Interactive visualization of the three natural radioactive decay series — every alpha and beta step from parent to stable end product.
Nature has three naturally occurring decay chains, each named after the longest-lived isotope in the series. The Uranium-238 series (also called the Radium series) ends at Lead-206 after 14 steps. The Thorium-232 series ends at Lead-208 after 12 steps. The Uranium-235 series (Actinium series) ends at Lead-207 after 11 steps. In each chain, the parent isotope undergoes a sequence of alpha and beta decays until it reaches a stable lead isotope.
A fourth series — the Neptunium-237 series — exists but is not naturally occurring because Np-237 has a half-life of only 2.14 million years, far too short to have survived since the formation of the solar system. All members of this chain have long since decayed away on Earth.