Why do radioactive nuclei emit alpha and beta particles?

[lonewolf219]

Hi, just learning about alpha and beta particles in class this week. What does it mean that the nucleus is unstable in a radioactive isotope? Is this a condition that must be present for nuclear radiation?

 

[mathman]

A radioactive isotope (by definition) is one that is unstable. This almost always involves alpha or beta (+ or -) particle output. There is a rare reaction, electron capture, where no particle is emitted.