What is the term for the time it takes for half of a radioactive substance to decay?

The term that describes the time required for half of a radioactive substance to decay is known as half-life. This concept is crucial in understanding radioactive decay, as it provides a measure of the rate at which a particular isotope undergoes transformation into a different state, typically another element or a different isotope.

Half-life is a fixed characteristic of each radioactive isotope, indicating that no matter how much of the substance is present, the time it takes for half of it to decay remains constant. This property allows scientists and professionals to predict how long it will take for a substance to lose half of its radioactivity, which is essential for radiation safety, medical applications such as radiotherapy, and environmental assessments.

Other terms like decay constant represent the probability of decay per unit time, while radiation exposure time pertains to the amount of time a person is exposed to radiation and emission rate deals with the rate at which radiation is emitted from a source. These concepts are related but distinct from the specific measurement of half-life. Understanding this distinction is key for effectively applying knowledge of radiological safety and assessment.