| atomic number | a radioactive element of the actinide series |
|---|---|
| atomic number | a nonmetallic univalent element belonging to the halogens |
| atomic number | a soft silvery-white tetravalent radioactive metallic element |
| atomic number | a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead |
| atomic number | a heavy toxic silvery-white radioactive metallic element |
| atomic number | a radioactive transuranic metallic element |
| atomic number | a radioactive transuranic element that is similar to uranium |
| atomic number | a radioactive transuranic metallic element |
| atomic number | a radioactive transuranic metallic element |
| atomic number | a radioactive transuranic element |
| atomic number | a radioactive transuranic element |
| atomic number | a radioactive transuranic element produced by bombarding plutonium with neutrons |