Tellurium has roles in alloys, semiconductors, and optical recording materials. Small additions can improve how copper or steel is machined. It is also used in solar-cell materials. Much commercial tellurium is recovered during copper refining, connecting electronic technologies to metal-processing by-products.
FROM ELEMENT TO APPLICATION
AN ELEMENT IN CONTEXT
How does a cadmium telluride absorber contribute to a complete solar cell?
Cadmium telluride semiconductor
FOLLOW THIS RELATIONSHIP
Bring sunlight into the absorber
A cadmium telluride semiconductor layer absorbs useful portions of incoming sunlight. The optical interaction occurs in a compound rather than isolated cadmium or tellurium.
Explore the model (optional)
TeFORM → INTERACTION → CONSEQUENCE
Follow the explanation in either direction. These are authored steps, not a physical clock.
Optional: check your understanding
USE THE EXPLANATION
Why is a CdTe crystal alone not a complete solar module?
Atomic identity, reference properties and structure models
INTERACTIVE 3D52 visible sites
An electron censusDrag to rotate · scroll or pinch to zoom
[Kr] 4d10 5s2 5p4. Grouping electrons by principal shell connects the neutral-atom configuration to periodic-table patterns.
What this representation means
A three-dimensional counting diagram. Dots are count markers, not measured electron positions; spherical placement and spacing are arbitrary. There are no electron trajectories here. Orbitals describe quantum states.
Franz Joseph Müller von Reichenstein investigated an unusual gold-bearing in the 1780s after familiar identifications failed. His evidence pointed to a new element, but recognition spread slowly. Martin Heinrich Klaproth later confirmed the finding and named tellurium. The case distinguishes observation from acceptance: a chemically sound discovery can remain obscure until another investigator examines material and makes the evidence more widely accessible.
1780s
Unfamiliar ore constituent identified
Müller investigated tellurium-bearing gold ore.
1790s
Confirmation and naming
Klaproth confirmed the new element and introduced tellurium.
Tellurium occurs in telluride , including gold-bearing calaverite, and can also occur in native form. Practical recovery is associated with residues from copper . This links tellurium to two different stories: minerals that attracted attention because of gold and industrial streams organized around a much more metal.
Tellurium has semimetallic behavior and forms compounds with useful electronic properties. Cadmium telluride is a , while small tellurium additions can change how copper are machined. The element's location near the metal–nonmetal boundary is a starting point for comparison, not a complete prediction of every compound's performance.
Each section links its supporting references. Descriptions and diagrams were authored for this atlas. Source checks completed. Source checks dated 2026-09-06.
CITE THIS PAGE
Family labels and the group-3 layout are teaching conventions. A table position does not establish an unknown bulk property. Electronic configurations refer to neutral atoms; ions and material environments require their own account.
Read each reference property together with its units, conditions and the reference information below.
Not yet recorded: electron affinity, second ionization energy, ground-state term symbol, van der waals radius, thermal conductivity, specific heat capacity, electrical resistivity, crystal structure, lattice parameter a, space group, abundance in seawater, abundance in the universe, annual production, supply-risk listing, hazard classification, biological role, cas registry number, pubchem cid, wikidata item. These families are declared and awaiting an ingestion run against the source each names; they are listed here rather than shown as empty rows.
Physical
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Phase at 20 °C
solid
293.15 K, 101.325 kPa
Melting point in K
722.66 K
at standard pressure unless noted
Boiling point in K
1261 K
101.325 kPa
Density in g/cm³
6.23 g/cm³
solids and liquids at 293 K; gases at 273 K and 101.325 kPa
Atomic and electronic
Intended reference: Pauling electronegativity scale · Widely tabulated; original in The Nature of the Chemical Bond
Electronegativity in Pauling
2.1 Pauling
Pauling scale
First ionization energy in kJ/mol
869.3 kJ/mol
gas-phase neutral atom, ground state
Covalent radius in pm
138 pm
single-bond covalent radius
Common oxidation states
-2, +4, +6
states met in ordinary compounds; not exhaustive
Occurrence and identity
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Abundance in the crust in mg/kg
0.001 mg/kg
upper continental crust, mass fraction
Has stable isotopes
Yesderived
Discovery year in CE
1785 CEderived
WHERE IT SITS AMONG ITS NEIGHBORS
Electronegativity across period 5
Te 2.1 Pauling · Tellurium
Electronegativity across period 5. Exact values.
Rb
0.82
Sr
0.95
Y
1.22
Zr
1.33
Nb
1.6
Mo
2.16
Tc
1.9
Ru
2.2
Rh
2.28
Pd
2.2
Ag
1.93
Cd
1.69
In
1.78
Sn
1.96
Sb
2.05
Te
2.1
I
2.66
Xe
2.6
Electronegativity down group 16
Te 2.1 Pauling · Tellurium
Electronegativity down group 16. Exact values.
O
3.44
S
2.58
Se
2.55
Te
2.1
Po
2
The trend uses the same reference-property values as the periodic table. Elements with no recorded value are left out of the line rather than drawn at zero.
