Daughter Isotope Definition - Chemistry Glossary

What Is a Daughter Isotope?

Alpha decay schematic
In alpha decay, a parent nucleus decays into a daughter nucleus and an alpha particle.

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by Anne Marie Helmenstine, Ph.D.
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
Updated January 12, 2020

A daughter isotope is the product which remains after an original isotope has undergone radioactive decay. The original isotope is termed the parent isotope. A daughter isotope is also known as a daughter product, daughter nuclide, decay product, or radio-daughter.

Example

For example, uranium-238 decays along what is called a decay chain:

238U → 234Th → 234mPa → ... → 206Pb

Uranium-238 is the parent isotope, while thorium-234, protactinium-234m, and lead-206 are all daughter isotopes.

Daughter Isotopes and Half-Life

The half-life of an isotope is used to predict the time half of a sample will decay into a daughter isotope, but it cannot predict when an individual atom will decay into a daughter product. However, the nature of the decay product(s) form is highly predictable.

Sources

  • Peh, W. C. G. (1996). "The Discovery of Radioactivity and Radium." Singapore Medical Journal. 37 (6): 627–630.