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