釷的同位素
圖表

| 符號 | 歷史 名稱 | Z> 激發能量 | N> 激發能量 | 同位素質量（u） > 激發能量 | 半衰期 | 衰變方式 | 衰變產物 | 原子核 自旋 | 相對豐度 （莫耳分率） | 相對豐度 的變化量 （莫耳分率） |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 207Th |  | 90 | 117 |  | 9.7(+46.6−4.4) ms | α | 203Ra |  |  |  |
| 208Th |  | 90 | 118 | 208.01791(4) | 1.7(+1.7-0.6) ms | α | 204Ra | 0+ |  |  |
| 209Th |  | 90 | 119 | 209.01772(11) | 7(5) ms [3.8(+69−15)] | α | 205Ra | 5/2−# |  |  |
| 210Th |  | 90 | 120 | 210.015075(27) | 17(11) ms [9(+17−4) ms] | α | 206Ra | 0+ |  |  |
| 210Th |  | 90 | 120 | 210.015075(27) | 17(11) ms [9(+17−4) ms] | β+ （不常見） | 210Ac | 0+ |  |  |
| 211Th |  | 90 | 121 | 211.01493(8) | 48(20) ms [0.04(+3−1) s] | α | 207Ra | 5/2−# |  |  |
| 211Th |  | 90 | 121 | 211.01493(8) | 48(20) ms [0.04(+3−1) s] | β+ （不常見） | 211Ac | 5/2−# |  |  |
| 212Th |  | 90 | 122 | 212.01298(2) | 36(15) ms [30(+20-10) ms] | α (99.7%) | 208Ra | 0+ |  |  |
| 212Th |  | 90 | 122 | 212.01298(2) | 36(15) ms [30(+20-10) ms] | β+ (.3%) | 212Ac | 0+ |  |  |
| 213Th |  | 90 | 123 | 213.01301(8) | 140(25) ms | α | 209Ra | 5/2−# |  |  |
| 213Th |  | 90 | 123 | 213.01301(8) | 140(25) ms | β+ （不常見） | 213Ac | 5/2−# |  |  |
| 214Th |  | 90 | 124 | 214.011500(18) | 100(25) ms | α | 210Ra | 0+ |  |  |
| 215Th |  | 90 | 125 | 215.011730(29) | 1.2(2) s | α | 211Ra | (1/2−) |  |  |
| 216Th |  | 90 | 126 | 216.011062(14) | 26.8(3) ms | α (99.99%) | 212Ra | 0+ |  |  |
| 216Th |  | 90 | 126 | 216.011062(14) | 26.8(3) ms | β+ (.006%) | 216Ac | 0+ |  |  |
| 216m1Th |  | 2042(13) keV | 2042(13) keV | 2042(13) keV | 137(4) µs |  |  | (8+) |  |  |
| 216m2Th |  | 2637(20) keV | 2637(20) keV | 2637(20) keV | 615(55) ns |  |  | (11−) |  |  |
| 217Th |  | 90 | 127 | 217.013114(22) | 240(5) µs | α | 213Ra | (9/2+) |  |  |
| 218Th |  | 90 | 128 | 218.013284(14) | 109(13) ns | α | 214Ra | 0+ |  |  |
| 219Th |  | 90 | 129 | 219.01554(5) | 1.05(3) µs | α | 215Ra | 9/2+# |  |  |
| 219Th |  | 90 | 129 | 219.01554(5) | 1.05(3) µs | β+ (10−7%) | 219Ac | 9/2+# |  |  |
| 220Th |  | 90 | 130 | 220.015748(24) | 9.7(6) µs | α | 216Ra | 0+ |  |  |
| 220Th |  | 90 | 130 | 220.015748(24) | 9.7(6) µs | ε (2×10−7%) | 220Ac | 0+ |  |  |
| 221Th |  | 90 | 131 | 221.018184(10) | 1.73(3) ms | α | 217Ra | (7/2+) |  |  |
| 222Th |  | 90 | 132 | 222.018468(13) | 2.237(13) ms | α | 218Ra | 0+ |  |  |
| 222Th |  | 90 | 132 | 222.018468(13) | 2.237(13) ms | ε (1.3×10−8%) | 222Ac | 0+ |  |  |
