Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
A radioactive decay series is a sequence of radioactive decays that proceed until a stable, non-radioactive isotope is formed. Each step in the series involves the transformation of one element into another through alpha or beta decay.
5 Must Know Facts For Your Next Test
A radioactive decay series starts with a parent isotope and ends with a stable daughter isotope.
There are three naturally occurring radioactive decay series: uranium-238, thorium-232, and uranium-235.
Alpha decays decrease the atomic number by 2 and mass number by 4, while beta decays increase the atomic number by 1 without changing the mass number.
The uranium-238 series eventually leads to lead-206 through multiple alpha and beta decays.
Decay series are important for understanding radiometric dating and the age of geological formations.
A type of radioactive decay where an atomic nucleus emits an alpha particle (2 protons and 2 neutrons), decreasing its atomic number by 2 and mass number by 4.
A type of radioactive decay where a neutron transforms into a proton, emitting an electron (beta particle) and an antineutrino, increasing the atomic number by 1.
Half-Life: The time required for half of the atoms in a sample of a radioactive substance to undergo decay.