Silicon-29

Main isotopes of silicon

iso NA half-life DM DE (MeV) DP 28Si 92.2% is stable with 14 neutrons 29Si 4.7% is stable with 15 neutrons 30Si 3.1% is stable with 16 neutrons 31Si trace 2.62 h β− 1.495 31P 32Si trace 153 y β− 13.020 32P
Standard atomic weight (Ar)	[28.084, 28.086] Conventional: 28.085

Silicon (₁₄Si) has 24 known isotopes, with mass numbers ranging from 22 to 45. 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 relative atomic mass is 28.0855(3). The least stable is usually ⁴³Si with a half-life greater than 60 nanoseconds.

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