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Silicon (14Si) has 14 known isotopes, with mass numbers ranging from 22 to 36. 28Si (the most abundant isotope, at 92.23%), 29Si (4.67%), and 30Si (3.1%) are stable. The longest-lived radioisotope is 32Si, which is produced by cosmic ray spallation of argon. Its half-life has been determined to be approximately 150 years (0.21 MeV), and it decays by beta emission to 32P (which has a 14.28 day half-life [1]) and then to 32S. After 32Si, 31Si has the second longest half-life at 157.3 minutes. All others have half-lives under 7 seconds. The least stable is usually 43Si with a half-life greater than 60 nanoseconds.
2. "Silicon." Chemicool Periodic Table. Chemicool.com. 09 Oct. 2012. Web. 11/11/2017
<https://www.chemicool.com/elements/silicon.html>.