# Isotopes of antimony

Antimony ($_{51}$Sb) occurs in two stable isotopes, $^{121}$Sb and $^{123}$Sb. There are 37 artificial radioactive isotopes, the longest-lived of which are $^{125}$Sb, with a half-life of 2.75856 years; $^{124}$Sb, with half-life 60.2 days; and $^{126}$Sb, with half-life 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 $^{120m1}$Sb with half-life 5.76 days.
Except for beryllium, antimony is the lightest element observed to have isotopes capable of alpha decay; $^{104}$Sb is seen to undergo this mode of decay. Some light elements, namely those near $^8$Be, have isotopes with delayed alpha emission (following proton or beta emission) as a rare branch.

## List of isotopes

| Nuclide | Z | N | Isotopic mass (Da) | Half-life | Decay mode | Daughter isotope | Spin and parity | Natural abundance (mole fraction) | Natural abundance (mole fraction) |
| Nuclide | Excitation energy | Excitation energy | Excitation energy | Half-life | Decay mode | Daughter isotope | Spin and parity | Normal proportion | Range of variation |
| $^{104}$Sb | 51 | 53 | 103.93634(11)# | 470(130) ms | β$^+$? | $^{104}$Sn | | | |
| $^{104}$Sb | 51 | 53 | 103.93634(11)# | 470(130) ms | p (<7%) | $^{103}$Sn | | | |
| $^{104}$Sb | 51 | 53 | 103.93634(11)# | 470(130) ms | β$^+$, p (<7%) | $^{103}$In | | | |
| $^{104}$Sb | 51 | 53 | 103.93634(11)# | 470(130) ms | α? | $^{100}$In | | | |
| $^{105}$Sb | 51 | 54 | 104.931277(23) | 1.12(16) s | β$^+$ (>99.9%) | $^{105}$Sn | (5/2+) | | |
| $^{105}$Sb | 51 | 54 | 104.931277(23) | 1.12(16) s | p (<0.1%) | $^{104}$Sn | (5/2+) | | |
| $^{105}$Sb | 51 | 54 | 104.931277(23) | 1.12(16) s | β$^+$, p? | $^{104}$In | (5/2+) | | |
| $^{106}$Sb | 51 | 55 | 105.9286380(80) | 0.6(2) s | β$^+$ | $^{106}$Sn | (2+) | | |
| $^{106m}$Sb | 103.5(3) keV | 103.5(3) keV | 103.5(3) keV | 226(14) ns | IT | $^{106}$Sb | (4+) | | |
| $^{107}$Sb | 51 | 56 | 106.9241506(45) | 4.0(2) s | β$^+$ | $^{107}$Sn | 5/2+# | | |
| $^{108}$Sb | 51 | 57 | 107.9222267(59) | 7.4(3) s | β$^+$ | $^{108}$Sn | (4+) | | |
| $^{109}$Sb | 51 | 58 | 108.9181412(57) | 17.2(5) s | β$^+$ | $^{109}$Sn | 5/2+# | | |
| $^{110}$Sb | 51 | 59 | 109.9168543(64) | 23.6(3) s | β$^+$ | $^{110}$Sn | (3+) | | |
| $^{111}$Sb | 51 | 60 | 110.9132182(95) | 75(1) s | β$^+$ | $^{111}$Sn | (5/2+) | | |
| $^{112}$Sb | 51 | 61 | 111.912400(19) | 53.5(6) s | β$^+$ | $^{112}$Sn | (3+) | | |
| $^{112m}$Sb | 825.9(4) keV | 825.9(4) keV | 825.9(4) keV | 536(22) ns | IT | $^{112}$Sb | (8−) | | |
| $^{113}$Sb | 51 | 62 | 112.909375(18) | 6.67(7) min | β$^+$ | $^{113}$Sn | 5/2+ | | |
