Technetium (Tc)
Isotopes of Technetium
| Isotope | Atomic Mass | Half-life | Mode of Decay | Nuclear Spin | Nuclear Magnetic Moment |
| Tc-93 | 92.910248 | 2.73 hours | EC to Mo-93 | 9/2 | 6.26 |
| Tc-94 | 93.909655 | 4.88 hours | EC to Mo-94 | 7 | 5.08 |
| Tc-95 | 94.90766 | 20.00 hours | EC to Mo-95 | 9/2 | 5.89 |
| Tc-96 | 95.90787 | 4.30 days | EC to Mo-96 | 7 | 5.04 |
| Tc-97 | 96.906364 | 2.60 x 106 years | EC to Mo-97 | 9/2 | No data available |
| Tc-98 | 97.907215 | 4.20 x 106 years | β- to Ru-98 | 6 | No data available |
| Tc-99 | 98.907 | 213,000 years | β- to Ru-99 | 9/2 | 5.6847 |
Technetium was discovered in 1936 by Carlo Perrier and Emilio Segrè. Its name comes from the Greek word technetos, meaning “artificial.” It is the lowest atomic number element without any stable isotopes; every form of technetium is radioactive.
Technetium is a silver-gray metal with a hexagonal close-packed crystal structure. Its chemical properties are intermediate between those of rhenium and manganese. Technetium dissolves in aqua regia, nitric acid and concentrated sulfuric acid, but it is not soluble in hydrochloric acid. The metal form is slightly paramagnetic, tarnishes slowly in moist air and, in powder form, will burn in oxygen.
Only minute traces of technetium occur naturally in the Earth's crust. Small amounts exist as spontaneous fission products in uranium ores. Some red giant stars are indicated to contain technetium — these are known informally as “technetium stars.” In contrast with its rare natural occurrence, bulk quantities of the isotope Technetium-99 are produced each year from spent nuclear fuel rods.
The metastable isotope Technetium-99m is used in nuclear medicine for a wide variety of diagnostic tests, including imaging and functional studies of the brain, myocardium, thyroid, lungs, liver, gallbladder, kidneys, skeleton, blood and tumors. Technetium-99 is a United States National Institute of Standards and Technology (NIST) standard beta emitter and is therefore used for equipment calibration. Technetium can be used as a catalyst, although its radioactivity limits the safety of these applications.
Properties of Technetium
| Name | Technetium |
| Symbol | Tc |
| Atomic number | 43 |
| Atomic weight | 98 |
| Standard state | Solid at 298 ºK |
| CAS Registry ID | 7440-26-8 |
| Group in periodic table | 7 |
| Group name | None |
| Period in periodic table | 5 |
| Block in periodic table | d-block |
| Color | Silvery gray metallic |
| Classification | Metallic |
| Melting point | 2157 °C |
| Boiling point | 4265 °C |
| Thermal conductivity | 50.6 W/(m·K) |
| Electronegativity | 1.9 |
| Heat of vaporization | 585.2 kJ·mol-1 |
| Heat of fusion | 33.29 kJ·mol-1 |
| Density of solid | 11 g/cm3 |
| Electron configuration | [Kr]4d55s2 |
| Oxidation states | -3, -1, +1, +2, +3, +4, +5, +6, +7 |
Research
- Highly selective colorimetric and luminescence response of a square-planar platinum(II) terpyridyl complex to aqueous TcO4–
- Cardiac stress testing and the radiotracer supply chain
- High-Resolution 4D Preclinical Single-Photon Emission Computed Tomography/X-ray Computed Tomography Imaging of Technetium Transport within a Heterogeneous Porous Media