Technetium is a chemical element having atomic number 43 and symbol Tc, found in minute quantities in the earth's crust, and now, primarily produced synthetically. Its discovery is credited to the scientists Carlo Perrier and Emilio Segre in the year 1937, although the search went on for many years. It was the missing element responsible for the gap in the periodic table between molybdenum (element number 42) and ruthenium (element number 44). It is now produced artificially, and has industrial and chemical applications. It is also used in nuclear medicine and biology.
This element is a silvery, gray-colored, stable metal, which tarnishes on exposure to moisture in the air. It remains solid at room temperature. Its melting point is 3914.6°F, while its boiling point is 7709°F. In physical appearance, it resembles platinum, and it is radioactive in nature.
Since it is located in the seventh group of the periodic table between rhenium and manganese, its chemical properties fall in between these two chemical elements, though it resembles rhenium more than it does manganese. It dissolves in aqua regia (nitro-hydrochloric acid), nitric acid, and concentrated sulfuric acid. It does not dissolve in hydrochloric acid.
One of the many interesting facts about this element is that it is the one with the lowest atomic number in the periodic table, to have unstable isotopes (all its isotopes are radioactive). The only other element to display this behavior is promethium (atomic number 61). Typically, odd-numbered elements have fewer stable isotopes compared to their even-numbered counterparts. The most stable isotopes of this metal are technetium-97, 98, and 99.
Since this element is rare naturally, it is produced as a byproduct in the operations of nuclear reactors. Specifically, technetium-99 is produced by the nuclear fission of uranium-235 as well as plutonium-235. As a result, it is present in radioactive waste, and is also produced on the detonation of nuclear weapons. More than two-thirds of its global supply is handled by the Chalk River reactor in Ontario, Canada, and the Petten reactor in the Netherlands.
The three of the isotopes of this metal have significantly-long half-lives, each exceeding 2 million years, with technetium-99 exhibiting a half-life of 211,000 years. The half-life of an element is the time taken for it to reduce to half by decay. As a result, the disposal of this element is a valid and very real environmental concern. It is found in the waste material, mainly near defense-related facilities, academic institutions, and research facilities, as well as facilities with nuclear reactors. Current regulations prevent the release of around more than 90 TBq, which is approximately 309 lbs per year. Research facilities are involved in the exploration of techniques for its suitable disposal, which will reduce environmental issues.
It is used in nuclear medicine to carry out a number of medical tests, mainly related to imaging and functional studies of internal bodily organs, like bone scan. It is also used industrially for equipment calibration following its approval as a standard beta emitter. In the chemical industry, it functions as an effective catalyst, but its radioactive nature poses a practical problem. Owing to its radioactivity, precautions such as wearing a fume hood must be taken when handling it.
The discovery of this element and its subsequent application have helped in the advancement of medical tests and tools. I hope this article helped you to understand its elusive nature.