Periodic Table


Atomic number: 52
Atomic weight: 127.60
Symbol: Te
Group number: 16
Electronic configuration: [Kr].4d10.5s2.5p4


Crystalline tellurium has a silvery-white appearance, and exhibits a metallic lustre when pure. It is brittle and easily pulverised. Tellurium is a p-type semiconductor, and shows varying conductivity with crystal alignment. Its conductivity increases slightly with exposure to light. It can be doped with silver, copper, gold, tin, or other elements.

Humans exposed to as little as 0.01 mg m-3 in air, or less, develop "tellurium breath", which has a garlic-like odour.

General information

Discoveror: Franz Joseph Muller von Reichstein
Date discovered: 1783
Discovered at: Romania
Meaning of name: From the Latin word "tellus" meaning "earth"

Physical data

Standard state: solid at 298 K
Colour: silvery lustrous grey
Density of solid at ambient temperature/kg m-3: 6240
Molar volume/cm3: 20.46

Radii /pm

Atomic: 123
Covalent (single bond):
Pauling radius for the ion [Te]-: 250

Valence shell orbital radius maxima (Rmax)
orbital s p d f
radius100.4116.942.8no data


Both values are quoted on the Pauling scale.

Pauling: 2.1
Allred Rochow: 2.01

Crystal Structure

structure: trigonal

The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.


Temperatures (/K)

melting point: 722.66
boiling point: 1261

Enthalpies /kJ mol-1

fusion: 17.5
vaporization: 48

single bond enthalpies:
Te-F Te-Cl Te-Br Te-I Te-Te
330 311 176 121 259.8

Ionization enthalpies /kJ mol-1

Number Enthalpy


This section gives some data for naturally occurring isotopes.
Nominal mass Accurate mass % natural abundance
120Te119.904048 (21)0.096 (2)
122Te121.903050 (3)2.60 (4)
123Te122.9042710 (22)0.908 (2)
124Te123.9028180 (18)4.816 (6)
125Te124.9044285 (25)7.14 (6)
126Te125.9033095 (25)18.95 (1)
128Te127.904463 (4)31.69 (1)
130Te129.906229 (5)33.80 (1)

Further Information

Copyright 1997 Mark Winter
Department of Chemistry at the University of Sheffield, Sheffield S3 7HF, England.

The current version of this document is at http://www.shef.ac.uk/~chem/web-elements-I/Te.html