| 223Th |  | 90 | 133 | 223.020811(10) | 0.60(2) s | α | 219Ra | (5/2)+ |  |  |
| 224Th |  | 90 | 134 | 224.021467(12) | 1.05(2) s | α | 220Ra | 0+ |  |  |
| 225Th |  | 90 | 135 | 225.023951(5) | 8.72(4) min | α (90%) | 221Ra | (3/2)+ |  |  |
| 225Th |  | 90 | 135 | 225.023951(5) | 8.72(4) min | ε (10%) | 225Ac | (3/2)+ |  |  |
| 226Th |  | 90 | 136 | 226.024903(5) | 30.57(10) min | α | 222Ra | 0+ |  |  |
| 227Th | Radioactinium | 90 | 137 | 227.0277041(27) | 18.68(9) d | α | 223Ra | 1/2+ | Trace |  |
| 228Th | Radiothorium | 90 | 138 | 228.0287411(24) | 1.9116(16) y | α | 224Ra | 0+ | Trace |  |
| 228Th | Radiothorium | 90 | 138 | 228.0287411(24) | 1.9116(16) y | CD (1.3×10−11%) | 208Pb 20O | 0+ | Trace |  |
| 229Th |  | 90 | 139 | 229.031762(3) | 7.34(16)×103 y | α | 225Ra | 5/2+ |  |  |
| 229mTh |  | 8.3(2) eV | 8.3(2) eV | 8.3(2) eV | 7(1) μs | IT | 229Th | 3/2+ |  |  |
| 230Th | Ionium | 90 | 140 | 230.0331338(19) | 7.538(30)×104 y | α | 226Ra | 0+ | Trace  |  |
| 230Th | Ionium | 90 | 140 | 230.0331338(19) | 7.538(30)×104 y | CD (5.6×10−11%) | 206Hg 24Ne | 0+ | Trace  |  |
| 230Th | Ionium | 90 | 140 | 230.0331338(19) | 7.538(30)×104 y | SF (5×10−11%) | (Various) | 0+ | Trace  |  |
| 231Th | Uranium Y | 90 | 141 | 231.0363043(19) | 25.52(1) h | β− | 231Pa | 5/2+ | Trace |  |
| 231Th | Uranium Y | 90 | 141 | 231.0363043(19) | 25.52(1) h | α (10−8%) | 227Ra | 5/2+ | Trace |  |
| 232Th | Thorium | 90 | 142 | 232.0380553(21) | 1.405(6)×1010 y | α | 228Ra | 0+ | 1.0000 |  |
| 232Th | Thorium | 90 | 142 | 232.0380553(21) | 1.405(6)×1010 y | SF (1.1×10−9%) | (various) | 0+ | 1.0000 |  |
| 232Th | Thorium | 90 | 142 | 232.0380553(21) | 1.405(6)×1010 y | CD (2.78×10−10%) | 182Yb 26Ne 24Ne | 0+ | 1.0000 |  |
| 233Th |  | 90 | 143 | 233.0415818(21) | 21.83(4) min | β− | 233Pa | 1/2+ |  |  |
| 234Th | Uranium X1 | 90 | 144 | 234.043601(4) | 24.10(3) d | β− | 234mPa | 0+ | Trace |  |
| 235Th |  | 90 | 145 | 235.04751(5) | 7.2(1) min | β− | 235Pa | (1/2+)# |  |  |
| 236Th |  | 90 | 146 | 236.04987(21)# | 37.5(2) min | β− | 236Pa | 0+ |  |  |
| 237Th |  | 90 | 147 | 237.05389(39)# | 4.8(5) min | β− | 237Pa | 5/2+# |  |  |
| 238Th |  | 90 | 148 | 238.0565(3)# | 9.4(20) min | β− | 238Pa | 0+ |  |  |
1 2  畫上#號的數據代表沒有經過實驗的証明，僅為理論推測。
1 2 3 4  用括號括起來的數據代表不確定性。
↑  半衰期超过5亿年的同位素以粗體表示。
↑  穩定的衰變產物以粗體表示。
1 2  位於235U衰變鏈
↑  位於232Th衰變鏈
↑  用在鈾釷定年（英语：）
1 2  位於238U的衰變鏈
↑  原始（英语：）放射性核素
| 0 | 1 | 2 |
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