Natural yttrium (39Y) is composed of a single isotope yttrium-89. The most stable radioisotopes are 88Y, which has a half-life of 106.6 days, and 91Y, with a half-life of 58.51 days. All the other isotopes have half-lives of less than a day, except 87Y, which has a half-life of 79.8 hours, and 90Y, with 64 hours. The dominant decay mode below the stable 89Y is electron capture and the dominant mode after it is beta emission. Thirty-five unstable isotopes have been characterized.
90Y exists in equilibrium with its parent isotope strontium-90, which is a product of nuclear fission.
|-id=Yttrium-76| rowspan=3|76Y| rowspan=3 style="text-align:right" | 39| rowspan=3 style="text-align:right" | 37| rowspan=3|75.95894(32)#| rowspan=3|28(9) ms| β+?| 76Sr| rowspan=3|1−#| rowspan=3||-| p?| 75Sr|-| β+, p?| 75Rb|-id=Yttrium-77| rowspan=3|77Y| rowspan=3 style="text-align:right" | 39| rowspan=3 style="text-align:right" | 38| rowspan=3|76.95015(22)#| rowspan=3|63(17) ms| β+| 77Sr| rowspan=3|5/2+#| rowspan=3||-| p?| 76Sr|-| β+, p?| 76Rb|-id=Yttrium-78| rowspan=2|78Y| rowspan=2 style="text-align:right" | 39| rowspan=2 style="text-align:right" | 39| rowspan=2|77.94399(32)#| rowspan=2|54(5) ms| β+| 78Sr| rowspan=2|(0+)| rowspan=2||-| β+, p?| 77Rb|-id=Yttrium-78m| rowspan=2 style="text-indent:1em" | 78mY[1] | rowspan=2 colspan="3" style="text-indent:2em" | 0(500)# keV| rowspan=2|5.8(6) s| β+| 78Sr| rowspan=2|(5+)| rowspan=2||-| β+, p?| 77Rb|-id=Yttrium-79| 79Y| style="text-align:right" | 39| style="text-align:right" | 40| 78.937946(86)| 14.8(6) s| β+| 79Sr| 5/2+#| |-id=Yttrium-80| 80Y| style="text-align:right" | 39| style="text-align:right" | 41| 79.9343548(67)| 30.1(5) s| β+| 80Sr| 4−||-id=Yttrium-80m1| rowspan=2 style="text-indent:1em" | 80m1Y| rowspan=2 colspan="3" style="text-indent:2em" | 228.5(1) keV| rowspan=2|4.8(3) s| IT (81%)| 80Y| rowspan=2|1−| rowspan=2||-| β+ (19%)| 80Sr|-id=Yttrium-80m2| style="text-indent:1em" | 80m2Y| colspan="3" style="text-indent:2em" | 312.6(9) keV| 4.7(3) μs| IT| 80Y| (2+)||-id=Yttrium-81| 81Y| style="text-align:right" | 39| style="text-align:right" | 42| 80.9294543(58)| 70.4(10) s| β+| 81Sr| (5/2+)||-id=Yttrium-82| 82Y| style="text-align:right" | 39| style="text-align:right" | 43| 81.9269302(59)| 8.30(20) s| β+| 82Sr| 1+||-id=Yttrium-82m1| style="text-indent:1em" | 82m1Y| colspan="3" style="text-indent:2em" | 402.63(14) keV| 258(22) ns| IT| 82Y| 4−||-id=Yttrium-82m2| style="text-indent:1em" | 82m2Y| colspan="3" style="text-indent:2em" | 507.50(13) keV| 148(6) ns| IT| 82Y| 6+||-id=Yttrium-83| 83Y| style="text-align:right" | 39| style="text-align:right" | 44| 82.922484(20)| 7.08(8) min| β+| 83Sr| (9/2+)||-id=Yttrium-83m| rowspan=2 style="text-indent:1em" | 83mY| rowspan=2 colspan="3" style="text-indent:2em" | 62.04(10) keV| rowspan=2|2.85(2) min| β+ (60%)| 83Sr| rowspan=2|(3/2−)| rowspan=2||-| IT (40%)| 83Y|-id=Yttrium-84| 84Y| style="text-align:right" | 39| style="text-align:right" | 45| 83.9206711(46)| 39.5(8) min| β+| 84Sr| (6+)||-id=Yttrium-84m1| style="text-indent:1em" | 84m1Y| colspan="3" style="text-indent:2em" | 67.0(2) keV| 4.6(2) s| β+| 84Sr| 1+||-id=Yttrium-84m2| style="text-indent:1em" | 84m2Y| colspan="3" style="text-indent:2em" | 210.42(16) keV| 292(10) ns| IT| 84Y| 4−||-id=Yttrium-85| 85Y| style="text-align:right" | 39| style="text-align:right" | 46| 84.916433(20)| 2.68(5) h| β+| 85Sr| (1/2)−||-id=Yttrium-85m1| rowspan=2 style="text-indent:1em" | 85m1Y| rowspan=2 colspan="3" style="text-indent:2em" | 19.68(17) keV| rowspan=2|4.86(20) h| β+| 85Sr| rowspan=2|(9/2)+| rowspan=2||-| IT?