Properties and Overview of Polonium

Overview:

Polonium (Po) with the chemical symbol Po and atomic number 84, is a rare and highly radioactive element that captivates with its unique physical and chemical properties. Belonging to the chalcogen group in the periodic table, it was discovered in 1898 by Marie and Pierre Curie, making it the first element to be identified purely by its radioactivity. Named after Marie Curie's homeland, Poland, polonium is most commonly found in uranium ores, where it occurs in very small quantities as a decay product of uranium-238. Physically, polonium is a silvery-gray metal that exhibits a metallic luster when freshly prepared. It has a density of about 9.32g/cm³, which is slightly higher than that of lead. Polonium has a relatively low melting point for a metal, at around 254°C, and it sublimates, or transitions directly from a solid to a gas, at about 962°C. The element exists in several allotropes, but the most stable form at room temperature has a simple cubic crystal structure. One of the unique features of polonium is its intense radioactivity, which causes it to glow faintly blue due to the excitation of surrounding air molecules.
Chemically, polonium is similar to its lighter chalcogen analogs, such as tellurium and selenium, but it is more metallic in character. It can form compounds in the +2 and +4 oxidation states, with the +4 state being more stable. Polonium reacts readily with halogens to form polonium dihalides, such as polonium dichloride (PoCl₂) and polonium tetrafluoride (PoF₄). It also forms oxides like polonium dioxide (PoO₂) when exposed to oxygen. Due to its high radioactivity, polonium tends to self-oxidize, which complicates its handling and storage. The chemistry of polonium needs to be better explored because of its scarcity and the extreme precautions required to study it safely.
The extreme hazards of polonium, primarily its intense radioactivity, underscore the need for strict safety measures. The most common isotope, polonium-210, emits alpha particles, which are highly energetic but do not penetrate the skin. However, if polonium is ingested or inhaled, it poses a severe health risk. The ingestion of even a microgram of polonium-210 can be fatal, as it causes massive internal damage by irradiating tissues and organs. This makes polonium one of the most toxic substances known. Handling polonium requires specialized facilities equipped with proper ventilation, containment, and monitoring systems to prevent accidental release or contamination. Because of its toxicity and the fact that it can be easily absorbed through wounds or inhaled as dust, stringent safety protocols must be followed. In addition to its radiological hazards, polonium is chemically toxic, similar to other heavy metals, which further complicates its handling.

Production:

Due to its scarcity in nature, polonium production is limited. Most polonium is produced artificially in nuclear reactors by bombarding bismuth-209 with neutrons, resulting in bismuth-210, which decays to polonium-210. The production process involves separating polonium from the irradiated bismuth target, a complex and hazardous operation due to the element's high radioactivity. The quantities of polonium produced are typically tiny, reflecting its limited applications and the extreme care required in its handling.

Applications:

Polonium has a few specialized applications, primarily due to its radioactive properties. One of its primary uses is in static eliminators, where polonium-210 ionizes air. It neutralizes static electricity in environments where it can be problematic, such as in manufacturing sensitive electronic components. These devices take advantage of the alpha particles emitted by polonium, which ionize the surrounding air and help to dissipate static charges. Polonium-210 is also used as a heat source in radioisotope thermoelectric generators (RTGs) for space missions. However, this application is less common than plutonium-238 because of polonium's shorter half-life. In addition, polonium has been used in scientific research as a neutron source and in the study of alpha particle emissions.

Summary:

Polonium is a rare and highly radioactive element with unique physical and chemical properties. Its extreme radioactivity and toxicity make it a significant hazard, requiring specialized handling and production techniques. Despite its dangers, polonium has been found to have limited use in industry and scientific research, primarily because of its ability to emit alpha particles. However, the element's potential for misuse as a poison underscores the need for strict regulatory control and safety measures. Polonium remains one of the most intriguing and dangerous elements, with a complex legacy shaped by its discovery, uses, and the risks it poses.

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