Editing Beta decay (section)

==Nuclear transmutation==
[[File:Table isotopes en.svg|250px|right|thumb|Graph of isotopes by type of nuclear decay. Orange and blue nuclides are unstable, with the black squares between these regions representing stable nuclides. The unbroken line passing below many of the nuclides represents the theoretical position on the graph of nuclides for which proton number is the same as neutron number. The graph shows that elements with more than 20 protons must have more neutrons than protons, in order to be stable.]]
{{See also|Nuclear drip line}}
If the proton and neutron are part of an [[atomic nucleus]], the above described decay processes [[Nuclear transmutation|transmute]] one chemical element into another. For example:

<!-- Autogenerated using Phykiformulae 0.11 by SkyLined]]
Cs-137 _ _ -> Ba-137 + e- + !ve (beta_minus_decay)
Na-22 _ _ -> Ne-22 + e+ + ve (beta_plus_decay)
Na-22 + e- -> Ne-22 + ve _ _ (electron_capture)
-->:{|border="0"
|- style="height:2em;"
|{{nuclide|link=yes|caesium|137}}&nbsp;||&nbsp;||&nbsp;||→&nbsp;||{{nuclide|link=yes|barium|137}}&nbsp;||+&nbsp;||{{SubatomicParticle|link=yes|Electron}}&nbsp;||+&nbsp;||{{math|{{SubatomicParticle|link=yes|Electron Antineutrino}}}}&nbsp;||(beta minus decay)
|- style="height:2em;"
|{{nuclide|link=yes|sodium|22}}&nbsp;||&nbsp;||&nbsp;||→&nbsp;||{{nuclide|link=yes|neon|22}}&nbsp;||+&nbsp;||{{math|{{SubatomicParticle|link=yes|Positron}}}}&nbsp;||+&nbsp;||{{math|{{SubatomicParticle|link=yes|Electron Neutrino}}}}&nbsp;||(beta plus decay)
|- style="height:2em;"
|{{nuclide|link=yes|sodium|22}}&nbsp;||+&nbsp;||{{SubatomicParticle|link=yes|Electron}}&nbsp;||→&nbsp;||{{nuclide|link=yes|neon|22}}&nbsp;||+&nbsp;||{{math|{{SubatomicParticle|link=yes|Electron Neutrino}}}}&nbsp;||&nbsp;||&nbsp;||(electron capture)
|}

Beta decay does not change the number&nbsp;({{mvar|A}}) of [[nucleon]]s in the nucleus, but changes only its [[electric charge|charge]]&nbsp;{{mvar|Z}}. Thus the set of all [[nuclide]]s with the same&nbsp;{{mvar|A}} can be introduced; these [[isobar (nuclide)|''isobaric'' nuclides]] may turn into each other via beta decay. For a given {{mvar|A}} there is one that is most stable. It is said to be beta stable, because it presents a local minimum of the [[mass excess]]: if such a nucleus has {{math|(''A'', ''Z'')}} numbers, the neighbour nuclei {{math|(''A'', ''Z''−1)}} and {{math|(''A'', ''Z''+1)}} have higher mass excess and can beta decay into {{math|(''A'', ''Z'')}}, but not vice versa. For all odd mass numbers {{mvar|A}}, there is only one known beta-stable isobar. For even&nbsp;{{mvar|A}}, there are up to three different beta-stable isobars experimentally known; for example, {{nuclide|tin|124}}, {{nuclide|tellurium|124}}, and {{nuclide|xenon|124}} are all beta-stable. There are about 350 known [[beta-decay stable isobars|beta-decay stable nuclides]].<ref name="nndc_Inte">{{Cite web | title=Interactive Chart of Nuclides | url=http://www.nndc.bnl.gov/chart/ | publisher=National Nuclear Data Center, Brookhaven National Laboratory | access-date=2014-09-18 | archive-date=2018-10-10 | archive-url=https://web.archive.org/web/20181010070007/http://www.nndc.bnl.gov/chart/  }}</ref>

===Competition of beta decay types===
Usually unstable nuclides are clearly either "neutron rich" or "proton rich", with the former undergoing beta decay and the latter undergoing electron capture (or more rarely, due to the higher energy requirements, positron decay). However, in a few cases of odd-proton, odd-neutron radionuclides, it may be energetically favorable for the radionuclide to decay to an even-proton, even-neutron isobar either by undergoing beta-positive or beta-negative decay. 

Three types of beta decay in competition are illustrated by the single isotope {{nuclide|copper|64|link=yes}} (29 protons, 35 neutrons), which has a half-life of about 12.7 hours.<ref name="Cu-64">[http://www.lnhb.fr/nuclides/Cu-64_tables.pdf Atomic and Nuclear Data: Chapter 12 Cu-64 ] {{Webarchive|url=https://web.archive.org/web/20240502181344/http://www.lnhb.fr/nuclides/Cu-64_tables.pdf |date=2024-05-02 }} Laboratoire National Henri Becquerel, 2011. Retrieved on 2024-05-01.</ref> This isotope has one unpaired proton and one unpaired neutron, so either the proton or the neutron can decay.<ref name="Copper-64">{{cite web |last1=Gilbert |first1=Thomas R. |title=Problem 20: Copper-64 is an unusual radionuclide |url=https://www.vaia.com/en-us/textbooks/chemistry/chemistry-the-science-in-context-5-edition/chapter-19/problem-20-copper-64-is-an-unusual-radionuclide-in-that-it-m/ |website=Chemistry The Science in Context |publisher=Vaia |access-date=2 May 2024 |archive-date=2 May 2024 |archive-url=https://web.archive.org/web/20240502182148/https://www.vaia.com/en-us/textbooks/chemistry/chemistry-the-science-in-context-5-edition/chapter-19/problem-20-copper-64-is-an-unusual-radionuclide-in-that-it-m/ |url-status=live }}</ref> This particular nuclide is almost equally likely to undergo proton decay (by [[positron emission]], 18% or by [[electron capture]], 43%; both forming [[Isotopes of nickel|{{SimpleNuclide|Nickel|64}}]]) or neutron decay (by electron emission, 39%; forming [[Isotopes of zinc|{{SimpleNuclide|Zinc|64}}]]).<ref name="Cu-64"/><ref name="Copper-64"/>

===Stability of naturally occurring nuclides===
Most naturally occurring nuclides on earth are beta stable. Nuclides that are not beta stable have [[half-life|half-lives]] ranging from under a second to periods of time significantly greater than the [[age of the universe]]. One common example of a long-lived isotope is the odd-proton odd-neutron nuclide {{nuclide|link=yes|Potassium|40}}, which undergoes all three types of beta decay ({{SubatomicParticle|Beta-}}, {{SubatomicParticle|Beta+}} and electron capture) with a half-life of {{val|1.277|e=9|u=years}}.<ref>
{{Cite web
 |title=WWW Table of Radioactive Isotopes, Potassium 40
 |publisher=Lawrence Berkeley National Laboratory
 |work=LBNL Isotopes Project
 |access-date=2014-09-18
 |url=http://ie.lbl.gov/toi/nuclide.asp?iZA=190040
 
 |archive-url=https://web.archive.org/web/20131009123338/http://ie.lbl.gov/toi/nuclide.asp?iZA=190040
 |archive-date=2013-10-09
}}</ref>