| $^{114}$Sb | 51 | 63 | 113.909289(21) | 3.49(3) min | β$^+$ | $^{114}$Sn | 3+ | | |
| $^{114m}$Sb | 495.5(7) keV | 495.5(7) keV | 495.5(7) keV | 219(12) μs | IT | $^{114}$Sb | (8−) | | |
| $^{115}$Sb | 51 | 64 | 114.906598(17) | 32.1(3) min | β$^+$ | $^{115}$Sn | 5/2+ | | |
| $^{115m}$Sb | 2796.26(9) keV | 2796.26(9) keV | 2796.26(9) keV | 159(3) ns | IT | $^{115}$Sb | (19/2)− | | |
| $^{116}$Sb | 51 | 65 | 115.9067927(55) | 15.8(8) min | β$^+$ | $^{116}$Sn | 3+ | | |
| $^{116m1}$Sb | 93.99(5) keV | 93.99(5) keV | 93.99(5) keV | 194(4) ns | IT | $^{116}$Sb | 1+ | | |
| $^{116m2}$Sb | 390(40) keV | 390(40) keV | 390(40) keV | 60.3(6) min | β$^+$ | $^{116}$Sn | 8− | | |
| $^{117}$Sb | 51 | 66 | 116.9048415(91) | 2.97(2) h | β$^+$ | $^{117}$Sn | 5/2+ | | |
| $^{117m1}$Sb | 3130.76(19) keV | 3130.76(19) keV | 3130.76(19) keV | 355(17) μs | IT | $^{117}$Sb | (25/2)+ | | |
| $^{117m2}$Sb | 3230.7(2) keV | 3230.7(2) keV | 3230.7(2) keV | 290(5) ns | IT | $^{117}$Sb | (23/2−) | | |
| $^{118}$Sb | 51 | 67 | 117.9055322(32) | 3.6(1) min | β$^+$ | $^{118}$Sn | 1+ | | |
| $^{118m1}$Sb | 50.814(21) keV | 50.814(21) keV | 50.814(21) keV | 20.6(6) μs | IT | $^{118}$Sb | 3+ | | |
| $^{118m2}$Sb | 250(6) keV | 250(6) keV | 250(6) keV | 5.01(3) h | β$^+$ | $^{118}$Sn | 8− | | |
| $^{119}$Sb | 51 | 68 | 118.9039441(75) | 38.19(22) h | EC | $^{119}$Sn | 5/2+ | | |
| $^{119m1}$Sb | 2553.6(3) keV | 2553.6(3) keV | 2553.6(3) keV | 130(3) ns | IT | $^{119}$Sb | 19/2− | | |
| $^{119m2}$Sb | 2841.7(4) keV | 2841.7(4) keV | 2841.7(4) keV | 835(81) ms | IT | $^{119}$Sb | 25/2+ | | |
| $^{120}$Sb | 51 | 69 | 119.9050803(77) | 15.89(4) min | β$^+$ | $^{120}$Sn | 1+ | | |
| $^{120m1}$Sb | 0(100)# keV | 0(100)# keV | 0(100)# keV | 5.76(2) d | β$^+$ | $^{120}$Sn | 8− | | |
| $^{120m2}$Sb | 78.16(5) keV | 78.16(5) keV | 78.16(5) keV | 246(2) ns | IT | $^{120}$Sb | (3+) | | |
| $^{120m3}$Sb | 2328(100)# keV | 2328(100)# keV | 2328(100)# keV | 400(8) ns | IT | $^{120}$Sb | 13+ | | |
| $^{121}$Sb | 51 | 70 | 120.9038114(27) | Stable | Stable | Stable | 5/2+ | 0.5721(5) | |
| $^{121m}$Sb | 2751(17) keV | 2751(17) keV | 2751(17) keV | 179(6) μs | IT | $^{121}$Sb | (25/2+) | | |
| $^{122}$Sb | 51 | 71 | 121.9051693(27) | 2.7238(2) d | β$^−$ (97.59%) | $^{122}$Te | 2− | | |
| $^{122}$Sb | 51 | 71 | 121.9051693(27) | 2.7238(2) d | β$^+$ (2.41%) | $^{122}$Sn | 2− | | |
| $^{122m1}$Sb | 61.4131(5) keV | 61.4131(5) keV | 61.4131(5) keV | 1.86(8) μs | IT | $^{122}$Sb | 3+ | | |
| $^{122m2}$Sb | 137.4726(8) keV | 137.4726(8) keV | 137.4726(8) keV | 0.53(3) ms | IT | $^{122}$Sb | 5+ | | |
