| Proton | Neutron | Nuclear Spin | Energy State | |
|---|---|---|---|---|
| 241Fm | 100 | 141 | 5/2 | |
| 242Fm | 100 | 142 | 0 | |
| 243Fm | 100 | 143 | -7/2 | |
| 244Fm | 100 | 144 | 0 | |
| 245Fm | 100 | 145 | 1/2 | |
| 246Fm | 100 | 146 | 0 | |
| 247Fm | 100 | 147 | 7/2 | |
| 248Fm | 100 | 148 | 0 | |
| 249Fm | 100 | 149 | 7/2 | |
| 250Fm | 100 | 150 | 0 | |
| 251mFm | 100 | 151 | 5/2 | |
| 251Fm | 100 | 151 | -9/2 | |
| 252Fm | 100 | 152 | 0 | |
| 253Fm | 100 | 153 | 1/2 | |
| 254Fm | 100 | 154 | 0 | |
| 255Fm | 100 | 155 | 7/2 | |
| 256Fm | 100 | 156 | 0 | |
| 257Fm | 100 | 157 | 9/2 | |
| 258Fm | 100 | 158 | 0 | |
| 259Fm | 100 | 159 | 3/2 | |
| 260Fm | 100 | 160 | 0 |