Isotopes of antimony

Short description: Nuclides with atomic number of 51 but with different mass numbers

Antimony (₅₁Sb) occurs in two stable isotopes, ¹²¹Sb and ¹²³Sb. There are 35 artificial radioactive isotopes, the longest-lived of which are ¹²⁵Sb, with a half-life of 2.75856 years; ¹²⁴Sb, with a half-life of 60.2 days; and ¹²⁶Sb, with a half-life of 12.35 days. All other isotopes have half-lives less than 4 days, most less than an hour.

There are also many isomers, the longest-lived of which is ^120m1Sb with a half-life of 5.76 days.

With the exception of beryllium, antimony is the lightest element observed to have isotopes capable of undergoing alpha decay, with the isotope ¹⁰⁴Sb being seen to undergo this mode of decay. Some lighter elements, namely those in the vicinity of ⁸Be, have isotopes with delayed alpha emission (following proton or beta emission) as a rare branch.

List of isotopes

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Nuclide ^{[n 1]}	Z	N	Isotopic mass (u) ^{[n 2]}^{[n 3]}	Half-life	Decay mode ^{[n 4]}	Daughter isotope ^{[n 5]}^{[n 6]}	Spin and parity ^{[n 7]}^{[n 8]}	Physics:Natural abundance (mole fraction)
Nuclide ^{[n 1]}	Excitation energy^{[n 8]}			Half-life	Decay mode ^{[n 4]}	Daughter isotope ^{[n 5]}^{[n 6]}	Spin and parity ^{[n 7]}^{[n 8]}	Normal proportion	Range of variation
¹⁰³Sb	51	52	102.93969(32)#	100# ms [>1.5 µs]	β⁺	¹⁰³Sn	5/2+#
¹⁰⁴Sb	51	53	103.93647(39)#	0.47(13) s [0.44(+15−11) s]	β⁺ (86%)	¹⁰⁴Sn
					p (7%)	¹⁰³Sn
					β⁺, p (7%)	¹⁰³In
					α (<1%)	¹⁰⁰In
¹⁰⁵Sb	51	54	104.93149(11)	1.12(16) s	β⁺ (99%)	¹⁰⁵Sn	(5/2+)
					p (1%)	¹⁰⁴Sn
					β⁺, p (<1%)	¹⁰⁴In
¹⁰⁶Sb	51	55	105.92879(34)#	0.6(2) s	β⁺	¹⁰⁶Sn	(4+)
^106mSb	1000(500)# keV			220(20) ns
¹⁰⁷Sb	51	56	106.92415(32)#	4.0(2) s	β⁺	¹⁰⁷Sn	5/2+#
¹⁰⁸Sb	51	57	107.92216(22)#	7.4(3) s	β⁺	¹⁰⁸Sn	(4+)
¹⁰⁸Sb	51	57	107.92216(22)#	7.4(3) s	β⁺, p (rare)	¹⁰⁷In	(4+)
¹⁰⁹Sb	51	58	108.918132(20)	17.3(5) s	β⁺	¹⁰⁹Sn	5/2+#
¹¹⁰Sb	51	59	109.91675(22)#	23.0(4) s	β⁺	¹¹⁰Sn	(4+)
¹¹¹Sb	51	60	110.91316(3)	75(1) s	β⁺	¹¹¹Sn	(5/2+)
¹¹²Sb	51	61	111.912398(19)	51.4(10) s	β⁺	¹¹²Sn	3+
¹¹³Sb	51	62	112.909372(19)	6.67(7) min	β⁺	¹¹³Sn	5/2+
¹¹⁴Sb	51	63	113.90927(3)	3.49(3) min	β⁺	¹¹⁴Sn	(3+)
^114mSb	495.5(7) keV			219(12) µs			(8−)
¹¹⁵Sb	51	64	114.906598(17)	32.1(3) min	β⁺	¹¹⁵Sn	5/2+
¹¹⁶Sb	51	65	115.906794(6)	15.8(8) min	β⁺	¹¹⁶Sn	3+
^116m1Sb	93.99(5) keV			194(4) ns			1+
^116m2Sb	380(40) keV			60.3(6) min	β⁺	¹¹⁶Sn	8−
¹¹⁷Sb	51	66	116.904836(10)	2.80(1) h	β⁺	¹¹⁷Sn	5/2+
¹¹⁸Sb	51	67	117.905529(4)	3.6(1) min	β⁺	¹¹⁸Sn	1+
^118m1Sb	50.814(21) keV			20.6(6) µs			(3)+
^118m2Sb	250(6) keV			5.00(2) h	β⁺	¹¹⁸Sn	8−
¹¹⁹Sb	51	68	118.903942(9)	38.19(22) h	EC	¹¹⁹Sn	5/2+
^119m1Sb	2553.6(3) keV			130(3) ns			(19/2−)
^119m2Sb	2852(7) keV			850(90) ms	IT	¹¹⁹Sb	27/2+#
¹²⁰Sb	51	69	119.905072(8)	15.89(4) min	β⁺	¹²⁰Sn	1+
^120m1Sb	0(100)# keV			5.76(2) d	β⁺	¹²⁰Sn	8−
^120m2Sb	78.16(5) keV			246(2) ns			(3+)
^120m3Sb	2328.3(6) keV			400(8) ns			(6)