| 85Y|-id=Yttrium-85m2| style="text-indent:1em" | 85m2Y| colspan="3" style="text-indent:2em" | 266.18(10) keV| 178(7) ns| IT| 85Y| (5/2)−||-id=Yttrium-86| 86Y| style="text-align:right" | 39| style="text-align:right" | 47| 85.914886(15)| 14.74(2) h| β+| 86Sr| 4−||-id=Yttrium-86m1| rowspan=2 style="text-indent:1em" | 86m1Y| rowspan=2 colspan="3" style="text-indent:2em" | 218.21(9) keV| rowspan=2|47.4(4) min| IT (99.31%)| 86Y| rowspan=2|(8+)| rowspan=2||-| β+ (0.69%)| 86Sr|-id=Yttrium-86m2| style="text-indent:1em" | 86m2Y| colspan="3" style="text-indent:2em" | 302.18(9) keV| 125.3(55) ns| IT| 86Y| 6+||-id=Yttrium-87| 87Y| style="text-align:right" | 39| style="text-align:right" | 48| 86.9108761(12)| 79.8(3) h| β+| 87Sr| 1/2−||-id=Yttrium-87m| rowspan=2 style="text-indent:1em" | 87mY| rowspan=2 colspan="3" style="text-indent:2em" | 380.82(7) keV| rowspan=2|13.37(3) h| IT (98.43%)| 87Y| rowspan=2|9/2+| rowspan=2||-| β+ (1.57%)| 87Sr|-id=Yttrium-88| 88Y| style="text-align:right" | 39| style="text-align:right" | 49| 87.9095013(16)| 106.629(24) d| β+| 88Sr| 4−||-id=Yttrium-88m1| style="text-indent:1em" | 88m1Y| colspan="3" style="text-indent:2em" | 392.86(9) keV| 301(3) μs| IT| 88Y| 1+||-id=Yttrium-88m2| style="text-indent:1em" | 88m2Y| colspan="3" style="text-indent:2em" | 674.55(4) keV| 13.98(17) ms| IT| 88Y| 8+||-id=Yttrium-89| 89Y[2] | style="text-align:right" | 39| style="text-align:right" | 50| 88.90583816(36)| colspan=3 align=center|Stable| 1/2−| 1.0000|-id=Yttrium-89m| style="text-indent:1em" | 89mY| colspan="3" style="text-indent:2em" | 908.97(3) keV| 15.663(5) s| IT| 89Y| 9/2+||-| 90Y| style="text-align:right" | 39| style="text-align:right" | 51| 89.90714175(38)| 64.05(5) h| β−| 90Zr| 2−||-id=Yttrium-90m| rowspan=2 style="text-indent:1em" | 90mY| rowspan=2 colspan="3" style="text-indent:2em" | 682.01(5) keV| rowspan=2|3.226(11) h| IT| 90Y| rowspan=2|7+| rowspan=2||-| β− (0.0018%)| 90Zr|-id=Yttrium-91| 91Y| style="text-align:right" | 39| style="text-align:right" | 52| 90.9072980(20)| 58.51(6) d| β−| 91Zr| 1/2−||-id=Yttrium-91m| rowspan=2 style="text-indent:1em" | 91mY| rowspan=2 colspan="3" style="text-indent:2em" | 555.58(5) keV| rowspan=2|49.71(4) min| IT| 91Y| rowspan=2|9/2+| rowspan=2||-| β−?