
{{Reflist}}

{{Navbox periodic table}}

[[Category:Lists of chemical elements|* Stability of isotopes]]