Radioactive Decay
When nuclei fall outside the Band of Stability, they undergo radioactive decay to reach stability. Think of it as nature's way of fixing unstable atoms! These decay processes change the neutron-to-proton ratio by adjusting the number of protons, neutrons, or both.
There are three main types of radioactive decay you need to know. Alpha decay occurs when a nucleus emits an alpha particle—essentially a helium nucleus with 2 protons and 2 neutrons. Alpha particles have a positive charge and can be stopped by something as thin as paper!
Beta decay happens when an unstable neutron converts into a proton and emits an electron (the beta particle). These negatively charged particles can penetrate paper but are stopped by aluminum. Meanwhile, gamma decay produces high-energy photons that have no mass or charge and often accompanies other decay types.
Each decay type has different penetrating abilities. Alpha particles are stopped by paper, beta particles by aluminum, and gamma rays sometimes require lead shielding to be blocked completely.
Important! When studying radioactive decay, remember that each decay type changes the atom in specific ways: alpha decay decreases both mass number and atomic number, while beta decay increases the atomic number but keeps the mass number the same.