Take me to A Reporter's Guide. .
Atoms release radiation as they change from unstable, energized forms to more stable forms.
Stable isotopes do not undergo radioactive decay and therefore do not emit radiation. Types of Radiation Radiation is either ionizing or nonionizing. They are easily shielded by a sheet of paper or the outer layer of a person's skin. Beta particles , which are identical to electrons, are more energetic than alpha particles. They can travel in the air for a distance of a few feet.