Np
Neptunium
Z 93 237.0 g/molActinide Radioactive
| 219Np | 126 | 219.0316 | 29,440.0 | --- | 570.0 µs | (9/2-) | α→215Pa(100%) | 2015 |
| 220Np | 127 | 220.0327 | 30,480.0 | --- | 29.0 ns | (1-) | α→216Pa(100%) | 2019 |
| 221Np | 128 | 221.0321 | 29,910.0 | --- | 30.0 ns | (9/2-) | α→217Pa | --- |
| 222Np | 129 | 222.0336 | 31,270.0 | --- | 480.0 ns | (1-) | α→218Pa(100%) | 2020 |
| 223Np | 130 | 223.0329 | 30,660.0 | --- | 2.5 µs | (9/2-) | α→219Pa(100%) | 2017 |
| 224Np | 131 | 224.0344 | 32,032.0 | --- | 48.0 µs | (2-) | α→220Pa(100%) | 2018 |
| 225Np | 132 | 225.0339 | 31,620.0 | --- | 6.5 ms | (9/2-) | α→221Pa(100%) β⁺→225U | 1994 |
| 226Np | 133 | 226.0352 | 32,820.0 | --- | 35.0 ms | --- | α→222Pa(100%) β⁺→226U | 1990 |
| 227Np | 134 | 227.035 | 32,580.0 | --- | 510.0 ms | (5/2+) | α→223Pa(100%) β⁺→227U | 1990 |
| 228Np | 135 | 228.0363 | 33,830.0 | --- | 1.02 m | (4+) | EC→228U(59%) α→224Pa(41%) β⁺SF(0.012%) | 1994 |
| 229Np | 136 | 229.0363 | 33,800.0 | --- | 4.0 m | (5/2+) | α→225Pa(68%) β⁺→229U | 1968 |
| 230Np | 137 | 230.0378 | 35,240.0 | --- | 4.6 m | (4+) | β⁺→230U(<97%) α→226Pa(>3%) | 1968 |
| 231Np | 138 | 231.0382 | 35,620.0 | --- | 48.8 m | (5/2+) | β⁺→231U(98%) α→227Pa(2%) | 1950 |
| 232Np | 139 | 232.0401 | 37,360.0 | --- | 14.7 m | (5-) | β⁺→232U(100%) α→228Pa | 1950 |
| 233Np | 140 | 233.0407 | 37,950.0 | --- | 36.2 m | (5/2+) | β⁺→233U(~100%) α→229Pa(0.001%) | 1950 |
| 234Np | 141 | 234.0429 | 39,955.0 | --- | 4.4 d | (0+) | β⁺→234U(100%) | 1949 |
| 235Np | 142 | 235.0441 | 41,043.0 | --- | 1.08 y | 5/2+ | EC→235U(99.997%) α→231Pa(0.003%) | 1949 |
| 236Np | 143 | 236.0466 | 43,380.0 | --- | 153.0 ky | (6-) | EC→236U(86.3%) β⁻→236Pu(13.5%) α→232Pa(0.16%) | 1949 |
| 236mNp | 143 | 236.0466 | 43,438.0 | --- | 22.5 h | (1-) | EC→236U(50%) β⁻→236Pu(50%) | 1949 |
| 237Np | 144 | 237.0482 | 44,871.6 | --- | 2.14 My | 5/2+ | α→233Pa(~100%) SF(<2e-10%) CD→207Tl(<4e-12%) | 1948 |
| 237mNp | 144 | 237.0492 | 45,816.8 | --- | 710.0 ns | 13/2- | γ→237Np(100%) | 1990 |
| 238Np | 145 | 238.0509 | 47,454.6 | --- | 2.1 d | 2+ | β⁻→238Pu(100%) | 1949 |
| 238mNp | 145 | 238.0534 | 49,760.0 | --- | 112.0 ns | --- | SF(100%) γ→238Np | 1970 |
| 239Np | 146 | 239.0529 | 49,311.0 | --- | 2.36 d | 5/2+ | β⁻→239Pu(100%) α→235Pa | 1940 |
| 240Np | 147 | 240.0562 | 52,316.0 | --- | 1.03 h | (5+) | β⁻→240Pu(100%) | 1953 |
| 240mNp | 147 | 240.0562 | 52,334.0 | --- | 7.22 m | (1+) | β⁻→240Pu(99.88%) γ→240Np(0.12%) | 1948 |
| 241Np | 148 | 241.0583 | 54,320.0 | --- | 13.9 m | (5/2+) | β⁻→241Pu(100%) α→237Pa | 1959 |
| 242Np | 149 | 242.0616 | 57,420.0 | --- | 2.2 m | (1+) | β⁻→242Pu(100%) | 1979 |
| 242mNp | 149 | 242.0617 | 57,470.0 | --- | 5.5 m | (6+) | β⁻→242Pu(100%) | 1981 |
| 243Np | 150 | 243.0642 | 59,810.0 | --- | 1.85 m | (5/2+) | β⁻→243Pu(100%) | 1979 |
| 244Np | 151 | 244.0679 | 63,240.0 | --- | 2.29 m | (7-) | β⁻→244Pu(100%) | 1987 |
| 245Np | 152 | 245.0707 | 65,850.0 | --- | 6.0 m | (5/2+) | β⁻→245Pu | --- |