Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
A radioactive isotope, also known as a radioisotope, is an atom that has excess nuclear energy, making it unstable. This instability leads to the atom releasing radiation until it becomes more stable.
Related terms
Half: life - The time required for half of the radioactive atoms in a sample to decay into more stable forms.