What is meant by half-life in the context of radioactive substances?

Half-life is defined as the time required for half of a radioactive substance to decay. This concept is fundamental in understanding radioactive decay processes and the behavior of unstable isotopes over time. When a radioactive material decays, it emits radiation and transforms into a different element or a more stable isotope. The half-life represents a specific interval during which exactly half of the original sample will have decayed, illustrating the predictable and exponential nature of radioactive decay.

For example, if you start with 100 grams of a radioactive substance with a half-life of 10 years, after 10 years, you would have 50 grams remaining. After another 10 years (20 years total), you would have 25 grams left, demonstrating how the amount of substance decreases by half in each successive half-life period.

This concept is crucial not only in chemistry and physics but also in fields such as archaeology (as in carbon dating) and medicine (such as understanding the decay of radioactive tracers in imaging and treatment). The accuracy of determining the half-life helps in predicting how long a radioactive substance will remain hazardous or useful in various applications.