About

Tellurium is a brittle, silvery-white metalloid that is chemically related to selenium and sulfur. It is a p-type semiconductor and is often alloyed with other elements, such as steel and copper, to improve their machinability. It is also used to create specialized thermoelectric devices and in rewritable optical discs (CD-RW, DVD-RW). It is one of the rarest stable solid elements on Earth.

Atomic Properties

Atomic Number52

Atomic Weight127.6 u

Neutrons (common)76

Electron Configuration[Kr] 4d¹⁰ 5s² 5p⁴

Full Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁴

Electrons per Shell2, 8, 18, 18, 6

Electronegativity2.1

Electron Affinity190.16 kJ/mol

Oxidation States+6, +4, +2, -2

Covalent Radius138 pm

Van der Waals Radius206 pm

Ionic Radius97 pm

Periodic Table Position

Group16

Period5

BlockP

Chemical SeriesMetalloids

Physical Properties

State at STPsolid

Appearancesilvery-white lustrous metalloid

Crystal Structurerhombohedral

Magnetic Orderingdiamagnetic

Speed of Sound2,610 m/s

Poisson Ratio0.33

Thermal Properties

Melting Point722.66 K

Boiling Point1,261 K

Triple Point722.66 K

Thermal Expansion0 1/K

Thermal Conductivity2.35 W/(m·K)

Specific Heat0.202 J/(g·K)

Molar Heat25.73 J/(mol·K)

Heat of Fusion17.49 kJ/mol

Heat of Vaporization52.55 kJ/mol

Abundance

In Earth's Crust0.001 ppm

In Solar System0.009 ppm

In Universe0.009 ppm

Discovery

Discovered byFranz-Joseph Müller von Reichenstein

Discovery Year1,782

Occurrenceprimordial

CAS Number13494-80-9

Electron Configuration

Energy

↿⇂

↿

Isotopes of Tellurium

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
¹²⁰Te	119.904020	0.09%	Stable	Stable
¹²²Te	121.903050	2.55%	Stable	Stable
¹²³Te	122.904270	0.89%	600 Ty	Electron Capture
¹²⁴Te	123.902820	4.74%	Stable	Stable
¹²⁵Te	124.904430	7.07%	Stable	Stable
¹²⁶Te	125.903310	18.84%	Stable	Stable
¹²⁸Te	127.904460	31.74%	2.25 Zy	Double Beta Minus Decay
¹³⁰Te	129.906220	34.08%	791 Ey	Double Beta Minus Decay

Interactive Visualization

Explore the 3D Bohr model of Tellurium in our interactive viewer.

View 3D Model of Tellurium