What are isotopes that decay to more stable forms called?

Isotopes that decay to more stable forms are referred to as radioisotopes. This is because they are unstable or radioactive forms of an element that undergoes nuclear decay. During this decay process, they emit radiation and transform into more stable isotopes or elements. The term "radioisotope" specifically emphasizes the presence of this radioactivity and the transformation process involved, which can include alpha decay, beta decay, or gamma decay, eventually leading to a more stable configuration.

In contrast, stable isotopes do not undergo such decay processes and do not emit radiation. Stable atoms refer to the entirety of atoms that maintain their stability without any changes, whereas electrons are subatomic particles that do not directly pertain to the decay process of isotopes. Thus, the focus on stability and nuclear decay characteristics defines radioisotopes as the correct answer.