Quick Facts
| Property | Value |
|---|---|
| Symbol | Te |
| Atomic Number | 52 |
| Atomic Mass | 127.60 u |
| Category | Metalloid |
| Period | 5 |
| Group | 16 |
| Block | p |
| Electron Configuration | [Kr] 4d¹⁰ 5s² 5p⁴ |
Physical Properties
| Property | Value |
|---|---|
| State at 20°C | Solid |
| Density | 6.24 g/cm³ |
| Melting Point | 449.51°C (722.66 K) |
| Boiling Point | 988°C (1261 K) |
| Appearance | Silvery-white, brittle, crystalline |
Atomic Properties
| Property | Value |
|---|---|
| Electron Configuration | [Kr] 4d¹⁰ 5s² 5p⁴ |
| Electronegativity | 2.1 (Pauling scale) |
| First Ionization Energy | 869.3 kJ/mol |
| Atomic Radius | 140 pm |
| Covalent Radius | 138 pm |
| Van der Waals Radius | 206 pm |
History and Discovery
Discovered by: Franz-Joseph Müller von Reichenstein Year of Discovery: 1783 Location: Transylvania (modern Romania)
Etymology
Named from Latin "tellus" meaning "earth" or "ground." Martin Heinrich Klaproth named it in 1798.
Discovery Story
Franz-Joseph Müller von Reichenstein discovered tellurium in 1783 while analyzing gold ore from Transylvania. He recognized it as a new element but could not isolate it. Martin Heinrich Klaproth confirmed the discovery in 1798 and named it tellurium.
Isotopes
| Isotope | Natural Abundance | Half-life | Decay Mode |
|---|---|---|---|
| ¹²⁰Te | 0.09% | Stable | - |
| ¹²²Te | 2.55% | Stable | - |
| ¹²³Te | 0.89% | >9.2 × 10¹⁶ years | EC |
| ¹²⁴Te | 4.74% | Stable | - |
| ¹²⁵Te | 7.07% | Stable | - |
| ¹²⁶Te | 18.84% | Stable | - |
| ¹²⁸Te | 31.74% | 2.2 × 10²⁴ years | β⁻β⁻ |
| ¹³⁰Te | 34.08% | 7.9 × 10²⁰ years | β⁻β⁻ |
Occurrence
Natural Abundance
Tellurium is very rare, comprising only about 0.001 ppm of Earth's crust (rarer than gold). It occurs in native form, telluride ores, and with copper and gold ores.
Extraction and Production
- Byproduct: Almost entirely from copper refining
- Anode Slimes: Recovered from electrolytic copper refining
- Sources: Copper smelters worldwide
- Global production: about 500 tons annually
Applications and Uses
Photovoltaics
- Cadmium telluride (CdTe) solar cells (fastest-growing use)
- Thin-film solar panels
- High efficiency at lower cost
Metallurgy
- Steel and copper alloys (improves machinability)
- Lead alloys (batteries)
- Cast iron additive
Thermoelectrics
- Bismuth telluride cooling devices
- Thermoelectric generators
- Solid-state refrigeration
Other Uses
- Vulcanizing agent for rubber
- Glass and ceramic colorant (blue)
- Infrared detectors
Biological Role
Tellurium has no known biological role and is toxic.
In the Human Body
Tellurium is not normally present in the body. Exposure causes "garlic breath" due to dimethyl telluride formation.
Toxicity
Tellurium compounds are toxic. Hydrogen telluride (H₂Te) is extremely poisonous.
Safety and Hazards
Toxicity
Tellurium and its compounds are moderately toxic. The characteristic "garlic breath" indicates exposure. More toxic than selenium.
Handling Precautions
- Avoid inhalation of dust
- Hydrogen telluride is extremely toxic
- "Tellurium breath" persists for weeks after exposure
- Use appropriate ventilation
Environmental Impact
Tellurium is rare. Solar panel recycling and electronic waste are emerging concerns for tellurium recovery.
Interesting Facts
- Tellurium was discovered before selenium, though selenium appears before it in the periodic table
- Exposure to tellurium causes persistent garlic-like breath odor
- Tellurium is rarer than gold in Earth's crust
- CdTe solar cells are among the lowest-cost solar technologies
- The element is named after Earth, while selenium (above it) is named after the Moon