Isotopes of silicon

Isotope data
silicon symbol icon

Silicon isotopes are used in a variety of applications. Si-28 has been suggested to improve the thermal conductivity of semiconductors. Si-29 is used extensively in NMR spectroscopy. Si-30 has been used to produce the radioisotope Si-31. Si-30 has also been used to study the self-diffusivity of Silicon and it has been used to study the isotope effect on superconductivity. Silicon isotopes can be obtained from Trace Sciences International.

Naturally occurring isotopes

This table shows information about naturally occuring isotopes, their atomic masses, their natural abundances, their nuclear spins, and their magnetic moments. Further data for radioisotopes (radioactive isotopes) of silicon are listed (including any which occur naturally) below.
Isotope Atomic mass (ma/u) Natural abundance (atom %) Nuclear spin (I) Magnetic moment (μ/μN)
28Si 27.9769271 (7) 92.2297 (7) 0 0
29Si 28.9764949 (7) 4.6832 (5) 1/2 -0.55529
30Si 29.9737707 (7) 3.0872 (5) 0 0

Isotopic abundances of Si
In the above picture, the most intense ion is set to 100% since this corresponds best to the output from a mass spectrometer. This is not to be confused with the relative percentage isotope abundances which total 100% for all the naturally occurring isotopes.

Radiosotope data

Further data for naturally occuring isotopes of silicon are listed above. This table gives information about some radiosotopes of silicon, their masses, their half-lives, their modes of decay, their nuclear spins, and their nuclear magnetic moments.
Isotope Mass Half-life Mode of decay Nuclear spin Nuclear magnetic moment
26Si 25.992330 2.23 s EC to 26Al 0
27Si 26.9867041 4.14 s EC to 27Al 5/2
31Si 30.975362 2.62 h β- to 31P 3/2
32Si 31.974148 160 y β- to 32P 0
33Si 32.97800 6.1 s β- to 33P 3/2
34Si 33.97858 2.8 s β- to 34P 0

Sheffield ChemPuter isotope pattern calculator

You can use WebElements to calculate an isotope pattern for an arbitrary chemical formula:

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Note the following when entering your formula:

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  • 'Pseudoelements' such as Me, Ph, Cp, and many others are OK
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  • Experiment with your formula to see what is possible

References

  1. Naturally occurring isotope abundances: Commission on Atomic Weights and Isotopic Abundances report for the International Union of Pure and Applied Chemistry in Isotopic Compositions of the Elements 1989, Pure and Applied Chemistry, 1998, 70, 217. [Copyright 1998 IUPAC]
  2. Masses, nuclear spins, and magnetic moments: I. Mills, T. Cvitas, K. Homann, N. Kallay, and K. Kuchitsu in Quantities, Units and Symbols in Physical Chemistry, Blackwell Scientific Publications, Oxford, UK, 1988. [Copyright 1988 IUPAC]
  3. For further information about radioisotopes see Jonghwa Chang's (Korea Atomic Energy Research Institute) Table of the Nuclides

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