Radioactivity

In summary, radioactivity is the process by which an unstable atom becomes stable by emitting a particle. Radioactive decay is a random process where the amount of the substance that is remaining decreases exponentially over time.  Half-life is the amount of time it takes for half of the amount of a substance to decay. There are three types of decay named after the first three letters of the Greek alphabet – alpha, beta, and gamma. An alpha particle is a Helium nucleus, a beta minus particle is an electron, a beta plus particle is a positron, and a gamma particle is a high energy photon. You should know how to write the decay reactions for each type of decay. For all types of decay, the number of nucleons is conserved and charge is conserved.