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nouna radioactive element of the actinide series; found in uranium ores
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Definition that contains actinium
- pa a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead
- fr a radioactive element of the alkali-metal group discovered as a disintegration product of actinium
- francium a radioactive element of the alkali-metal group discovered as a disintegration product of actinium
- atomic number 87 a radioactive element of the alkali-metal group discovered as a disintegration product of actinium
- atomic number 91 a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead
- protactinium a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead
- actinide series (chemistry) a series of 15 radioactive elements with increasing atomic numbers from actinium to lawrencium
- protoactinium a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead