Periodic table › Technetium
1. Identity and classification
Lustrous, hard, high-density silvery or metallic solid with high tensile strength
- Name and symbol
- Technetium (Technetium) · Tc
- Atomic number
- 43
- Relative atomic weight / mass number
- [98]
- Group · period · block
- 7 · 5 · d
- Category
- Transition Metal
- State near room temperature
- Solid
- Stable isotopes
- No stable isotopes
- CAS number
- 7440-26-8
Square brackets [A] indicate a representative isotope mass number, not an average atomic weight. Neutron counts differ between isotopes.
2. Atomic structure and electron configuration
- Protons · electrons in a neutral atom
- 43 · 43
- Neutrons in reference isotope
- 55 (98Tc)
- Full electron configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁵ 5s²- Abbreviated configuration
[Kr]5s² 4d⁵- Electrons per shell
- 2, 8, 18, 13, 2
- Listed oxidation states
- +7, +6, +4
- Electronegativity
- 1.9 (Pauling)
- First ionization energy
- 702.413 kJ/mol · 7.28 eV
- Electron affinity
- 53.067 kJ/mol
- Covalent radius
- 147 pm
- van der Waals radius
- 209 pm
Configurations of superheavy elements may include theoretical predictions. Different definitions of atomic radius are not interchangeable.
3. Physical and thermal properties
- Density
- 11 g/cm³
- Melting point
- 2430 K · 2156.85 °C · 3914.33 °F
- Boiling point
- 4538 K · 4264.85 °C · 7708.73 °F
- Crystal structure
- HCP
- Specific heat
- 0.243 J/(g·K)
- Thermal conductivity
- 50.6 W/(m·K)
- Enthalpy of fusion
- 33.29 kJ/mol
- Enthalpy of vaporization
- 585.2 kJ/mol
- Magnetic ordering
- Paramagnetic
- Mohs hardness
- Not established
- Speed of sound
- Not established
Density and structure depend on temperature, pressure and allotrope. 25°C is a room-temperature reference, not STP. Unestablished values are not zero.
4. Chemical behavior and compounds
The listed electron configuration and oxidation states describe atomic structure; compound properties depend on bonding and composition.
Selected compounds: TcO / Tc₂O₃ (Oxide) · TcClₙ (Chloride) · TcFₙ (Fluoride)
Reaction reference
Oxidation behavior depends on temperature, surface passivation and the chemical environment.
Direct reaction with water is element- and condition-dependent.
5. Isotopes
| Isotope | Status | Natural abundance | Half-life |
|---|---|---|---|
| 98Tc | Radioactive | — | 4.2E+6 Y |
Half-life units: s seconds, m minutes, h hours, d days, Y years. A dash means no natural-abundance value is given, not zero. Listed records are selected ground states; metastable states are distinct.
6. Discovery and occurrence
- Discovery
- 1937 CE
- Scientists associated with discovery
- Carlo Perrier & Emilio Segrè
- Location
- Italy (Palermo)
- Origin
- Trace Natural / Synthetic
- Listed crustal abundance
- Not established
Minerals and naming reference
Trace spontaneous fission in uranium ores; reactor synthesis
Named from scientific/historical roots associated with Technetium (Tc), discovered or characterized by Carlo Perrier & Emilio Segrè.
7. Applications
Technetium-99m (⁹⁹ᵐTc) nuclear medicine SPECT imaging of heart, bone, brain, and kidneys (over 30 million diagnostic scans/year)
Detailed applications by field
- everyday
- Technetium-99m (⁹⁹ᵐTc) nuclear medicine SPECT imaging of heart, bone, brain, and kidneys (over 30 million diagnostic scans/year)
- industry
- Used in transition metal processing, specialized alloys, and chemical manufacturing (Technetium-99m (⁹⁹ᵐTc) nuclear medicine SPECT imaging of heart, bone, brain, and kidneys (over 30 million diagnostic scans/year)).
- electronics
- Applied in electronic components, semiconductors, or functional coatings where Technetium's electronic structure ([Kr] 4d⁵ 5s²) provides target conductivity.
- medicine
- Diagnostic imaging, biomedical instrumentation, or pharmaceutical synthesis research.
- energy
- Utilized in power generation, battery materials, catalysts, or nuclear technology involving Technetium.
- aerospace
- High-performance materials, structural alloys, or space instrumentation utilizing Technetium.
- agriculture
- Soil geochemistry analysis, trace micronutrient research, or analytical environmental monitoring.
- science
- Spectroscopic standard, crystallography, and quantum chemistry studies of Period 5 d-block elements.
8. Biological role and safety
Hazard depends on the isotope, chemical form, dose and exposure route.
Elemental substances, ions, compounds and radioisotopes can have different health effects. This is an educational reference; laboratory work requires the material safety data sheet and trained supervision.
Biological role reference
Classified as highly radioactive / synthetic in human and biological systems.