| $^{122m3}$Sb | 163.5591(17) keV | 163.5591(17) keV | 163.5591(17) keV | 4.191(3) min | IT | $^{122}$Sb | 8− | | |
| $^{123}$Sb | 51 | 72 | 122.9042153(15) | Stable | Stable | Stable | 7/2+ | 0.4279(5) | |
| $^{123m1}$Sb | 2237.8(3) keV | 2237.8(3) keV | 2237.8(3) keV | 214(3) ns | IT | $^{123}$Sb | 19/2− | | |
| $^{123m2}$Sb | 2613.4(4) keV | 2613.4(4) keV | 2613.4(4) keV | 65(1) μs | IT | $^{123}$Sb | 23/2+ | | |
| $^{124}$Sb | 51 | 73 | 123.9059371(15) | 60.20(3) d | β$^−$ | $^{124}$Te | 3− | | |
| $^{124m1}$Sb | 10.8627(8) keV | 10.8627(8) keV | 10.8627(8) keV | 93(5) s | IT (75%) | $^{124}$Sb | 5+ | | |
| $^{124m1}$Sb | 10.8627(8) keV | 10.8627(8) keV | 10.8627(8) keV | 93(5) s | β$^−$ (25%) | $^{124}$Te | 5+ | | |
| $^{124m2}$Sb | 36.8440(14) keV | 36.8440(14) keV | 36.8440(14) keV | 20.2(2) min | IT | $^{124m1}$Sb | (8)− | | |
| $^{124m3}$Sb | 40.8038(7) keV | 40.8038(7) keV | 40.8038(7) keV | 3.2(3) μs | IT | $^{124}$Sb | (3+) | | |
| $^{125}$Sb | 51 | 74 | 124.9052543(27) | 2.7576(11) y | β$^−$ | $^{125}$Te | 7/2+ | | |
| $^{125m1}$Sb | 1971.25(20) keV | 1971.25(20) keV | 1971.25(20) keV | 4.1(2) μs | IT | $^{125}$Sb | 15/2− | | |
| $^{125m2}$Sb | 2112.1(3) keV | 2112.1(3) keV | 2112.1(3) keV | 28.5(5) μs | IT | $^{125}$Sb | 19/2− | | |
| $^{125m3}$Sb | 2471.0(4) keV | 2471.0(4) keV | 2471.0(4) keV | 277.0(64) ns | IT | $^{125}$Sb | (23/2)+ | | |
| $^{126}$Sb | 51 | 75 | 125.907253(34) | 12.35(6) d | β$^−$ | $^{126}$Te | 8− | | |
| $^{126m1}$Sb | 17.7(3) keV | 17.7(3) keV | 17.7(3) keV | 19.15(8) min | β$^−$ (86%) | $^{126}$Te | 5+ | | |
| $^{126m1}$Sb | 17.7(3) keV | 17.7(3) keV | 17.7(3) keV | 19.15(8) min | IT (14%) | $^{126}$Sb | 5+ | | |
| $^{126m2}$Sb | 40.4(3) keV | 40.4(3) keV | 40.4(3) keV | ~11 s | IT | $^{126m1}$Sb | 3− | | |
| $^{126m3}$Sb | 104.6(3) keV | 104.6(3) keV | 104.6(3) keV | 553(5) ns | IT | $^{126}$Sb | 3+ | | |
| $^{126m4}$Sb | 1810.7(17) keV | 1810.7(17) keV | 1810.7(17) keV | 90(16) ns | IT | $^{126}$Sb | (13+) | | |
| $^{127}$Sb | 51 | 76 | 126.9069256(55) | 3.85(5) d | β$^−$ | $^{127}$Te | 7/2+ | | |
| $^{127m1}$Sb | 1920.19(21) keV | 1920.19(21) keV | 1920.19(21) keV | 11.7(1) μs | IT | $^{127}$Sb | 15/2− | | |
| $^{127m2}$Sb | 2324.7(4) keV | 2324.7(4) keV | 2324.7(4) keV | 269(5) ns | IT | $^{127}$Sb | 23/2+ | | |
| $^{128}$Sb | 51 | 77 | 127.909146(20) | 9.05(4) h | β$^−$ | $^{128}$Te | 8− | | |
| $^{128m1}$Sb | 10(6) keV | 10(6) keV | 10(6) keV | 10.41(18) min | β$^−$ (96.4%) | $^{128}$Te | 5+ | | |
| $^{128m1}$Sb | 10(6) keV | 10(6) keV | 10(6) keV | 10.41(18) min | IT (3.6%) | $^{128}$Sb | 5+ | | |
