What is radioactive decay?

Chemistry and Math Read more from
Chapter Math in the Physical Sciences

Mathematics can also be applied to radioactive substances found within certain rocks. Radioactive decay is the disintegration of a radioactive substance and the emission of certain ionizing radiation (such as alpha or beta particles—or even gamma rays). Simply put, when rocks form, the minerals within the rock often contain certain radioactive atoms that decay at a specific rate.

Radioactive decay is especially important in radioactive dating, in which the original and decayed radioactive elements are used to determine the age of the rock. This is because certain radioactive elements will decay to a mixture of half the original element and half another element (or isotope) in a specific timeframe; this is also called the half-life of the original element. For example, “half” of the Uranium-238 in a rock will decay into Lead-207 in 704 million years (thus, the half-life of Uranium-238 is said to be 704 million years). Statistically, this change follows a specific decay function for each isotope of an element. And in each of these exponential functions, the time for the function’s value to decrease to half is constant, making radioactive dating perfect in determining the age of certain rocks.


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