How many elements are radioactive?
Quick Answer
About 38 elements have no stable isotopes and are considered radioactive in all their forms. Several additional elements also have radioactive isotopes even if some stable ones exist.
The Full Story
Roughly 38 elements have no stable isotopes at all, which means every atom of those elements is radioactive. These include technetium, promethium, and all elements from polonium onward in the periodic table. In addition, many elements with stable isotopes also have radioactive isotopes. Radioactivity arises when nuclei are unstable and decay into more stable forms by emitting particles or energy. The boundary between stable and radioactive elements is therefore important in nuclear chemistry, medicine, and geology.
Key Facts
YouTube Angle
Suggested video title for this topic:
"How many elements are radioactive from the start?"
Was this answer helpful?
Tap a reaction — it helps us pick what to cover next.