What term describes the time it takes for a radioactive material to decay to half its activity?

The term that describes the time it takes for a radioactive material to decay to half its activity is known as "half-life." This is a fundamental concept in nuclear physics and radiochemistry, representing the duration required for half of the radioactive atoms in a sample to undergo decay. It is a critical factor in understanding the stability and behavior of radioactive substances over time.

Half-life is unique to each radioactive isotope, meaning that different materials will have significantly different half-lives. For example, Uranium-238 has a half-life of about 4.5 billion years, while Carbon-14 has a half-life of approximately 5,730 years. This concept is vital in various applications, including radiometric dating, nuclear medicine, and understanding radioactive waste management.

In contrast, the other terms listed— "half-death," "decay period," and "activity duration"—do not accurately describe this scientific phenomenon and are not commonly used in radiological contexts. Understanding the concept of half-life is essential for anyone working with radioactive materials or studying their effects.