| $^{128m2}$Sb | 1617.3(7) keV | 1617.3(7) keV | 1617.3(7) keV | 500(20) ns | IT | $^{128}$Sb | (11+) | | |
| $^{128m3}$Sb | 1769.9(12) keV | 1769.9(12) keV | 1769.9(12) keV | 217(7) ns | IT | $^{128}$Sb | (13+) | | |
| $^{129}$Sb | 51 | 78 | 128.909147(23) | 4.366(26) h | β$^−$ | $^{129}$Te | 7/2+ | | |
| $^{129m1}$Sb | 1851.31(6) keV | 1851.31(6) keV | 1851.31(6) keV | 17.7(1) min | β$^−$ (85%) | $^{129}$Te | 19/2− | | |
| $^{129m1}$Sb | 1851.31(6) keV | 1851.31(6) keV | 1851.31(6) keV | 17.7(1) min | IT (15%) | $^{129}$Sb | 19/2− | | |
| $^{129m2}$Sb | 1861.06(5) keV | 1861.06(5) keV | 1861.06(5) keV | 2.23(17) μs | IT | $^{129}$Sb | 15/2− | | |
| $^{129m3}$Sb | 2139.4(3) keV | 2139.4(3) keV | 2139.4(3) keV | 0.89(3) μs | IT | $^{129}$Sb | 23/2+ | | |
| $^{130}$Sb | 51 | 79 | 129.911663(15) | 39.5(8) min | β$^−$ | $^{130}$Te | 8− | | |
| $^{130m1}$Sb | 4.80(20) keV | 4.80(20) keV | 4.80(20) keV | 6.3(2) min | β$^−$ | $^{130}$Te | 4+ | | |
| $^{130m2}$Sb | 84.67(4) keV | 84.67(4) keV | 84.67(4) keV | 800(100) ns | IT | $^{130}$Sb | 6− | | |
| $^{130m3}$Sb | 1508(1) keV | 1508(1) keV | 1508(1) keV | 600(15) ns | IT | $^{130}$Sb | (11+) | | |
| $^{130m4}$Sb | 1544.7(5) keV | 1544.7(5) keV | 1544.7(5) keV | 1.25(1) μs | IT | $^{130}$Sb | (13+) | | |
| $^{131}$Sb | 51 | 80 | 130.9119893(22) | 23.03(4) min | β$^−$ | $^{131}$Te | 7/2+ | | |
| $^{131m1}$Sb | 1676.06(6) keV | 1676.06(6) keV | 1676.06(6) keV | 64.2(26) μs | IT | $^{131}$Sb | 15/2− | | |
| $^{131m2}$Sb | 1687.2(9) keV | 1687.2(9) keV | 1687.2(9) keV | 4.3(8) μs | IT | $^{131}$Sb | 19/2− | | |
| $^{131m3}$Sb | 2165.6(15) keV | 2165.6(15) keV | 2165.6(15) keV | 0.97(3) μs | IT | $^{131}$Sb | 23/2+ | | |
| $^{132}$Sb | 51 | 81 | 131.9145141(29) | 2.79(7) min | β$^−$ | $^{132}$Te | (4)+ | | |
| $^{132m1}$Sb | 139.3(20) keV | 139.3(20) keV | 139.3(20) keV | 4.10(5) min | β$^−$ | $^{132}$Te | (8−) | | |
| $^{132m2}$Sb | 254.5(3) keV | 254.5(3) keV | 254.5(3) keV | 102(4) ns | IT | $^{132}$Sb | (6−) | | |
| $^{133}$Sb | 51 | 82 | 132.9152721(34) | 2.34(5) min | β$^−$ | $^{133}$Te | (7/2+) | | |
| $^{133m}$Sb | 4541(9) keV | 4541(9) keV | 4541(9) keV | 16.54(19) μs | IT | $^{133}$Sb | (21/2+) | | |
| $^{134}$Sb | 51 | 83 | 133.9205373(33) | 674(4) ms | β$^−$ | $^{134}$Te | (0-) | | |
| $^{134}$Sb | 51 | 83 | 133.9205373(33) | 674(4) ms | β$^−$, n? | $^{133}$Te | (0-) | | |
| $^{134m}$Sb | 279(1) keV | 279(1) keV | 279(1) keV | 10.01(4) s | β$^−$ (99.91%) | $^{134}$Te | (7−) | | |
| $^{134m}$Sb | 279(1) keV | 279(1) keV | 279(1) keV | 10.01(4) s | β$^−$, n (0.088%) | $^{133}$Te | (7−) | | |
