What are the types of radiation emitted by the nuclei of radioactive elements?

Alpha particles, Beta particles, gamma rays, and neutrons

Explanation:

usually there's 2 ways radioactivity occurs: radioactive decay and ionization. radioactive decay breaks down the nucleas over time transforming the protons and neutrons into smaller particles alpha and beta with a little gamma radiation (gamma radiation is what was decaying). ionization is when the nucleas ejects neutrons as it's form of decay, leaving radioactive isotopes.