Technetium
Definition and meaning of Technetium in chemistry.
Technetium is a silvery-gray, radioactive transition metal with the chemical symbol Tc and an atomic number of 43. It holds the unique distinction of being the lowest atomic number element in the periodic table that has exclusively radioactive isotopes and no stable forms.
In more detail
Located in group 7 and period 5 of the periodic table, technetium lies directly between molybdenum and ruthenium and is artificially produced in nuclear reactors through the fission of uranium-235. Nearly all technetium present on Earth is synthetic, as its most stable isotope, technetium-98, has a half-life of only 4.2 million years, causing any primordial quantities to have decayed long before the formation of the current biosphere. Its chemical properties closely mirror its vertical neighbors in the periodic table, exhibiting characteristics intermediate between rhenium and manganese, commonly featuring stable oxidation states of +4 and +7. The pure metal slowly tarnishes in moist air to form stable oxides and dissolves readily in oxidizing acids like nitric acid or concentrated sulfuric acid, but remains impervious to hydrochloric acid. Because of its intense radioactivity and scarcity, macroscopic quantities of the metal are rarely studied outside specialized handling facilities, yet its unique nuclear emission properties make it completely invaluable in diagnostic medical imaging.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Tc |
| Atomic number | 43 |
| Atomic mass | [98] u |
| Category | Transition Metal |
| State at room temperature | Solid |
| Melting point | 2157 °C |
| Boiling point | 4265 °C |
| Year discovered | 1937 |
The metastable isotope technetium-99m is widely used as a radioactive tracer in nuclear medicine for imaging bones and internal organs due to its highly optimal short half-life of six hours.
Frequently asked questions
Can technetium be found in nature?
Trace amounts occur naturally in uranium ores as a product of spontaneous fission and in some red giant stars where it is actively produced by stellar nucleosynthesis.
Why was technetium difficult to discover?
Its lack of stable isotopes meant it did not exist in significant quantities on Earth, requiring the invention of particle accelerators to finally create and identify it artificially.