Periodic table › Tellurium
1. Identity and classification
Brittle, crystalline solid with a metallic luster and semiconducting electrical properties
- Name and symbol
- Tellurium (Tellurium) · Te
- Atomic number
- 52
- Relative atomic weight / mass number
- 127.60 ± 0.03
- Group · period · block
- 16 · 5 · p
- Category
- Metalloid
- State near room temperature
- Solid
- Stable isotopes
- At least one stable isotope
- CAS number
- 13494-80-9
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
- 52 · 52
- Neutrons in reference isotope
- 78 (130Te)
- Full electron configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁴- Abbreviated configuration
[Kr]5s² 4d¹⁰ 5p⁴- Electrons per shell
- 2, 8, 18, 18, 6
- Listed oxidation states
- +6, +4, -2
- Electronegativity
- 2.1 (Pauling)
- First ionization energy
- 869.333 kJ/mol · 9.01 eV
- Electron affinity
- 190.173 kJ/mol
- Covalent radius
- 138 pm
- van der Waals radius
- 206 pm
Configurations of superheavy elements may include theoretical predictions. Different definitions of atomic radius are not interchangeable.
3. Physical and thermal properties
- Density
- 6.232 g/cm³
- Melting point
- 722.66 K · 449.51 °C · 841.118 °F
- Boiling point
- 1261 K · 987.85 °C · 1810.13 °F
- Crystal structure
- Hexagonal
- Specific heat
- 0.202 J/(g·K)
- Thermal conductivity
- 3 W/(m·K)
- Enthalpy of fusion
- 17.49 kJ/mol
- Enthalpy of vaporization
- 114.1 kJ/mol
- Magnetic ordering
- Diamagnetic
- Mohs hardness
- 2.25
- Speed of sound
- 2610 m/s
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: TeO / Te₂O₃ (Oxide) · TeClₙ (Chloride) · TeFₙ (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 |
|---|---|---|---|
| 120Te | Stable | 0.09% | Stable |
| 122Te | Stable | 2.55% | Stable |
| 123Te | Radioactive | 0.89% | GT 9.2E+16 Y |
| 124Te | Stable | 4.74% | Stable |
| 125Te | Stable | 7.07% | Stable |
| 126Te | Stable | 18.84% | Stable |
| 128Te | Radioactive | 31.74% | 7.7E+24 Y |
| 129Te | Radioactive | — | 69.6 m |
| 130Te | Radioactive | 34.08% | GT 0.79E+21 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
- 1782 CE
- Scientists associated with discovery
- Franz-Joseph Müller von Reichenstein
- Location
- Romania (Sibiu)
- Origin
- Natural
- Listed crustal abundance
- Not established
Minerals and naming reference
Calaverite, Sylvanite, copper electrorefining anode slimes
Named from scientific/historical roots associated with Tellurium (Te), discovered or characterized by Franz-Joseph Müller von Reichenstein.
7. Applications
Cadmium Telluride (CdTe) utility-scale solar panels, Bismuth Telluride (Bi₂Te₃) Peltier thermoelectric coolers, phase-change optical discs
Detailed applications by field
- everyday
- Cadmium Telluride (CdTe) utility-scale solar panels, Bismuth Telluride (Bi₂Te₃) Peltier thermoelectric coolers, phase-change optical discs
- industry
- Used in metalloid processing, specialized alloys, and chemical manufacturing (Cadmium Telluride (CdTe) utility-scale solar panels, Bismuth Telluride (Bi₂Te₃) Peltier thermoelectric coolers, phase-change optical discs).
- electronics
- Applied in electronic components, semiconductors, or functional coatings where Tellurium's electronic structure ([Kr] 4d¹⁰ 5s² 5p⁴) provides target conductivity.
- medicine
- Diagnostic imaging, biomedical instrumentation, or pharmaceutical synthesis research.
- energy
- Utilized in power generation, battery materials, catalysts, or nuclear technology involving Tellurium.
- aerospace
- High-performance materials, structural alloys, or space instrumentation utilizing Tellurium.
- agriculture
- Soil geochemistry analysis, trace micronutrient research, or analytical environmental monitoring.
- science
- Spectroscopic standard, crystallography, and quantum chemistry studies of Period 5 p-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 toxic in human and biological systems.