Uranium-238

Uranium-238 is the most abundant naturally occurring uranium isotope, containing 92 protons and 146 neutrons. It decays chiefly through a long radioactive series and has a half-life of about 4.47 billion years.

Uranium series: A radioactive decay chain beginning with uranium-238 and ending at stable lead-206. This is the principal sequence by which uranium-238 decays.
Uranium–lead dating: A radiometric dating method that uses uranium isotopes decaying into lead isotopes. The uranium-238-to-lead-206 system dates ancient rocks and minerals.
Isotope: One of two or more atoms of the same element with different numbers of neutrons. Uranium-238 is one isotope among several nuclei with 92 protons.
R-process: A nucleosynthesis process that builds heavy atomic nuclei through rapid neutron capture. Uranium-238 is produced through neutron-rich events involving rapid neutron capture.
Radiogenic heat: Heat generated inside a planet by radioactive decay of unstable isotopes. Uranium-238 decay contributes to Earth's internal heat over geological time.
Alpha decay: Radioactive decay in which a nucleus emits a helium-4 nucleus. Uranium-238 begins its decay chain by emitting an alpha particle.
Depleted uranium: Uranium from which much of the uranium-235 has been removed, leaving mostly uranium-238. It is the principal material left after uranium enrichment.
Uranium: A radioactive chemical element with atomic number 92. Uranium-238 is the element's most abundant isotope.
Supernova nucleosynthesis: The creation of new nuclei in the explosions of massive stars. Supernovae were once proposed as a major source of heavy elements such as uranium.
Geochronology: The science of determining the age and sequence of geological events. Its long-lived decay system anchors dates for Earth's oldest rocks.

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