Isotopes of tin

Tin (Sn) is the element with the greatest number of stable isotopes (ten; three of them are potentially radioactive but have not been observed to decay), which is probably related to the fact that 50 is a "magic number" of protons. 29 additional unstable isotopes are known, including the "doubly magic" tin-100 (¹⁰⁰Sn) (discovered in 1994)^[1] and tin-132 (¹³²Sn). The longest-lived radioisotope is ¹²⁶Sn, with a half-life of 230,000 years. The other 28 radioisotopes have half-lives less than a year.

Relative atomic mass: 118.74.

Tin-121m

Tin-121m is a radioisotope and nuclear isomer of tin with a half-life of 43.9 years.

In a normal thermal reactor, it has a very low fission product yield; thus, this isotope is not a significant contributor to nuclear waste. Fast fission or fission of some heavier actinides will produce ^121mSn at higher yields. For example, its yield from U-235 is 0.0007% per thermal fission and 0.002% per fast fission.^[2]

Tin-126

Yield, % per fission^[2]

	Thermal	Fast	14 MeV
^232Th	not fissile	0.0481 ± 0.0077	0.87 ± 0.20
^233U	0.224 ± 0.018	0.278 ± 0.022	1.92 ± 0.31
^235U	0.056 ± 0.004	0.0137 ± 0.001	1.70 ± 0.14
^238U	not fissile	0.054 ± 0.004	1.31 ± 0.21
^239Pu	0.199 ± 0.016	0.26 ± 0.02	2.02 ± 0.22
^241Pu	0.082 ± 0.019	0.22 ± 0.03	?

Tin-126 is a radioisotope of tin and one of only 7 long-lived fission products. While tin-126's halflife of 230,000 years translates to a low specific activity that limits its radioactive hazard, its short-lived decay product, antimony-126, emits high-energy gamma radiation, making external exposure to tin-126 a potential concern.

¹²⁶Sn is in the middle of the mass range for fission products. Thermal reactors, which make up almost all current nuclear power plants, produce it at a very low yield (0.056% for ²³⁵U), since slow neutrons almost always fission ²³⁵U or ²³⁹Pu into unequal halves. Fast fission in a fast reactor or nuclear weapon, or fission of some heavy minor actinides like californium, will produce it at higher yields.

