Tellurium (Te)


Tellurium is a chemical element with the atomic number 52 in the periodic table. It’s an extremely rarely found element in Earth’s crust. Its occurrence can be compared with that of the element platinum.

Being a member of the chalcogen elements family of the periodic table, this rare, silver-white metalloid element possesses the chemical properties of both metals and nonmetals. Element 52 naturally occurs in many tellurium-rich minerals, such as the tellurates and tellurites. It forms numerous compounds that can often be found as natural complexes. 

Fact Box

Chemical and Physical Properties of Tellurium

The symbol in the periodic table of elements: Te

Atomic number: 52

Atomic weight (mass): 127.6 g.mol-1

Group number: 16 (Chalcogens)

Period: 5 (p-block)

Color: A crystalline, silvery-white semi-metal substance with luster

Physical state: Solid at room temperature

Half-life: From less than 18 nanoseconds to 8.2 (0.2 (stat.), 0.6 (syst.))×1020 years

Electronegativity according to Pauling: 2.1

Density: 6.24

Melting point: 449.51°C, 841.12°F, 722.66 K

Boiling point: 988°C, 1810°F, 1261 K

Van der Waals radius: 0.137 nm

Ionic radius: 0.221 nm (-2); 0.089 nm (+4)

Isotopes: 39

Most characteristic isotope: 130Te

Electronic shell: [Kr] 4d105s25p4

The energy of the first ionization: 869.0 kJ.mol-1

The energy of the second ionization: N/A

Discovery date: In 1783 by Franz Joseph Müller von Reichenstein

With the periodic table symbol Te, atomic number 52, atomic mass of 127.6 g.mol-1, and electron configuration [Kr] 4d105s25p4, tellurium is a crystalline, silvery-white semi-metal substance that shares the properties of both metal and the non-metal elements of the periodic table. It reaches its boiling point at 988°C, 1810°F, 1261 K, while the melting point is achieved at 449.51°C, 841.12°F, 722.66 K. 

Tellurium is classified as a member of the chalcogen (group 16) family of elements in the periodic table. It has an electronegativity of 2.1 according to Pauling, whereas the atomic radius according to van der Waals is 0.137 nm. 

With a hexagonal crystal structure and metallic luster, this semi-metallic element is a brittle substance that is unaffected by water or hydrochloric acid but easily dissolves in nitric acid. When exposed to air, tellurium burns in air with a greenish-blue flame and forms white tellurium dioxide (TeO2). In a chemical reaction with hydrogen, tellurium forms only one compound – hydrogen telluride. H2Te is a gas at room temperature.                 

How Was Tellurium Discovered?

Element 52 was discovered by the Austrian mining official and mineralogist Franz-Joseph Muller (1740-1825). During the 1700s, the chemists of that time were somewhat puzzled by the substance that could be traced in a wide range of minerals. They labeled it “aurum paradoxum” and ‘‘metallum problematum” because its chemical behavior resembled both the metals and the non-metals. 

In 1782, Muller conducted an analysis of Transylvanian gold ore. He decided to purify it, in an effort to prove his belief that this ore contains antimony. Today we know that this ore was actually gold telluride (AuTe2), also known as calaverite. The results he obtained from his experiment proved him wrong, but at the same time encouraged him to believe that he was en route to discovering a new element. 

Searching for additional scientific confirmation, Muller sent a sample of the substance he isolated to Swedish chemist and mineralogist Torbern Bergman (1735-1784) in Uppsala, Sweden. His fellow chemist agreed that the sample did not contain any antimony, and expressed an interest to do further research on the substance. Unfortunately, Bergman passed away soon after it. 

For some time, Franz-Joseph Muller was preoccupied with other researchers. In 1796, he renewed his interest in the substance with strange behavior and asked the German chemist Martin H. Klaproth (1743 – 1817) to help him clarify the mystery surrounding the new element. 

