Properties and Overview of Promethium

Overview:

Promethium (Pm) is a rare earth metal belonging to the lanthanide series of the periodic table, identified by the atomic number 61. It is one of the few elements not in nature in significant quantities, as all its isotopes are radioactive and decay relatively quickly. Consequently, promethium is primarily produced synthetically, typically as a byproduct in nuclear reactors during the fission of uranium-235 or from neutron bombardment of neodymium-146. Promethium is a soft, silvery metal that resembles other lanthanides in appearance. It exists in two allotropic forms and is typically reactive like other rare earth metals. However, due to its radioactivity, handling of bulk promethium metal is rare and usually encountered in compound form.
Promethium primarily forms compounds in the +3 oxidation state, common among lanthanides. These compounds are typically pale pink or red. The metal reacts with oxygen to form oxides and dissolves in acids to produce promethium salts. Its chemical behavior is similar to other lanthanides like neodymium and samarium, though the radioactivity of promethium can influence its reactivity and the stability of its compounds.
Given its radioactivity, promethium must be handled with care. The most stable isotope, promethium-145, emits beta radiation, which can pose health risks if ingested or inhaled. Proper shielding, containment, and protective gear are essential when working with promethium to prevent radiation exposure. Long-term exposure to promethium can increase the risk of cancer, and its radioactive decay also necessitates careful storage and disposal procedures to minimize environmental contamination.

Production:

As promethium is not found in large natural deposits, it is mainly produced artificially. One standard method involves extracting it from spent nuclear fuel, where it accumulates in small amounts. Another method is bombarding neodymium or praseodymium with neutrons in a nuclear reactor, which results in the production of promethium isotopes.

Applications:

Despite its rarity and radioactivity, promethium has some practical uses. One of its most notable applications is nuclear batteries, where promethium-147 is used as a power source for pacemakers, satellites, and other devices requiring a long-lasting, low-power energy supply. Promethium is also used in luminous paints, where its beta radiation excites phosphorescent materials, producing a glow without needing an external power source. Additionally, promethium can be employed in research settings, particularly in studying the chemistry of rare earth elements and radioactive decay processes.

Summary:

Promethium is not abundant or widely used but it is crucial in specific specialized applications, mainly where its radioactive properties are advantageous. However, its use requires stringent safety measures due to its inherent health and environmental risks.

See a comprehensive list of atomic, electrical, mechanical, physical and thermal properties for promethium below: