Protactinium

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Periodensystem Mendelejews

Decay chain(4n+2, Uranium series)

Uraninite-39029

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PaCl5

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Uranocene-3D-balls

Protactinium is a chemical element with the symbol Pa and atomic number 91. It is a dense, silvery-gray metal which readily reacts with oxygen, water vapor, and inorganic acids. Protactinium is part of the actinide series, which is located in the f-block of the periodic table of elements. It is one of the less common naturally occurring elements and is considered highly radioactive and toxic.

Properties

Protactinium has a bright metallic luster that it retains for some time in air. Its physical and chemical properties are intermediate between those of thorium and uranium. When it oxidizes, it forms a white oxide layer. Due to its high radioactivity, protactinium is considered a hazardous material, requiring special handling techniques and storage protocols.

Isotopes

The most common isotopes of protactinium are ^231Pa and ^233Pa. ^231Pa has a half-life of about 32,760 years and decays to actinium-227 through alpha decay. ^233Pa is a product of the neutron irradiation of ^232Th and decays into ^233U, which is of interest in nuclear reactors and nuclear weapons design due to its potential for use as a nuclear fuel.

History

Protactinium was first identified in 1913 by Kasimir Fajans and O.H. Göhring and was named "brevisium" (from Latin brevis, meaning short) due to the short half-life of the isotope they discovered, ^234Pa. The element was independently discovered by Frederick Soddy and John Cranston in 1918. The name "protactinium" was proposed in 1918, which means "parent of actinium," reflecting its position in the decay chain of uranium-235 to actinium.

Occurrence

Protactinium is found in minute quantities in the Earth's crust, within uranium ores. The most significant source of protactinium is the decay of uranium-235 in nuclear reactors. It is extracted from spent nuclear fuel in a complex process that involves several chemical separation stages due to its scarcity and the high radioactivity of the materials involved.

Applications

Due to its scarcity, high radioactivity, and toxicity, protactinium has limited applications. It has been used in research purposes and in the study of the behavior of actinides. Its isotope, ^231Pa, has potential use in dating marine sediments and ice cores in geochronology and paleoclimatology.

Safety

Handling protactinium requires stringent safety measures to protect against its radioactivity. It poses both an inhalation and ingestion hazard. Laboratories working with protactinium must employ containment systems, such as glove boxes, and follow strict protocols for its use, storage, and disposal.

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