After two years of research on the sample in his Berlin laboratory, Martin Heinrich Klaproth was proud to present his findings on the new element of the periodic table, after successfully isolating the new substance. Klaproth named the new lament tellurium but gave all credits for the discovery of element 52 to Franz Joseph Müller von Reichenstein.

How Did Tellurium Get Its Name?

The name tellurium of element 52 originates from the Latin word ‘tellus‘, which is a term referring to Earth.

Where Can You Find Tellurium?

Tellurium mostly occurs in minerals, including krennerite, calaverite, and sylvanite. However, none of these minerals are mined as the main source of this chemical element. 

For commercial purposes, tellurium is most often obtained as a byproduct from the anode muds resulting from the electrolytic refining of blister copper. The world’s largest producers of tellurium are Japan, Peru, Canada, and the United States. 

List of Telluride Minerals 

The list of other tellurium-rich minerals includes the following items:


  • Altaite
  • Bilibinskite
  • Calaverite
  • Coloradoite
  • Empressite
  • Hessite
  • Honeaite
  • Kostovite
  • Krennerite
  • M
  • Melonite
  • Merenskyite
  • Petzite
  • Rickardite
  • Stützite
  • Sylvanite
  • Tellurobismuthite
  • Temagamite
  • Tetradymite
  • Vulcanite
  • Weissite

Tellurium in Everyday Life

Tellurium’s physical and chemical properties are most often used in the following instances:

  • When added to tin, lead, and aluminum, tellurium improves the machinability, resistance, strength, and durability of these alloys;
  • The electronic, semiconductor, and metallurgy industries apply tellurium in the production of thermoelectric devices, blasting caps, cast iron, chips, modulators, and optical discs;
  • Element 52 is often added to stainless steel and copper, and is also used as an oxidizer and colorant;
  • Tellurium is also added to lead to increase its strength and resistance to sulfuric acid (H2SO4);
  • Cadmium telluride (CdTe) is included in the production process of solar panels and solar cells;
  • In combination with mercury and cadmium, tellurium is used for the manufacturing of photosensitive conductors.

How Dangerous Is Tellurium?

When tellurium is ingested, our body transforms it into dimethyl telluride (a compound from the

telluroethers class). Upon exposure to tellurium fumes or any of its toxic compounds, this chemical may trigger side effects, such as nausea, loss of sweat gland function, headache, eye irritation, vomiting, constipation, abdominal pain, difficulty breathing, a garlic-like odor from the mouth (tellurium breath), or even tellurium poisoning. 

This chemical is also classified as a teratogen, i.e. a chemical agent that may disturb the proper development of the embryo or fetus. 

Environmental Effects of Tellurium

Tellurium is not considered a hazardous substance and doesn’t have any negative effects on the geological, biological, or aquatic systems of our environment. 

Isotopes of Tellurium

There are 39 isotopes of tellurium. The naturally occurring form of this chemical element consists of 8 isotopes, among which two are radioactive (128Te and 130Te). These two isotopes are also the most common forms of the chemical element 52. Stable isotopes make up only 33.2% of naturally occurring tellurium.


[n 1]

Z N Isotopic mass (Da)

[n 2][n 3]


[n 4][n 5]



[n 6]



[n 7]

Spin and


[n 8][n 5]

Natural abundance (mole fraction)
Excitation energy Normal proportion Range of variation
104Te[5] 52 52 <18 ns α 100Sn 0+
105Te 52 53 104.94364(54)# 620(70) ns α 101Sn 5/2+#
106Te 52 54 105.93750(14) 70(20) µs

[70(+20−10) µs]