| 91Zr|-id=Yttrium-92| 92Y| style="text-align:right" | 39| style="text-align:right" | 53| 91.9089458(98)| 3.54(1) h| β−| 92Zr| 2−||-id=Yttrium-92m| style="text-indent:1em" | 92mY| colspan="3" style="text-indent:2em" | 807(50)# keV| 3.7(5) μs| IT| 92Y| 7+#||-id=Yttrium-93| 93Y| style="text-align:right" | 39| style="text-align:right" | 54| 92.909578(11)| 10.18(8) h| β−| 93Zr| 1/2−||-id=Yttrium-93m| style="text-indent:1em" | 93mY| colspan="3" style="text-indent:2em" | 758.719(21) keV| 820(40) ms| IT| 93Y| 9/2+||-id=Yttrium-94| 94Y| style="text-align:right" | 39| style="text-align:right" | 55| 93.9115921(68)| 18.7(1) min| β−| 94Zr| 2−||-id=Yttrium-94m| style="text-indent:1em" | 94mY| colspan="3" style="text-indent:2em" | 1202.3(10) keV| 1.304(12) μs| IT| 94Y| (5+)||-id=Yttrium-95| 95Y| style="text-align:right" | 39| style="text-align:right" | 56| 94.9128197(73)| 10.3(1) min| β−| 95Zr| 1/2−||-id=Yttrium-95m| style="text-indent:1em" | 95mY| colspan="3" style="text-indent:2em" | 1087.6(6) keV| 48.6(5) μs| IT| 95Y| 9/2+||-id=Yttrium-96| 96Y| style="text-align:right" | 39| style="text-align:right" | 57| 95.9159093(65)| 5.34(5) s| β−| 96Zr| 0−||-id=Yttrium-96m1| style="text-indent:1em" | 96m1Y| colspan="3" style="text-indent:2em" | 1540(9) keV| 9.6(2) s| β−| 96Zr| 8+||-id=Yttrium-96m2| style="text-indent:1em" | 96m2Y| colspan="3" style="text-indent:2em" | 1655.0(11) keV| 181(9) ns| IT| 96Y| (6+)||-id=Yttrium-97| rowspan=2|97Y| rowspan=2 style="text-align:right" | 39| rowspan=2 style="text-align:right" | 58| rowspan=2|96.9182867(72)| rowspan=2|3.75(3) s| β− (99.945%)| 97Zr| rowspan=2|1/2−| rowspan=2||-| β−, n (0.055%)| 96Zr|-id=Yttrium-97m1| rowspan=3 style="text-indent:1em" | 97m1Y| rowspan=3 colspan="3" style="text-indent:2em" | 667.52(23) keV| rowspan=3|1.17(3) s| β− (>99.2%)| 97Zr| rowspan=3|9/2+| rowspan=3||-| IT (<0.7%)| 97Y|-| β−, n (0.11%)| 96Zr|-id=Yttrium-97m2| rowspan=2 style="text-indent:1em" | 97m2Y| rowspan=2 colspan="3" style="text-indent:2em" | 3522.6(4) keV| rowspan=2|142(8) ms| IT (94.8%)| 97Y| rowspan=2|(27/2−)| rowspan=2||-| β− (5.2%)| 97Zr|-id=Yttrium-98| rowspan=2|98Y| rowspan=2 style="text-align:right" | 39| rowspan=2 style="text-align:right" | 59| rowspan=2|97.9223948(85)| rowspan=2|548(2) ms| β− (99.67%)| 98Zr| rowspan=2|0−| rowspan=2||-| β−, n (0.33%)| 97Zr|-id=Yttrium-98m1| style="text-indent:1em" | 98m1Y| colspan="3" style="text-indent:2em" | 170.78(5) keV| 615(8) ns| IT| 98Y| 2−| |-id=Yttrium-98m2| rowspan=3 style="text-indent:1em" | 98m2Y| rowspan=3 colspan="3" style="text-indent:2em" | 465.7(7) keV| rowspan=3|2.32(8) s| β− (96.56%)| 98Zr| rowspan=3|(6,7)+| rowspan=3||-| β−, n (3.44%)| 97Zr|-| IT?| 98Y|-id=Yttrium-98m3| style="text-indent:1em" | 98m3Y| colspan="3" style="text-indent:2em" | 496.10(11) keV| 6.90(54) μs| IT| 98Y| (4)−||-id=Yttrium-98m4| style="text-indent:1em" | 98m4Y| colspan="3" style="text-indent:2em" | 594(10) keV| 180(7) ns| IT| 98Y| (3−,4−)||-id=Yttrium-98m5| style="text-indent:1em" | 98m5Y| colspan="3" style="text-indent:2em" | 972.17(20) keV| 450(150) ns| IT| 98Y| (8+)||-id=Yttrium-98m6| style="text-indent:1em" | 98m6Y| colspan="3" style="text-indent:2em" | 1181.50(18) keV| 762(14) ns| IT| 98Y| (10−)||-id=Yttrium-99| rowspan=2|99Y| rowspan=2 style="text-align:right" | 39| rowspan=2 style="text-align:right" | 60| rowspan=2|98.9241608(71)| rowspan=2|1.484(7) s| β− (98.23%)| 99Zr| rowspan=2|5/2+| rowspan=2||-| β−, n (1.77%)| 98Zr|-id=Yttrium-99m| style="text-indent:1em" | 99mY| colspan="3" style="text-indent:2em" | 2141.65(19) keV| 8.2(4) μs| IT| 99Y| (17/2+)||-id=Yttrium-100| rowspan=2|100Y| rowspan=2 style="text-align:right" | 39| rowspan=2 style="text-align:right" | 61| rowspan=2|99.927728(12)| rowspan=2|940(30) ms| β−| 100Zr| rowspan=2|4+| rowspan=2||-| β−, n?