The stability of an atom depends on the balance between the number of protons and neutrons in its nucleus. The specific number of protons and neutrons required for stability varies depending on the element or isotope in question.
In general, for lighter elements, the number of neutrons and protons in stable nuclei is roughly equal. This balance helps to minimize the electrostatic repulsion between the positively charged protons, which stabilizes the nucleus. As elements become heavier, the number of neutrons needed to maintain stability relative to protons tends to increase.
However, it's important to note that stability is not solely determined by the number of protons and neutrons but also by the specific nuclear forces and other factors at play within the nucleus.
If an atom has an excess of neutrons or protons beyond what is considered stable, it becomes an unstable or radioactive isotope. Unstable isotopes undergo radioactive decay, during which they spontaneously release particles and/or energy in order to achieve a more stable configuration. This decay process can involve the emission of alpha particles (helium nuclei), beta particles (electrons or positrons), or gamma rays (high-energy photons), among other possibilities.
The stability of an atom is a delicate balance, and the specific ratios of protons and neutrons required for stability can vary widely depending on the element and isotope. Nuclei with too many or too few nucleons relative to the stable configuration will typically undergo radioactive decay to reach a more stable state.