| $^{135}$Sb | 51 | 84 | 134.9251844(28) | 1.668(9) s | β$^−$ (80.9%) | $^{135}$Te | (7/2+) | | |
| $^{135}$Sb | 51 | 84 | 134.9251844(28) | 1.668(9) s | β$^−$, n (19.1%) | $^{134}$Te | (7/2+) | | |
| $^{136}$Sb | 51 | 85 | 135.9307490(63) | 0.923(14) s | β$^−$ (75.2%) | $^{136}$Te | (1−) | | |
| $^{136}$Sb | 51 | 85 | 135.9307490(63) | 0.923(14) s | β$^−$, n (24.7%) | $^{135}$Te | (1−) | | |
| $^{136}$Sb | 51 | 85 | 135.9307490(63) | 0.923(14) s | β$^−$, 2n (0.14%) | $^{134}$Te | (1−) | | |
| $^{136m}$Sb | 269.3(5) keV | 269.3(5) keV | 269.3(5) keV | 570(5) ns | IT | $^{136}$Sb | (6−) | | |
| $^{137}$Sb | 51 | 86 | 136.935523(56) | 497(21) ms | β$^−$ (51%) | $^{137}$Te | 7/2+# | | |
| $^{137}$Sb | 51 | 86 | 136.935523(56) | 497(21) ms | β$^−$, n (49%) | $^{136}$Te | 7/2+# | | |
| $^{137}$Sb | 51 | 86 | 136.935523(56) | 497(21) ms | β$^−$, 2n? | $^{135}$Te | 7/2+# | | |
| $^{138}$Sb | 51 | 87 | 137.94133(32)# | 333(7) ms | β$^−$, n (72%) | $^{137}$Te | (3−) | | |
| $^{138}$Sb | 51 | 87 | 137.94133(32)# | 333(7) ms | β$^−$ (28%) | $^{138}$Te | (3−) | | |
| $^{138}$Sb | 51 | 87 | 137.94133(32)# | 333(7) ms | β$^−$, 2n? | $^{136}$Te | (3−) | | |
| $^{139}$Sb | 51 | 88 | 138.94627(43)# | 182(9) ms | β$^−$, n (90%) | $^{138}$Te | 7/2+# | | |
| $^{139}$Sb | 51 | 88 | 138.94627(43)# | 182(9) ms | β$^−$ (10%) | $^{139}$Te | 7/2+# | | |
| $^{139}$Sb | 51 | 88 | 138.94627(43)# | 182(9) ms | β$^−$, 2n? | $^{137}$Te | 7/2+# | | |
| $^{140}$Sb | 51 | 89 | 139.95235(64)# | 170(6) ms | β$^−$ (69%) | $^{140}$Te | (3−) | | |
| $^{140}$Sb | 51 | 89 | 139.95235(64)# | 170(6) ms | β$^−$, n (23%) | $^{139}$Te | (3−) | | |
| $^{140}$Sb | 51 | 89 | 139.95235(64)# | 170(6) ms | β$^−$, 2n (7.6%) | $^{138}$Te | (3−) | | |
| $^{140m}$Sb | 330(30)# keV | 330(30)# keV | 330(30)# keV | 41(8) μs | IT | $^{140}$Sb | (6−,7−) | | |
| $^{141}$Sb | 51 | 90 | 140.95755(54)# | 103(29) ms | β$^−$ | $^{141}$Te | 7/2+# | | |
| $^{141}$Sb | 51 | 90 | 140.95755(54)# | 103(29) ms | β$^−$, n? | $^{140}$Te | 7/2+# | | |
| $^{141}$Sb | 51 | 90 | 140.95755(54)# | 103(29) ms | β$^−$, 2n? | $^{139}$Te | 7/2+# | | |
| $^{142}$Sb | 51 | 91 | 141.96392(32)# | 80(50) ms | β$^−$ | $^{142}$Te | | | |
| $^{142}$Sb | 51 | 91 | 141.96392(32)# | 80(50) ms | β$^−$, n? | $^{141}$Te | | | |
| $^{142}$Sb | 51 | 91 | 141.96392(32)# | 80(50) ms | β$^−$, 2n? | $^{140}$Te | | | |
| This table header & footer: view ||||||||||
* ↑ $^m$Sb – 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.
* 1 2 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
* 1 2 Order of ground state and isomer is uncertain.
* 1 2 Fission product