Isotopes of tin

Tin (₅₀Sn) 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. Twenty-nine additional unstable isotopes are known, including the "doubly magic" tin-100 (¹⁰⁰Sn) (discovered in 1994)[2] 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.

Main isotopes of tin (₅₀Sn)

Iso­tope Decay abun­dance half-life (t1/2) mode pro­duct ^112Sn 0.97% stable ^114Sn 0.66% stable ^115Sn 0.34% stable ^116Sn 14.54% stable ^117Sn 7.68% stable ^118Sn 24.22% stable ^119Sn 8.59% stable ^120Sn 32.58% stable ^122Sn 4.63% stable ^124Sn 5.79% stable ^126Sn trace 2.3×10^5 y β^− ^126Sb
Standard atomic weight Ar, standard(Sn)	118.710(7)[1]

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da) [n 2][n 3]	Half-life [n 4]	Decay mode [n 5]	Daughter isotope [n 6]	Spin and parity [n 7][n 4]	Natural abundance (mole fraction)
	Excitation energy[n 4]							Normal proportion	Range of variation
^99Sn[n 8]	50	49	98.94933(64)#	5# ms			9/2+#
^100Sn	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 9]			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			0+	0.0066(1)
^114mSn	3087.37(7) keV			733(14) ns			7−
^115Sn	50	65	114.903342(3)	Stable			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			0+	0.1454(9)
^117Sn	50	67	116.902952(3)	Stable			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			0+	0.2422(9)
^119Sn	50	69	118.903308(3)	Stable			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			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 10]	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 10]	50	72	121.9034390(29)	Observationally Stable[n 11]			0+	0.0463(3)
^123Sn[n 10]	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 10]	50	74	123.9052739(15)	Observationally Stable[n 12]			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 10]	50	75	124.9077841(16)	9.64(3) d	β^−	^125Sb	11/2−
^125mSn	27.50(14) keV			9.52(5) min	β^−	^125Sb	3/2+
^126Sn[n 13]	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−#
^138Sn	50	88	137.951840(540)#	140 ms +30-20	β^−	^138Sb
^138mSn	1344(2) keV			210(45) ns
^139Sn	50	89	137.951840(540)#	130 ms	β^−	^139Sb

1. ^mSn – Excited nuclear isomer.
2. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
3. # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
4. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
5. Modes of decay:

   EC:	Electron capture
   IT:	Isomeric transition
   n:	Neutron emission
   p:	Proton emission

6. Bold symbol as daughter – Daughter product is stable.
7. ( ) spin value – Indicates spin with weak assignment arguments.
8. Heaviest known nuclide with more protons than neutrons
9. Believed to decay by β⁺β⁺ to ¹¹²Cd
10. Fission product
11. Believed to undergo β⁻β⁻ decay to ¹²²Te
12. Believed to undergo β⁻β⁻ decay to ¹²⁴Te with a half-life over 100×10¹⁵ years
13. Long-lived fission product

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.[3]

Tin-126

Yield, % per fission[3]

	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 seven long-lived fission products. While tin-126's half-life of 230,000 years translates to a low specific activity of gamma radiation, its short-lived decay products, two isomers of antimony-126, emit 17 and 40 keV gamma radiation and a 3.67 MeV beta particle on their way to stable tellurium-126, 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 such as californium, will produce it at higher yields.

• ANL factsheet

References

1. Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
2. 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. Bibcode:1997NuPhA.616..341S. doi:10.1016/S0375-9474(97)00106-1.
3. M. B. Chadwick et al, "Evaluated Nuclear Data File (ENDF) : 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 https://www-nds.iaea.org/exfor/endf.htm)

• Isotope masses from:
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", 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:
  • de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
  • Wieser, Michael E. (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:
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  • National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  • Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.