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Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)[3][n 1]	daughter isotope(s)[n 2]	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
^99Sn[n 3]	50	49	98.94933(64)#	5# ms			9/2+#
^100Sn[n 4]	50	50	99.93904(76)	1.1(4) s [0.94(+54−27) s]	β^+ (83%)	^100In	0+
					β^+, p (17%)	^99Cd
^101Sn	50	51	100.93606(32)#	3(1) s	β^+	^101In	5/2+#
					β^+, p (rare)	^100Cd
^102Sn	50	52	101.93030(14)	4.5(7) s	β^+	^102In	0+
					β^+, p (rare)	^101Cd
^102mSn	2017(2) keV			720(220) ns			(6+)
^103Sn	50	53	102.92810(32)#	7.0(6) s	β^+	^103In	5/2+#
					β^+, p (rare)	^102Cd
^104Sn	50	54	103.92314(11)	20.8(5) s	β^+	^104In	0+
^105Sn	50	55	104.92135(9)	34(1) s	β^+	^105In	(5/2+)
					β^+, p (rare)	^104Cd
^106Sn	50	56	105.91688(5)	115(5) s	β^+	^106In	0+
^107Sn	50	57	106.91564(9)	2.90(5) min	β^+	^107In	(5/2+)
^108Sn	50	58	107.911925(21)	10.30(8) min	β^+	^108In	0+
^109Sn	50	59	108.911283(11)	18.0(2) min	β^+	^109In	5/2(+)
^110Sn	50	60	109.907843(15)	4.11(10) h	EC	^110In	0+
^111Sn	50	61	110.907734(7)	35.3(6) min	β^+	^111In	7/2+
^111mSn	254.72(8) keV			12.5(10) µs			1/2+
^112Sn	50	62	111.904818(5)	Observationally Stable[n 5]			0+	0.0097(1)
^113Sn	50	63	112.905171(4)	115.09(3) d	β^+	^113In	1/2+
^113mSn	77.386(19) keV			21.4(4) min	IT (91.1%)	^113Sn	7/2+
					β^+ (8.9%)	^113In
^114Sn	50	64	113.902779(3)	Stable[n 6]			0+	0.0066(1)
^114mSn	3087.37(7) keV			733(14) ns			7−
^115Sn	50	65	114.903342(3)	Stable[n 6]			1/2+	0.0034(1)
^115m1Sn	612.81(4) keV			3.26(8) µs			7/2+
^115m2Sn	713.64(12) keV			159(1) µs			11/2−
^116Sn	50	66	115.901741(3)	Stable[n 6]			0+	0.1454(9)
^117Sn	50	67	116.902952(3)	Stable[n 6]			1/2+	0.0768(7)
^117m1Sn	314.58(4) keV			13.76(4) d	IT	^117Sn	11/2−
^117m2Sn	2406.4(4) keV			1.75(7) µs			(19/2+)
^118Sn	50	68	117.901603(3)	Stable[n 6]			0+	0.2422(9)
^119Sn	50	69	118.903308(3)	Stable[n 6]			1/2+	0.0859(4)
^119m1Sn	89.531(13) keV			293.1(7) d	IT	^119Sn	11/2−
^119m2Sn	2127.0(10) keV			9.6(12) µs			(19/2+)
^120Sn	50	70	119.9021947(27)	Stable[n 6]			0+	0.3258(9)
^120m1Sn	2481.63(6) keV			11.8(5) µs			(7−)
^120m2Sn	2902.22(22) keV			6.26(11) µs			(10+)#
^121Sn[n 7]	50	71	120.9042355(27)	27.03(4) h	β^−	^121Sb	3/2+
^121m1Sn	6.30(6) keV			43.9(5) y	IT (77.6%)	^121Sn	11/2−
					β^− (22.4%)	^121Sb
^121m2Sn	1998.8(9) keV			5.3(5) µs			(19/2+)#
^121m3Sn	2834.6(18) keV			0.167(25) µs			(27/2−)
^122Sn[n 7]	50	72	121.9034390(29)	Observationally Stable[n 8]			0+	0.0463(3)
^123Sn[n 7]	50	73	122.9057208(29)	129.2(4) d	β^−	^123Sb	11/2−
^123m1Sn	24.6(4) keV			40.06(1) min	β^−	^123Sb	3/2+
^123m2Sn	1945.0(10) keV			7.4(26) µs			(19/2+)
^123m3Sn	2153.0(12) keV			6 µs			(23/2+)
^123m4Sn	2713.0(14) keV			34 µs			(27/2−)
^124Sn[n 7]	50	74	123.9052739(15)	Observationally Stable[n 9]			0+	0.0579(5)
^124m1Sn	2204.622(23) keV			0.27(6) µs			5-
^124m2Sn	2325.01(4) keV			3.1(5) µs			7−
^124m3Sn	2656.6(5) keV			45(5) µs			(10+)#
^125Sn[n 7]	50	75	124.9077841(16)	9.64(3) d	β^−	^125Sb	11/2−
^125mSn	27.50(14) keV			9.52(5) min			3/2+
^126Sn[n 10]	50	76	125.907653(11)	2.30(14)×10^5 y	β^− (66.5%)	^126m2Sb	0+
					β^− (33.5%)	^126m1Sb
^126m1Sn	2218.99(8) keV			6.6(14) µs			7−
^126m2Sn	2564.5(5) keV			7.7(5) µs			(10+)#
^127Sn	50	77	126.910360(26)	2.10(4) h	β^−	^127Sb	(11/2−)
^127mSn	4.7(3) keV			4.13(3) min	β^−	^127Sb	(3/2+)
^128Sn	50	78	127.910537(29)	59.07(14) min	β^−	^128Sb	0+
^128mSn	2091.50(11) keV			6.5(5) s	IT	^128Sn	(7−)
^129Sn	50	79	128.91348(3)	2.23(4) min	β^−	^129Sb	(3/2+)#
^129mSn	35.2(3) keV			6.9(1) min	β^− (99.99%)	^129Sb	(11/2−)#
					IT (.002%)	^129Sn
^130Sn	50	80	129.913967(11)	3.72(7) min	β^−	^130Sb	0+
^130m1Sn	1946.88(10) keV			1.7(1) min	β^−	^130Sb	(7−)#
^130m2Sn	2434.79(12) keV			1.61(15) µs			(10+)
^131Sn	50	81	130.917000(23)	56.0(5) s	β^−	^131Sb	(3/2+)
^131m1Sn	80(30)# keV			58.4(5) s	β^− (99.99%)	^131Sb	(11/2−)
					IT (.0004%)	^131Sn
^131m2Sn	4846.7(9) keV			300(20) ns			(19/2− to 23/2−)
^132Sn	50	82	131.917816(15)	39.7(8) s	β^−	^132Sb	0+
^133Sn	50	83	132.92383(4)	1.45(3) s	β^− (99.97%)	^133Sb	(7/2−)#
					β^−, n (.0294%)	^132Sb
^134Sn	50	84	133.92829(11)	1.050(11) s	β^− (83%)	^134Sb	0+
					β^−, n (17%)	^133Sb
^135Sn	50	85	134.93473(43)#	530(20) ms	β^−	^135Sb	(7/2−)
					β^−, n	^134Sb
^136Sn	50	86	135.93934(54)#	0.25(3) s	β^−	^136Sb	0+
					β^−, n	^135Sb
^137Sn	50	87	136.94599(64)#	190(60) ms	β^−	^137Sb	5/2−#

1. Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
2. Bold for stable isotopes
3. Heaviest known nuclide with more protons than neutrons
4. Heaviest known nuclide with equal numbers of protons and neutrons
5. Believed to decay by β⁺β⁺ to ¹¹²Cd
6. Theoretically capable of spontaneous fission
7. Fission product
8. Believed to undergo β⁻β⁻ decay to ¹²²Te
9. Believed to undergo β⁻β⁻ decay to ¹²⁴Te with a half-life over 100×10¹⁵ years
10. Long-lived fission product

Notes

• Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
• 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.

References

1. K. Sümmerer; R. Schneider; T Faestermann; J. Friese; H. Geissel; R. Gernhäuser; H. Gilg,; F. Heine; J. Homolka; P. Kienle; H. J. Körner; G. Münzenberg; J. Reinhold; K. Zeitelhack (April 1997). "Identification and decay spectroscopy of ¹⁰⁰Sn at the GSI projectile fragment separator FRS". Nuclear Physics A 616 (1–2): 341–345. doi:10.1016/S0375-9474(97)00106-1.
2. M. B. Chadwick et al, "ENDF/B-VII.1: Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data", Nucl. Data Sheets 112(2011)2887. (accessed at www-nds.iaea.org/exfor/endf.htm)
3. "Universal Nuclide Chart". nucleonica. (registration required (help)).

• 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.
• 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.
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005.
  • 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.