polonium218

Polonium-218 (Po-218) is a radioactive isotope of polonium with a mass number of 218 and atomic number 84. It is part of the uranium-238 decay chain, arising from the alpha decay of radon-222 and decaying to lead-214 in turn. Po-218 has a short half-life of about 3.05 minutes and decays by alpha emission, releasing an energetic alpha particle.

In natural settings, Po-218 appears briefly within uranium-bearing materials as radon-222 decays. Its rapid decay means it exists only in trace amounts and is continually replenished from radon decay. It is one of several short-lived intermediates in the uranium-238 series.

From a safety perspective, Po-218 emits alpha radiation. External exposure is relatively easily shielded, but inhalation or ingestion can deliver significant internal doses due to localization in the lungs and other tissues. Consequently, handling Po-218 requires strict radiological controls. It is not used commercially, because of its short half-life and high radiotoxicity; research uses typically involve other isotopes or sealed sources.

Chemically, polonium behaves similarly to other chalcogens, but radioactivity is the dominant feature governing its behavior in most contexts. Po-218 is a transient member of the uranium-238 decay chain and, due to its brief existence, is primarily of interest in studies of radioactive decay sequences and radon progeny.