Editing Silicon (section)

===Isotopes===
{{Main|Isotopes of silicon}}
Naturally occurring silicon is composed of three stable [[isotope]]s, <sup>28</sup>Si (92.23%), <sup>29</sup>Si (4.67%), and <sup>30</sup>Si (3.10%).{{NUBASE2020|ref}} Out of these, only <sup>29</sup>Si is of use in [[NMR]] and [[EPR spectroscopy]],<ref>{{cite web| url =http://www.nyu.edu/cgi-bin/cgiwrap/aj39/NMRmap.cgi|access-date =2011-10-20| title =Interactive NMR Frequency Map| author =Jerschow, Alexej|publisher =New York University}}</ref> as it is the only one with a nuclear spin (''I'' ={{sfrac|1|2}}).{{sfn|Greenwood|Earnshaw|1997|p=330}} All three are produced in [[Type Ia supernovae]]<ref>{{cite book |last1=Seitenzahl |first1=Ivo Rolf |last2=Townsley |first2=Dean M. |title=Handbook of Supernovae |chapter=Nucleosynthesis in Thermonuclear Supernovae |date=2017 |pages=1955–1978 |doi=10.1007/978-3-319-21846-5_87|arxiv=1704.00415 |bibcode=2017hsn..book.1955S |isbn=978-3-319-21845-8 |s2cid=118993185 }}</ref><ref>{{cite journal |last1=Khokhlov |first1=A. M. |last2=Oran |first2=E. S. |last3=Wheeler |first3=J. C. |title=Deflagration-to-Detonation Transition in Thermonuclear Supernovae |journal=The Astrophysical Journal |date=April 1997 |volume=478 |issue=2 |pages=678–688 |doi=10.1086/303815|arxiv=astro-ph/9612226 |bibcode=1997ApJ...478..678K |s2cid=53486905 }}</ref> through the [[oxygen-burning process]], with <sup>28</sup>Si being made as part of the [[alpha process]] and hence the most abundant. The fusion of <sup>28</sup>Si with alpha particles by [[photodisintegration]] rearrangement in stars is known as the [[silicon-burning process]]; it is the last stage of [[stellar nucleosynthesis]] before the rapid collapse and violent explosion of the star in question in a [[type II supernova]].<ref name="Cameron">{{cite journal|last1=Cameron |first1=A.G.W. |year=1973 |title=Abundance of the Elements in the Solar System |url=http://pubs.giss.nasa.gov/docs/1973/1973_Cameron_1.pdf |journal=Space Science Reviews |volume=15 |issue=1 |pages=121–146 |doi=10.1007/BF00172440 |bibcode=1973SSRv...15..121C |s2cid=120201972 |url-status=dead |archive-url=https://web.archive.org/web/20111021030549/http://pubs.giss.nasa.gov/docs/1973/1973_Cameron_1.pdf |archive-date=2011-10-21 }}</ref>

Twenty-two [[radioisotopes]] have been characterized, the two stablest being <sup>32</sup>Si with a [[half-life]] of about 150&nbsp;years, and <sup>31</sup>Si with a half-life of 2.62&nbsp;hours.{{NUBASE2020|ref}} All the remaining [[Radioactive decay|radioactive]] isotopes have half-lives that are less than seven seconds, and the majority of these have half-lives that are less than one-tenth of a second.{{NUBASE2020|ref}} Silicon has one known [[nuclear isomer]], <sup>34m</sup>Si, with a half-life less than 210&nbsp;nanoseconds.{{NUBASE2020|ref}} <sup>32</sup>Si undergoes low-energy [[beta decay]] to [[phosphorus-32|<sup>32</sup>P]] and then stable <sup>32</sup>[[sulfur|S]]. <sup>31</sup>Si may be produced by the [[neutron activation]] of natural silicon and is thus useful for quantitative analysis; it can be easily detected by its characteristic beta decay to stable <sup>31</sup>[[phosphorus|P]], in which the emitted electron carries up to 1.48&nbsp;[[electronvolt|MeV]] of energy.{{sfn|Greenwood|Earnshaw|1997|p=330}}

The known isotopes of silicon range in [[mass number]] from 22 to 46.{{NUBASE2020|ref}}<ref name="45Si,46Si">{{cite journal | last1=Yoshimoto | first1=Masahiro | last2=Suzuki | first2=Hiroshi | last3=Fukuda | first3=Naoki | last4=Takeda | first4=Hiroyuki | last5=Shimizu | first5=Yohei | last6=Yanagisawa | first6=Yoshiyuki | last7=Sato | first7=Hiromi | last8=Kusaka | first8=Kensuke | last9=Ohtake | first9=Masao | last10=Yoshida | first10=Koichi | last11=Michimasa | first11=Shin’ichiro | title=Discovery of Neutron-Rich Silicon Isotopes <sup>45,46</sup>Si | journal=Progress of Theoretical and Experimental Physics | publisher=Oxford University Press (OUP) | volume=2024 | issue=10 | year=2024 | issn=2050-3911 | doi=10.1093/ptep/ptae155 | doi-access=free}}</ref> The most common [[decay mode]] of the isotopes with mass numbers lower than the three stable isotopes is [[positron emission|β<sup>+</sup> decay]], primarily forming aluminium isotopes (13 protons) as [[decay product]]s.{{NUBASE2020|ref}} The most common decay mode for the heavier unstable isotopes is beta decay, primarily forming phosphorus isotopes (15 protons) as decay products.{{NUBASE2020|ref}}

Silicon can enter the oceans through groundwater and [[riverine]] transport. Large fluxes of groundwater input have an isotopic composition which is distinct from riverine silicon inputs. Isotopic variations in groundwater and riverine transports contribute to variations in oceanic <sup>30</sup>Si values. Currently, there are substantial differences in the isotopic values of deep water in the world's [[Oceanic basin|ocean basins]]. Between the Atlantic and Pacific oceans, there is a deep water <sup>30</sup>Si gradient of greater than 0.3 parts per thousand. <sup>30</sup>Si is most commonly associated with productivity in the oceans.<ref>{{cite journal |last1=Reynolds |first1=B. C. |title=Modeling the modern marine δ 30 Si distribution: MODELING THE MODERN MARINE δ 30 Si DISTRIBUTION |journal=Global Biogeochemical Cycles |date=June 2009 |volume=23 |issue=2 |pages=1–13 |doi=10.1029/2008GB003266|s2cid=128652214 |doi-access=free }}</ref>