| 99Zr|-id=Yttrium-100m| rowspan=2 style="text-indent:1em" | 100mY| rowspan=2 colspan="3" style="text-indent:2em" | 144(16) keV| rowspan=2|727(6) ms| β− (98.92%)| 100Zr| rowspan=2|1+#| rowspan=2||-| β−, n (1.08%)| 99Zr|-id=Yttrium-101| rowspan=2|101Y| rowspan=2 style="text-align:right" | 39| rowspan=2 style="text-align:right" | 62| rowspan=2|100.9301608(76)| rowspan=2|426(20) ms| β− (97.7%)| 101Zr| rowspan=2|5/2+| rowspan=2||-| β−, n (2.3%)| 100Zr|-id=Yttrium-101m| style="text-indent:1em" | 101mY| colspan="3" style="text-indent:2em" | 1205.0(10) keV| 870(90) ns| IT| 101Y| 13/2−#||-id=Yttrium-102| rowspan=2|102Y| rowspan=2 style="text-align:right" | 39| rowspan=2 style="text-align:right" | 63| rowspan=2|101.9343285(44)| rowspan=2|360(40) ms| β− (>97.4%)| 102Zr| rowspan=2|(5−)| rowspan=2||-| β−, n (<2.6%)| 101Zr|-id=Yttrium-102m| rowspan=3 style="text-indent:1em" | 102mY[1] | rowspan=3 colspan="3" style="text-indent:2em" | 100(100)# keV| rowspan=3|300(100) ms| β− (>97.4%)| 102Zr| rowspan=3|(0−,1−)| rowspan=3||-| β−, n (<2.6%)| 101Zr|-| IT?| 102Y|-id=Yttrium-103| rowspan=2|103Y| rowspan=2 style="text-align:right" | 39| rowspan=2 style="text-align:right" | 64| rowspan=2|102.937244(12)| rowspan=2|239(12) ms| β− (92.0%)| 103Zr| rowspan=2|5/2+#| rowspan=2||-| β−, n (8.0%)| 102Zr|-id=Yttrium-104| rowspan=3|104Y| rowspan=3 style="text-align:right" | 39| rowspan=3 style="text-align:right" | 65| rowspan=3|103.94194(22)#| rowspan=3|197(4) ms| β− (66%)| 104Zr| rowspan=3|(0+,1+)#| rowspan=3||-| β−, n (34%)| 103Zr|-| β−, 2n?| 102Zr|-id=Yttrium-105| rowspan=3|105Y| rowspan=3 style="text-align:right" | 39| rowspan=3 style="text-align:right" | 66| rowspan=3|104.94571(43)#| rowspan=3|95(9) ms| β−| 105Zr| rowspan=3|5/2+#| rowspan=3||-| β−, n (<82%)| 104Zr|-| β−, 2n?| 103Zr|-id=Yttrium-106| rowspan=3|106Y| rowspan=3 style="text-align:right" | 39| rowspan=3 style="text-align:right" | 67| rowspan=3|105.95084(54)#| rowspan=3|75(6) ms| β−| 106Zr| rowspan=3|2+#| rowspan=3||-| β−, n?| 105Zr|-| β−, 2n?| 104Zr|-id=Yttrium-107| rowspan=3|107Y| rowspan=3 style="text-align:right" | 39| rowspan=3 style="text-align:right" | 68| rowspan=3|106.95494(54)#| rowspan=3|33.5(3) ms| β−| 107Zr| rowspan=3|5/2+#| rowspan=3||-| β−, n?| 106Zr|-| β−, 2n?| 105Zr|-id=Yttrium-108| rowspan=3|108Y| rowspan=3 style="text-align:right" | 39| rowspan=3 style="text-align:right" | 69| rowspan=3|107.96052(64)#| rowspan=3|30(5) ms| β−| 108Zr| rowspan=3|6−#| rowspan=3||-| β−, n?| 107Zr|-| β−, 2n?| 106Zr|-id=Yttrium-109| rowspan=3|109Y| rowspan=3 style="text-align:right" | 39| rowspan=3 style="text-align:right" | 70| rowspan=3|108.96513(75)#| rowspan=3|25(5) ms| β−| 109Zr| rowspan=3|5/2+#| rowspan=3||-| β−, n?| 108Zr|-| β−, 2n?| 107Zr|-id=Yttrium-110| 110Y[3] | style="text-align:right" | 39| style="text-align:right" | 71| ||||||-id=Yttrium-111| 111Y| style="text-align:right" | 39| style="text-align:right" | 72| | ||||