α 102Sn 0+
107Te 52 55 106.93501(32)# 3.1(1) ms α (70%) 103Sn 5/2+#
β+ (30%) 107Sb
108Te 52 56 107.92944(11) 2.1(1) s α (49%) 104Sn 0+
β+ (48.5%) 108Sb
β+, p (2.4%) 107Sn
β+, α (.065%) 104In
109Te 52 57 108.92742(7) 4.6(3) s β+ (86.99%) 109Sb (5/2+)
β+, p (9.4%) 108Sn
α (7.9%) 105Sn
β+, α (.005%) 105In
110Te 52 58 109.92241(6) 18.6(8) s β+ (99.99%) 110Sb 0+
β+, p (.003%) 109Sn
111Te 52 59 110.92111(8) 19.3(4) s β+ 111Sb (5/2)+#
β+, p (rare) 110Sn
112Te 52 60 111.91701(18) 2.0(2) min β+ 112Sb 0+
113Te 52 61 112.91589(3) 1.7(2) min β+ 113Sb (7/2+)
114Te 52 62 113.91209(3) 15.2(7) min β+ 114Sb 0+
115Te 52 63 114.91190(3) 5.8(2) min β+ 115Sb 7/2+
116Te 52 64 115.90846(3) 2.49(4) h β+ 116Sb 0+
117Te 52 65 116.908645(14) 62(2) min β+ 117Sb 1/2+
118Te 52 66 117.905828(16) 6.00(2) d EC 118Sb 0+
119Te 52 67 118.906404(9) 16.05(5) h β+ 119Sb 1/2+
120Te 52 68 119.90402(1) Observationally Stable[n 9] 0+ 9(1)×10−4
121Te 52 69 120.904936(28) 19.16(5) d β+ 121Sb 1/2+
122Te 52 70 121.9030439(16) Stable 0+ 0.0255(12)
123Te 52 71 122.9042700(16) Observationally Stable[n 10] 1/2+ 0.0089(3)
124Te 52 72 123.9028179(16) Stable 0+ 0.0474(14)
125Te[n 11] 52 73 124.9044307(16) Stable 1/2+ 0.0707(15)
126Te 52 74 125.9033117(16) Stable 0+ 0.1884(25)
127Te[n 11] 52 75 126.9052263(16) 9.35(7) h β 127I 3/2+
128Te[n 11][n 12] 52 76 127.9044631(19) 2.2(3)×1024 y[n 13] ββ 128Xe 0+ 0.3174(8)
129Te[n 11] 52 77 128.9065982(19) 69.6(3) min β 129I 3/2+
130Te[n 11][n 12] 52 78 129.9062244(21) 8.2(0.2 (stat.), 0.6 (syst.))×1020 y ββ 130Xe 0+ 0.3408(62)
131Te[n 11] 52 79 130.9085239(21) 25.0(1) min β 131I 3/2+
132Te[n 11] 52 80 131.908553(7) 3.204(13) d β 132I 0+
133Te 52 81 132.910955(26) 12.5(3) min β 133I (3/2+)
134Te 52 82 133.911369(11) 41.8(8) min β 134I 0+
135Te[n 14] 52 83 134.91645(10) 19.0(2) s β 135I (7/2−)
136Te 52 84 135.92010(5) 17.63(8) s β (98.7%) 136I 0+
β, n (1.3%) 135I
137Te 52 85 136.92532(13) 2.49(5) s β (97.01%) 137I 3/2−#
β, n (2.99%) 136I
138Te 52 86 137.92922(22)# 1.4(4) s β (93.7%) 138I 0+
β, n (6.3%) 137I
139Te 52 87 138.93473(43)# 500 ms

[>300 ns]#

β 139I 5/2−#
β, n 138I
140Te 52 88 139.93885(32)# 300 ms

[>300 ns]#

β 140I 0+
β, n 139I
141Te 52 89 140.94465(43)# 100 ms

[>300 ns]#

β 141I 5/2−#
β, n 140I
142Te 52 90 141.94908(64)# 50 ms

[>300 ns]#

β 142I 0+

Source: Wikipedia

List of Tellurium Compounds 

Tellurium’s chemical behavior resembles the one of sulfur and selenium in many aspects. Like these two chemical elements, tellurium also exhibits bi-, quadri-, and sexavalency. The tellurium compounds in a quadrivalent condition are the most stable compounds of this chemical element. 