¹²¹Sb^{[n 9]}	51	70	120.9038157(24)	Stable			5/2+	0.5721(5)
¹²²Sb	51	71	121.9051737(24)	2.7238(2) d	β⁻ (97.59%)	¹²²Te	2−
¹²²Sb	51	71	121.9051737(24)	2.7238(2) d	β⁺ (2.41%)	¹²²Sn	2−
^122m1Sb	61.4131(5) keV			1.86(8) µs			3+
^122m2Sb	137.4726(8) keV			0.53(3) ms			(5)+
^122m3Sb	163.5591(17) keV			4.191(3) min	IT	¹²²Sb	(8)−
¹²³Sb^{[n 9]}	51	72	122.9042140(22)	Stable			7/2+	0.4279(5)
¹²⁴Sb	51	73	123.9059357(22)	60.20(3) d	β⁻	¹²⁴Te	3−
^124m1Sb	10.8627(8) keV			93(5) s	IT (75%)	¹²⁴Sb	5+
^124m1Sb	10.8627(8) keV			93(5) s	β⁻ (25%)	¹²⁴Te	5+
^124m2Sb	36.8440(14) keV			20.2(2) min			(8)−
^124m3Sb	40.8038(7) keV			3.2(3) µs			(3+, 4+)
¹²⁵Sb	51	74	124.9052538(28)	2.75856(25) y	β⁻	^125mTe	7/2+
¹²⁶Sb	51	75	125.90725(3)	12.35(6) d	β⁻	¹²⁶Te	(8−)
^126m1Sb	17.7(3) keV			19.15(8) min	β⁻ (86%)	¹²⁶Te	(5+)
^126m1Sb	17.7(3) keV			19.15(8) min	IT (14%)	¹²⁶Sb	(5+)
^126m2Sb	40.4(3) keV			~11 s	IT	^126m1Sb	(3−)
^126m3Sb	104.6(3) keV			553(5) ns			(3+)
¹²⁷Sb	51	76	126.906924(6)	3.85(5) d	β⁻	^127mTe	7/2+
¹²⁸Sb	51	77	127.909169(27)	9.01(4) h	β⁻	¹²⁸Te	8−
^128mSb	10(7) keV			10.4(2) min	β⁻ (96.4%)	¹²⁸Te	5+
^128mSb	10(7) keV			10.4(2) min	IT (3.6%)	¹²⁸Sb	5+
¹²⁹Sb	51	78	128.909148(23)	4.40(1) h	β⁻	^129mTe	7/2+
^129m1Sb	1851.05(10) keV			17.7(1) min	β⁻ (85%)	¹²⁹Te	(19/2−)
^129m1Sb	1851.05(10) keV			17.7(1) min	IT (15%)	¹²⁹Sb	(19/2−)
^129m2Sb	1860.90(10) keV			>2 µs			(15/2−)
^129m3Sb	2138.9(5) keV			1.1(1) µs			(23/2+)
¹³⁰Sb	51	79	129.911656(18)	39.5(8) min	β⁻	¹³⁰Te	(8−)#
^130mSb	4.80(20) keV			6.3(2) min	β⁻	¹³⁰Te	(4, 5)+
¹³¹Sb	51	80	130.911982(22)	23.03(4) min	β⁻	^131mTe	(7/2+)
¹³²Sb	51	81	131.914467(15)	2.79(5) min	β⁻	¹³²Te	(4+)
^132m1Sb	200(30) keV			4.15(5) min	β⁻	¹³²Te	(8−)
^132m2Sb	254.5(3) keV			102(4) ns			(6−)
¹³³Sb	51	82	132.915252(27)	2.5(1) min	β⁻	^133mTe	(7/2+)
¹³⁴Sb	51	83	133.92038(5)	0.78(6) s	β⁻	¹³⁴Te	(0-)
^134mSb	80(110) keV			10.07(5) s	β⁻ (99.9%)	¹³⁴Te	(7−)
^134mSb	80(110) keV			10.07(5) s	β⁻, n (.091%)	¹³³Te	(7−)
¹³⁵Sb	51	84	134.92517(11)	1.68(2) s	β⁻ (82.4%)	¹³⁵Te	(7/2+)
¹³⁵Sb	51	84	134.92517(11)	1.68(2) s	β⁻, n (17.6%)	¹³⁴Te	(7/2+)
¹³⁶Sb	51	85	135.93035(32)#	0.923(14) s	β⁻ (83%)	¹³⁶Te	1−#
¹³⁶Sb	51	85	135.93035(32)#	0.923(14) s	β⁻, n (17%)	¹³⁵Te	1−#
^136mSb	173(3) keV			570(50) ns			6−#
¹³⁷Sb	51	86	136.93531(43)#	450(50) ms	β⁻	¹³⁷Te	7/2+#
¹³⁷Sb	51	86	136.93531(43)#	450(50) ms	β⁻, n	¹³⁶Te	7/2+#
¹³⁸Sb	51	87	137.94079(32)#	500# ms [>300 ns]	β⁻	¹³⁸Te	2−#
¹³⁸Sb	51	87	137.94079(32)#	500# ms [>300 ns]	β⁻, n	¹³⁷Te	2−#
¹³⁹Sb	51	88	138.94598(54)#	300# ms [>300 ns]	β⁻	¹³⁹Te	7/2+#

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

EC: Electron capture

IT: Isomeric transition

n: Neutron emission

p: Proton emission
↑ Bold italics symbol as daughter – Daughter product is nearly stable.
↑ Bold symbol as daughter – Daughter product is stable.
↑ ( ) spin value – Indicates spin with weak assignment arguments.
↑ ^8.0 ^8.1 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
↑ ^9.0 ^9.1 Fission product