When a unstable radioactive atom degrades what happens to it?

Answer 1

You probably mean decays, not degrades. When an unstable atom decays it goes through one of the following processes:

• Alpha decay - a helium nucleus is ejected reducing the element number by 2 and the mass number by 4.
• Beta decay - a neutron decays to a proton, electron, and a neutrino. The electron and neutrino are ejected increasing the element number by 1 and leaving the mass number constant.
• Gamma decay - the protons and neutrons in the nucleus rearrange themselves into a lower energy state and a gamma ray photon is ejected to remove the excess energy. Neither the element or mass numbers change.
• Fission - certain transient metastable isotopes (e.g. U236 produced by U235 capturing a neutron) can split into two smaller nuclei and eject 2 or more neutrons. Note: Fission is not usually considered a decay process.

Answer 2

When an unstable radioactive atom decays, it releases energy in the form of radiation in order to become more stable. This decay process can result in the emission of alpha or beta particles, gamma rays, or the formation of a new element altogether.