Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Half-life is the time required for half of the radioactive nuclei in a sample to decay. It is a characteristic property of each radioactive isotope.
5 Must Know Facts For Your Next Test
The half-life of a radioactive isotope is constant and does not depend on the initial amount or external conditions.
The formula to calculate the remaining quantity of a substance after n half-lives is $N = N_0 \times (\frac{1}{2})^n$ where $N_0$ is the initial quantity.
Commonly used isotopes with known half-lives include Carbon-14 (5730 years) and Uranium-238 (4.5 billion years).
Half-life can be used in radiometric dating to determine the age of archaeological finds.
A shorter half-life means quicker decay, while a longer half-life indicates slower decay.
Variants of a particular chemical element that have different neutron numbers but the same number of protons.
Radiometric Dating: A method used to date materials such as rocks or carbon, based on comparing the relative proportions of specific radioactive isotopes present.