thorium231

Thorium-231, often written as 231Th, is a radioactive isotope of thorium with mass number 231 and atomic number 90. It is part of the actinide series. In nature it is not present in appreciable amounts; it is produced temporarily in the decay chains of heavier nuclides such as uranium-235 and through controlled neutron irradiation in reactors or laboratory experiments.

Decay and half-life: 231Th undergoes beta decay to protactinium-231, with a half-life on the order of a few days. The decay product, Pa-231, continues the decay chain toward heavier elements and ultimately to stable lead.

Chemical properties: As a thorium isotope, 231Th shares chemical behavior with thorium, typically existing in the tetravalent state in compounds. It forms the same types of fluorides, oxides, and complex ions as other thorium isotopes.

Applications and safety: 231Th is mainly of interest for nuclear science research, including studies of decay schemes and radiochemical tracing. Its short half-life means it is not used as a long-term radiotracer or in industrial applications. Handling requires appropriate radiation safety measures and containment to limit exposure.

See also: Thorium series, Protactinium-231.