Polonium, discovered in 1898 by Marie Curie and her husband Pierre Curie, stands as a monumental achievement in the realm of chemistry and physics.
This discovery was a pivotal moment in the understanding of radioactivity, a field that would lead to significant advancements in science and medicine.
The Curies’ investigation into pitchblende, a uranium-rich mineral, unveiled this new element, characterized by its intense radioactivity. Marie Curie, driven by a profound sense of patriotism, named the element polonium in honor of her native country, Poland, which was under foreign domination at the time.
Quick Reference of Polonium
- Symbol: Po
- Atomic Number: 84
- Atomic Weight: [209]
- Element Classification: Metalloid
- Discovered By: Marie Curie and Pierre Curie
- Discovery Date: 1898
- Name Origin: Named after Poland, the native country of Marie Curie
- Density (g/cc): 9.196 (calculated)
- Melting Point: 254°C
- Boiling Point: 962°C
- Appearance: Silvery-gray metal
- Atomic Radius (pm): 135 (estimated)
Relation to Other Elements
Polonium belongs to the chalcogen group, which includes oxygen, sulfur, selenium, and tellurium. While it shares some properties with its group neighbors, it is unique due to its radioactivity. Polonium has 33 known isotopes, all of which are radioactive. The most stable isotope, polonium-209, has a half-life of 125.2 years. Depending on the allotrope and physical conditions, polonium exhibits metallic, nonmetallic, and semiconductor properties.
Natural Occurrence
Polonium is extremely rare in nature and typically found in uranium ores at concentrations of up to 0.1 mg per ton. It forms as a decay product of uranium-238 and is more commonly produced in nuclear reactors by bombarding bismuth-209 with neutrons. This artificial production is necessary to meet the demand for polonium in various specialized applications.
Uses of Polonium
Due to its intense radioactivity and scarcity, polonium’s applications are limited and highly specialized:
Industrial Radiography
Polonium serves as a portable source of neutrons and alpha particles. These properties make it invaluable for industrial radiography, allowing for the inspection of welded joints and metal parts to detect structural weaknesses or faults.
Thermoelectric Power
Polonium’s heat released from radioactive decay has been harnessed to generate thermoelectric power in space missions. This application was crucial for powering satellites and lunar stations, where long-lasting and reliable heat sources are necessary for sustained operation.
Anti-static Devices
Polonium has been used in devices designed to eliminate static charges in machinery and processes where dust attraction is problematic. This application is particularly useful in the manufacturing of photographic films and synthetic fibers, where static can cause significant production issues.
Historical Significance and Nobel Prizes
The discovery of polonium was a milestone in the study of radioactivity, contributing to the awarding of two Nobel Prizes to Marie Curie: one in Physics (shared with Pierre Curie and Henri Becquerel) and another in Chemistry. This recognition solidified the Curies’ place in scientific history and underscored the importance of their work.
Safety and Handling of Polonium
Due to its high radioactivity, handling polonium requires strict safety measures. Polonium’s radioactivity poses significant health risks, including the potential for radiation poisoning. Therefore, its use is restricted to areas where its unique properties are indispensable, and stringent protocols are followed to ensure the safety of those who work with it.
Conclusion
The discovery of polonium by Marie and Pierre Curie in 1898 marked a significant advancement in the scientific community’s understanding of radioactivity. This element, named in a patriotic gesture by Marie Curie, continues to play a role in specialized applications due to its unique properties. While polonium’s intense radioactivity and rarity limit its use, its contributions to industrial radiography, thermoelectric power, and anti-static devices underscore its importance. The Curies’ work not only expanded the periodic table but also laid the groundwork for future research and applications in the field of radioactivity. Their legacy endures, inspiring new generations of scientists to explore and understand the mysteries of the natural world.