Tellurium
[Kr] 4d¹⁰ 5s² 5p⁴ · 2 · 8 · 18 · 18 · 6
A rare metalloid named after the Earth. Tellurium is far more abundant in the universe than in Earth's crust: its volatile compounds escaped as the planet formed, leaving it one of our rarest elements.
3D model
Bohr model: nucleus and electron shells from the real configuration. Valence electrons are highlighted.
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Atomic properties
- Atomic number
- 52
- Atomic mass
- 127.6 а.е.м.
- Electron configuration
- [Kr] 4d¹⁰ 5s² 5p⁴
- Electrons per shell
- 2 · 8 · 18 · 18 · 6
- Block
- p-block
- Group
- Chalcogens
- Period
- 5
- Electronegativity (Pauling)
- 2.1
- Electronegativity (Allen)
- 2.16
- Atomic radius
- 123 pm
- Covalent radius
- 138 pm
- Van der Waals radius
- 206 pm
- Ionisation energy 1
- 869.3 kJ/mol
- Ionisation energy 2
- 1 790 kJ/mol
- Ionisation energy 3
- 2 698 kJ/mol
- Ionisation energy 4
- 3 610 kJ/mol
- Ionisation energy 5
- 5 668 kJ/mol
- Electron affinity
- 190.2 kJ/mol
- Common oxidation states
- -2, +4, +6
- Oxidation states
- -2, -1, +1, +2, +3, +4, +5, +6
Physical properties
- State at 25 °C
- solid
- Density
- 6.24 g/cm³
- Melting point
- 722.66 K · 449.5 °C
- Boiling point
- 1 261 K · 987.9 °C
- Speed of sound
- 2 610 m/s
Thermal properties
- Heat of fusion
- 17.49 kJ/mol
- Heat of vaporisation
- 114.1 kJ/mol
- Specific heat capacity
- 0.202 J/(g·K)
- Thermal conductivity
- 2.35 W/(m·K)
Mechanical properties
- Young's modulus
- 43 GPa
- Shear modulus
- 16 GPa
- Bulk modulus
- 65 GPa
- Poisson ratio
- 0.33
- Mohs hardness
- 2.25
- Brinell hardness
- 180 MPa
Electrical and magnetic properties
- Electrical resistivity
- 10 000 nΩ·m
- Magnetic ordering
- diamagnetic
- Curie point
- no data
- Néel point
- no data
- Superconducting point
- no data
Crystal structure
- Crystal structure
- hexagonal close-packed (hcp)
- Lattice constants
- a = 445.72 pm · c = 592.9 pm
Abundance
- In the crust
- 0.001 mg/kg
- In the ocean
- 0 mg/L
- In the universe
- 0.009 mg/kg
- In the human body
- 0.008 mg/kg
Isotopes
| Isotope | Abundance | Half-life | Decay mode |
|---|---|---|---|
| 120Te | 0.09 % | stable | — |
| 122Te | 2.55 % | stable | — |
| 123Te | 0.89 % | stable | — |
| 124Te | 4.74 % | stable | — |
| 125Te | 7.07 % | stable | — |
| 126Te | 18.84 % | stable | — |
| 128Te | 31.74 % | 2.218·10¹⁵ Gyr | 2β− |
| 130Te | 34.08 % | 7.922·10¹¹ Gyr | 2β− |
Tellurium-128 has a double beta decay half-life of 2·10²⁴ years — the longest half-life ever measured for any nuclide.
Discovery
- Year of discovery
- 1782
- Discovered by
- Franz-Joseph Müller von Reichenstein
- Where
- Romania
- Origin of the name
- from Latin tellus (earth)
History
Müller von Reichenstein found it in 1782 in Transylvanian gold ore and called it a paradoxical metal, unable to place it. Klaproth confirmed the discovery in 1798 and named it from Latin tellus, earth.
Where it occurs
0.001 mg/kg of the crust — scarcer than platinum. It occurs in gold and silver tellurides.
How it is produced
From the anode slimes of copper electrolysis, the same place selenium comes from. World output is a few hundred tonnes a year.
Role in living things
No biological role. The body methylates tellurium and exhales the product.
Safety
Even microscopic amounts produce a persistent garlic odour on the breath and skin that lasts for weeks. Tellurium compounds are toxic.
Uses
- Cadmium telluride — the second most common solar module material after silicon
- Bismuth telluride thermoelectrics: every compact Peltier cooler
- Phase-change materials in rewritable optical discs and PCM memory
- Alloying steel and copper to improve machinability
Curiosities
- Tellurium-128 holds the outright longevity record: its half-life is 160 trillion times the age of the universe.
- Tellurium and selenium are named after the Earth and the Moon.
- Tellurium has a higher atomic mass than iodine despite a lower number — one of the anomalies that made Mendeleev order by properties rather than by mass.
- Working with tellurium leaves a garlic odour that will not wash off for weeks.