Half-life

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

1. The half-life of a radioactive isotope is constant and does not depend on the initial amount or external conditions.
2. 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.
3. Commonly used isotopes with known half-lives include Carbon-14 (5730 years) and Uranium-238 (4.5 billion years).
4. Half-life can be used in radiometric dating to determine the age of archaeological finds.
5. A shorter half-life means quicker decay, while a longer half-life indicates slower decay.

Review Questions

• What is the definition of half-life in nuclear chemistry?
• How does the initial amount of a radioactive substance affect its half-life?
• Provide an example of how half-life is used in real-world applications.

Related terms

Radioactive Decay:

The process by which an unstable atomic nucleus loses energy by emitting radiation.

Isotope:

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.