From dating artifacts using carbon-14 to tracing abnormalities in the thyroid using iodine-131, we as humans have made many advances in various fields through the use of radioactive isotopes, or radioactive forms of specific elements with a specific number of neutrons. In many of these applications, a quantity known as half-life is utilized, which refers to the amount of time needed for an original sample to decay to one half of its initial value.

Half-life can be used to calculate fractions and remaining masses of an original sample that will remain after a certain amount of time. Understanding how to calculate and use half-life when determining how much of a radioisotope remains after time is the key to advancing knowledge in various fields, including the age of fossils and the effectiveness of medicinal drugs over time.

First, try the practice questions to determine what you already know about half-life. Then, watch the video lesson to learn more about half-life.