Radioactivity
Radioactivity explained in an easy to understand way:
Imagine you're trying to balance a stack of books that keeps wobbling because it's not stable. Just like the stack of books, an unstable atomic nucleus is also in a precarious state and seeks stability. In both cases, the wobbly stack will eventually topple over or require you to remove some books to stabilize it, just as the unstable nucleus achieves stability by emitting radiation in the form of particles or energy, thereby altering its structure.
Practice Version
Radioactivity: The ability of an unstable nucleus to emit radiation. Radioactivity. It is the process where unstable atoms release energy in the form of particles or rays to become stable.