Isotopes of silicon

Silicon (Si) 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.