Properties and Overview of Technetium

Overview:

Technetium (Tc) with the chemical symbol Tc and atomic number 43, is a silvery-gray metal and was the first element to be produced artificially. Discovered in 1937 by Italian scientists Carlo Perrier and Emilio Segrè, technetium was isolated from a sample of molybdenum that had been bombarded with deuterons in a cyclotron, thus creating an isotope of the previously missing element 43. Its name, derived from the Greek word "technetos," meaning "artificial," reflects its artificial origin. Physically, technetium is a transition metal with properties similar to rhenium and manganese, its neighbors in the periodic table. It has a relatively high melting point of 2,157°C and a boiling point of approximately 4,265°C. Technetium is relatively dense, with a density of 11g/cm³. It resembles platinum with a metallic luster, but it is rarely encountered in its pure metallic form due to its radioactivity and scarcity.
Chemically, technetium behaves like other group 7 elements, forming compounds in multiple oxidation states, with +7, +5, and +4 being the most common. Technetium forms various compounds, including technetium oxides, halides, and organometallic complexes. One of its most important compounds is sodium pertechnetate (NaTcO₄), in which technetium is in the +7 oxidation state. This compound is highly soluble in water and is commonly used in radiopharmaceuticals. Technetium is also known to form coordination complexes with various ligands, making it useful in various chemical and medical applications.
In terms of safety, technetium poses certain risks due to its radioactivity. Technetium-99, with a half-life of approximately 211,000 years, emits low-energy beta particles, which are not highly penetrating but can be hazardous if ingested or inhaled. Technetium-99m, used in medical diagnostics, has a much shorter half-life and emits gamma radiation, which is helpful for imaging but also requires careful handling to minimize exposure. In a medical setting, the benefits of using technetium-99m generally outweigh the risks, as its short half-life minimizes the duration of radiation exposure. However, proper safety protocols are essential when working with technetium in any form to prevent contamination and limit radiation exposure.

Production:

Technetium is primarily produced as a byproduct of uranium fission in nuclear reactors. When uranium-235 undergoes fission, technetium-99, the most common isotope of technetium, is produced as one of the fission products. Technetium-99m, a metastable isomer of technetium-99, is essential in nuclear medicine due to its ideal characteristics for imaging, including its short half-life of about 6 hours and the emission of gamma rays, which are easily detectable by medical imaging devices. The production of technetium-99m typically involves irradiating molybdenum-98 (Mo-98) with neutrons in a nuclear reactor, creating molybdenum-99 (Mo-99), which decays to technetium-99m.

Applications:

Technetium's most prominent application is in nuclear medicine. Technetium-99m is the most widely used radioactive tracer in diagnostic imaging, particularly in procedures such as bone scans, cardiac stress tests, and the detection of cancers. Its ability to emit gamma rays allows for high-resolution imaging of internal organs, helping doctors diagnose and monitor various medical conditions. The isotope's short half-life ensures it decays quickly, reducing the overall radiation dose to the patient.
Outside of medicine, technetium has limited but notable applications. It is used in corrosion-resistant coatings for steel, especially in environments where materials are exposed to high temperatures and corrosive conditions, such as in nuclear reactors and aircraft. Technetium's addition to steel improves its resistance to oxidation and corrosion, making it valuable in critical industrial applications. Additionally, technetium has been explored as a component in some types of nuclear batteries, where its long half-life and ability to emit low-energy beta particles make it a potential energy source for long-duration space missions and other remote applications.

Summary:

Technetium is a unique transition metal with significant historical importance as the first artificially produced element. It has distinct physical and chemical properties, including high melting and boiling points and multiple oxidation states. Technetium is primarily produced as a byproduct of nuclear fission, with its most significant isotope, technetium-99m, playing a crucial role in nuclear medicine. While its radioactivity poses safety risks, particularly in handling and disposal, technetium's applications in medical diagnostics and industrial coatings underscore its value in specialized fields.

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