In addition, tellurium typically adopts the oxidation states of −2, +2, +4, and +6 in a compound, and often forms oxocompounds, polytellurides, tellurides, and organotellurium compounds. ELement 52 also reacts with halogens (fluorine, chlorine, bromine, and iodine) to form halides.

Tellurides are a class of organotellurium compounds in which the main participant is tellurium. Most of them occur as natural chemical complexes:


  • Potassium tellurite
  • Sodium tellurite
  • Antimony telluride
  • Beryllium telluride
  • Bismuth telluride
  • Cadmium telluride
  • Cadmium zinc telluride
  • Chromium(III) telluride
  • Dimethyl telluride
  • Gallium(II) telluride
  • Gallium(III) telluride
  • Germanium telluride
  • Gold chalcogenides
  • Hydrogen telluride
  • Indium(III) telluride
  • Lead telluride
  • Lead tin telluride
  • Telluric acid
  • Manganese(II) telluride
  • Mercury cadmium telluride
  • Mercury telluride
  • Mercury zinc telluride
  • Molybdenum ditelluride
  • Potassium telluride
  • Rhenium ditelluride
  • Rubidium telluride
  • Silver telluride
  • Sodium telluride
  • Tantalum telluride
  • Telluride bromide
  • Telluride iodide
  • Telluride oxide
  • Telluride phosphide
  • Thallium(I) telluride
  • Tin telluride
  • Tungsten ditelluride
  • Tellurium iodide
  • Tellurium tetrabromide
  • Tellurium tetrachloride
  • Tellurium tetrafluoride
  • Tellurium tetraiodide
  • Dimethyl telluride
  • Diphenyl ditelluride
  • Tellurocysteine
  • Telluroketone
  • Tellurol

5 Interesting Facts and Explanations

  1. Tellurium is present in Earth’s crust only in about 0.001 parts per million.
  2. The name of the chalcogens comes from the Greek word ‘chalkos’, referring to the bronze ore. This group (16) in the periodic table includes the elements oxygen, tellurium, sulfur, selenium, and polonium
  3. Sylvanite and calverite are, in fact, tellurides of gold.
  4. For his discovery of tellurium, the Emperor Joseph II of Austria appointed Franz-Joseph Müller as the chief inspector of mines in Transylvania. After a while, he conferred upon him the title of Baron von Reichenstein. 
  5. The Hungarian chemist and botanist Pal Kitaibel independently discovered tellurium in 1789. 

Chemical Property and physical property of element Tellurium
Symbol of Tellurium: Te
Name: Tellurium
Atomic Number of Tellurium: 52
Group of Tellurium: Non-Metal
Crystal Structure of Tellurium: Hexagonal
Atomic Weight of Tellurium: 127.6
Shells of Tellurium: 2,8,18,18,6
Orbitals of Tellurium: [Kr] 4d10 5s2 5p4
Valence of Tellurium: 2,4,6
Melting Point of Tellurium:
Boiling Point of Tellurium:
Electro Negativity of Tellurium: 2.1
Covalent Radius of Tellurium: 1.36 Å
Ionic Radius of Tellurium: .97 (+4) Å
Atomic Radius of Tellurium: 1.42 Å
Atomic Volume of Tellurium: 20.5 cm³/mol
Name Origin of Tellurium: Latin: tellus (earth).
Discovered of Tellurium By: Franz Müller von Reichenstein
Year: 1782
Location: Romania
Pronounced of Tellurium: te-LOOR-i-em
Oxydation States of Tellurium: -2,(4),6
Density of Tellurium: 6.24 g/cm³
Uses of Tellurium: Used to improve the machining quality of copper and stainless steel products and to color glass and ceramics. Also in thermoelectric devices. Some is used in the rubber industry and it is a basic ingredient in manufacturing blasting caps.
Description of Tellurium: Shiny, black, non-metalic solid; as a gas it is violet and intensely irritating to the eyes, nose and throat.