Quick Facts
| Property | Value |
|---|---|
| Symbol | Tc |
| Atomic Number | 43 |
| Atomic Mass | [98] u |
| Category | Transition Metal |
| Period | 5 |
| Group | 7 |
| Block | d |
| Electron Configuration | [Kr] 4d⁵ 5s² |
Physical Properties
| Property | Value |
|---|---|
| State at 20°C | Solid |
| Density | 11.0 g/cm³ |
| Melting Point | 2157°C (2430 K) |
| Boiling Point | 4265°C (4538 K) |
| Appearance | Silvery-gray metal |
Atomic Properties
| Property | Value |
|---|---|
| Electron Configuration | [Kr] 4d⁵ 5s² |
| Electronegativity | 1.9 (Pauling scale) |
| First Ionization Energy | 702 kJ/mol |
| Atomic Radius | 136 pm |
| Covalent Radius | 147 pm |
| Van der Waals Radius | 205 pm |
History and Discovery
Discovered by: Carlo Perrier and Emilio Segrè Year of Discovery: 1937 Location: Palermo, Italy
Etymology
Named from the Greek "technetos" meaning "artificial," as it was the first artificially produced element.
Discovery Story
Dmitri Mendeleev predicted the existence of "eka-manganese" in 1871. Carlo Perrier and Emilio Segrè discovered technetium in 1937 in a sample of molybdenum that had been bombarded with deuterons in a cyclotron. It was the first element to be produced artificially.
Isotopes
| Isotope | Natural Abundance | Half-life | Decay Mode |
|---|---|---|---|
| ⁹⁷Tc | Trace | 4.2 million years | EC |
| ⁹⁸Tc | Trace | 4.2 million years | β⁻ |
| ⁹⁹Tc | Trace | 211,000 years | β⁻ |
| ⁹⁹ᵐTc | Synthetic | 6.01 hours | IT, γ |
All technetium isotopes are radioactive. No stable isotopes exist.
Occurrence
Natural Abundance
Technetium is extremely rare in nature—only trace amounts exist from spontaneous fission of uranium. It is primarily produced artificially in nuclear reactors and particle accelerators.
Extraction and Production
- Fission Product: From uranium-235 fission in nuclear reactors
- Neutron Activation: Of molybdenum-98
- Sources: Nuclear fuel reprocessing
- Production: Several hundred kilograms accumulated worldwide
Applications and Uses
Nuclear Medicine
- Technetium-99m for diagnostic imaging (most common medical radioisotope)
- SPECT imaging (brain, heart, bones, kidneys)
- Cancer detection
- About 30 million procedures annually worldwide
Scientific Research
- Corrosion studies
- Nuclear waste research
- Superconductivity research
Industrial Applications
- Corrosion inhibitor for steel (research stage)
- Calibration of particle detectors
Biological Role
Technetium has no biological role. It is radioactive and would not occur naturally in organisms.
In the Human Body
Technetium-99m is used medically for imaging but is quickly excreted and has a short half-life.
Medical Importance
The 6-hour half-life of Tc-99m makes it ideal for medical imaging—long enough to perform procedures, short enough to minimize radiation exposure.
Safety and Hazards
Toxicity
All technetium isotopes are radioactive. Tc-99 emits beta radiation. Chemical toxicity is less concerning than radiological hazards.
Handling Precautions
- Radioactive material requires licensed handling
- Shielding and containment necessary
- Follow strict radioactive material protocols
- Beta radiation is easily shielded but internal exposure is hazardous
Environmental Impact
Technetium from nuclear waste and medical use can enter the environment. Tc-99 has a long half-life and is mobile in the environment.
Interesting Facts
- Technetium was the first artificially produced element
- Tc-99m is the most commonly used radioisotope in medicine
- Despite being artificial, trace amounts do exist naturally from uranium fission
- Technetium has no stable isotopes—the lightest such element
- A technetium generator (containing Mo-99) is called a "moly cow"