Isotopes of silicon

Main isotopes of silicon

Isotope			Decay
	abundance	half-life (t_1/2)	mode	product
²⁸Si	92.2%	stable
²⁹Si	4.7%	stable
³⁰Si	3.1%	stable
³¹Si	trace	2.62 h	β⁻	³¹P
³²Si	trace	153 y	β⁻	³²P

Standard atomic weight (A_r)

[28.084, 28.086]^[1]
Conventional: 28.085

Silicon (₁₄Si) has 25 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 ) 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.

A chart showing the relative abundances of the naturally occurring isotopes of Silicon.

List of isotopes

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)^[2]	daughter isotope(s)^{[n 1]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
²²Si	14	8	22.03453(22)#	29(2) ms	β⁺ (68%)	²²Al	0+
²²Si	14	8	22.03453(22)#	29(2) ms	β⁺, p (32%)	²¹Mg	0+
²³Si	14	9	23.02552(21)#	42.3(4) ms	β⁺	²³Al	3/2+#
²⁴Si	14	10	24.011546(21)	140(8) ms	β⁺ (92%)	²⁴Al	0+
²⁴Si	14	10	24.011546(21)	140(8) ms	β⁺, p (8%)	²³Mg	0+
²⁵Si	14	11	25.004106(11)	220(3) ms	β⁺ (63.19%)	²⁵Al	5/2+
²⁵Si	14	11	25.004106(11)	220(3) ms	β⁺, p (36.8%)	²⁴Mg	5/2+
²⁶Si	14	12	25.992330(3)	2.234(13) s	β⁺	²⁶Al	0+
²⁷Si	14	13	26.98670491(16)	4.16(2) s	β⁺	²⁷Al	5/2+
²⁸Si	14	14	27.9769265325(19)	Stable			0+	0.92223(19)	0.92205–0.92241
²⁹Si	14	15	28.976494700(22)	Stable			1/2+	0.04685(8)	0.04678–0.04692
³⁰Si	14	16	29.97377017(3)	Stable			0+	0.03092(11)	0.03082–0.03102
³¹Si	14	17	30.97536323(4)	157.3(3) min	β⁻	³¹P	3/2+
³²Si	14	18	31.97414808(5)	153(19) y	β⁻	³²P	0+	trace	cosmogenic
³³Si	14	19	32.978000(17)	6.18(18) s	β⁻	³³P	(3/2+)
³⁴Si	14	20	33.978576(15)	2.77(20) s	β⁻	³⁴P	0+
³⁵Si	14	21	34.98458(4)	780(120) ms	β⁻ (94.74%)	³⁵P	7/2−#
³⁵Si	14	21	34.98458(4)	780(120) ms	β⁻, n (5.26%)	³⁴P	7/2−#
³⁶Si	14	22	35.98660(13)	0.45(6) s	β⁻ (88%)	³⁶P	0+
³⁶Si	14	22	35.98660(13)	0.45(6) s	β⁻, n (12%)	³⁵P	0+
³⁷Si	14	23	36.99294(18)	90(60) ms	β⁻ (83%)	³⁷P	(7/2−)#
³⁷Si	14	23	36.99294(18)	90(60) ms	β⁻, n (17%)	³⁶P	(7/2−)#
³⁸Si	14	24	37.99563(15)	90# ms [>1 µs]	β⁻, n	³⁷P	0+
³⁸Si	14	24	37.99563(15)	90# ms [>1 µs]	β⁻	³⁸P	0+
³⁹Si	14	25	39.00207(36)	47.5(20) ms	β⁻	³⁹P	7/2−#
⁴⁰Si	14	26	40.00587(60)	33.0(10) ms	β⁻	⁴⁰P	0+
⁴¹Si	14	27	41.01456(198)	20.0(25) ms	β⁻	⁴¹P	7/2−#
⁴²Si	14	28	42.01979(54)#	13(4) ms	β⁻	⁴²P	0+
⁴³Si	14	29	43.02866(75)#	15# ms [>260 ns]			3/2−#
⁴⁴Si	14	30	44.03526(86)#	10# ms			0+

↑ Bold for stable isotopes

Notes

The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.
Blank spaces in the "natural abundance" and "range of natural variation" column show that the isotope discussed in the corresponding row is synthetic.

References

Isotope masses from:
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23.
Isotopic compositions and standard atomic masses from:
- J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
- M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23.
- National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005. Check date values in: |access-date= (help)
- N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.

↑ Meija, J.; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure Appl. Chem. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
↑ "Universal Nuclide Chart". nucleonica. (Registration required (help)).

External links

Silicon isotopes data from The Berkeley Laboratory Isotopes Project's

Isotopes of aluminium	Isotopes of silicon	Isotopes of phosphorus
Table of nuclides

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