In the context of radioactive decay and nuclear physics, half-life describes the time it takes for half of a quantity of a substance undergoing decay to go through transformation. In simpler terms, half-life is the duration it takes for a radioactive substance to lose half of its initial radioactivity.
For example, if you start with a certain amount of a radioactive substance, after one half-life, half of that substance will have decayed, and you will have half of the original amount. After two half-lives, three-quarters will have decayed, and so on.
Radioactive Decay and Isotopes
Half-life is a characteristic property of each radioactive isotope, and it plays a crucial role in understanding the stability and decay of atomic nuclei. You can express the concept mathematically through an exponential decay model, where the rate of decay is proportional to the remaining quantity of the substance.
The half-life of a radioactive isotope — denoted by T1/2 — varies widely depending on the specific isotope. Each has its own unique half-life. Some isotopes have very short half-lives, measured in seconds or minutes, while others have half-lives that extend over thousands or millions of years.
The concept of half-life is not limited to radioactive decay; other fields like medicine, chemistry and environmental science also measure half-life.