Te 52

Tellurium (Te)

metalloid

Period: 5 Group: 16 Block: p

Solid

Standard Atomic Weight

Electron configuration

[Kr] 5s² 4d¹⁰ 5p⁴

Melting point

449.51 °C (722.66 K)

Boiling point

987.85 °C (1261 K)

Density

6232 kg/m³

Oxidation states

−2, −1, 0, +1, +2, +3, +4, +5, +6

Electronegativity (Pauling)

2.1

Ionization energy (1st)

Discovery year

1782

Atomic radius

140 pm

Details

Name origin Latin: tellus (earth).

Discovery country Romania

Discoverers Franz Müller von Reichenstein

Tellurium is a brittle metalloid in group 16, below selenium and above polonium. It is chemically related to sulfur and selenium but is more metallic, less abundant, and more easily reduced. In nature it occurs mainly as telluride minerals and as a minor constituent of copper ores. Its technological importance comes from semiconducting and thermoelectric compounds, cadmium telluride photovoltaics, and small alloying additions that modify machinability and corrosion behavior.

Crystalline tellurium has a silvery-white appearance, and when pure it exhibits a metallic luster. It is brittle and easily pulverized. Amorphous tellurium is found by precipitating tellurium from a solution of telluric or tellurous acid. Whether this form is truly amorphous, or made of minute crystals, is open to question. Tellurium is a p-type semiconductor, and shows greater conductivity in certain directions, depending on alignment of the atoms.

Its conductivity increases slightly with exposure to light. It can be doped with silver, copper, gold, tin, or other elements. In air, tellurium burns with a greenish-blue flames, forming the dioxide. Molten tellurium corrodes iron, copper, and stainless steel.

The name derives from the Latin Tellus, who was the Roman goddess of the Earth. Tellurium was discovered by Franz Joseph Müller von Reichenstein in 1782 and overlooked for 15 years until it was isolated by the German chemist Martin-Heinrich Klaproth in 1798. The Hungarian chemist Paul Kitaibel independently discovered tellurium in 1789, prior to Klaproth's work but after von Reichenstein.

Tellurium was discovered by Franz Joseph Müller von Reichenstein, a Romanian mining official, in 1782. Reichenstein was the chief inspector of all mines, smelters and saltworks in Transylvania. He also had an interest in chemistry and extracted a new metal from an ore of gold, known as aurum album, which he believed was antimony. He shortly realized that the metal he had produced wasn't antimony at all, but a previously unknown element. Reichenstein's work was forgotten until 1798 when Martin Heinrich Klaproth, a German chemist, mentioned the substance in a paper. Klaproth named the new element tellurium but gave full credit for its discovery to Reichenstein. Tellurium is found free in nature, but is most often found in the ores sylvanite (AgAuTe4), calaverite (AuTe2) and krennerite (AuTe2). Today, most tellurium is obtained as a byproduct of mining and refining copper.

From the Latin word tellus, earth. Discovered by Muller von Reichenstein in 1782; named by Klaproth, who isolated it in 1798.

Read about Tellurium on Wikipedia

Images

Properties

Physical

Atomic radius (empirical) 140 pm

Covalent radius 138 pm

Van der Waals radius 206 pm

Metallic radius 137 pm

Density

Molar volume 0.0205 L/mol

Phase at STP solid

Melting point 449.51 °C

Boiling point 987.85 °C

Thermal conductivity 14.3 W/(m·K)

Specific heat capacity 0.202 J/(g·K)

Molar heat capacity 25.73 J/(mol·K)

Crystal structure hcp

Chemical

Electronegativity (Pauling) 2.1

Electronegativity (Allen) 2.158

Electron affinity

Ionization energy (1st)

Ionization energy (2nd)

Ionization energy (3rd)

Ionization energy (4th)

Ionization energy (5th)

Oxidation states −2, −1, 0, +1, +2, +3, +4, +5, +6

Valence electrons 6

Electron configuration

Electron configuration (semantic)

Thermodynamic

Critical point (temperature) 2056 °C

Heat of fusion 0.1812717 eV

Heat of vaporization 0.54412603 eV

Heat of sublimation 2.041768 eV

Heat of atomization 2.041768 eV

Atomization enthalpy

Nuclear

Stable isotopes 5

Discovery year 1782

Abundance

Abundance (Earth's crust) 0.001 mg/kg

Reactivity

N/A

Crystal Structure

Lattice constant a 445 pm

Electronic Structure

Electrons per shell 2, 8, 18, 18, 6

Identifiers

CAS number 13494-80-9

Term symbol

InChI InChI=1S/Te

InChI Key PORWMNRCUJJQNO-UHFFFAOYSA-N

Electron Configuration Measured

Ion charge

Protons 52

Electrons 52

Charge Neutral

Configuration Te: 4d¹⁰ 5s² 5p⁴

[Kr] 4d¹⁰ 5s² 5p⁴

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁴

Orbital diagram

↑↓

2/2

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑↓

10/10

↑↓

6/6

↑↓

2/2

↑↓

10/10

↑↓

↑

4/6 2↑

Total electrons: 52 Unpaired: 2

Atomic model

Protons 52

Neutrons 74

Electrons 52

Mass number 126

Stability Stable

Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.

Schematic atomic model, not to scale.

Atomic Fingerprint

Emission / Absorption Spectrum

Emission Visible: 380–750 nm

Isotope Distribution

Mass number	Atomic mass (u)	Natural abundance	Half-life
122 Stable	121.9030435 ± 0.0000016	2.5500%	Stable
124 Stable	123.9028171 ± 0.0000016	4.7400%	Stable
125 Stable	124.9044299 ± 0.0000016	7.0700%	Stable
126 Stable	125.9033109 ± 0.0000016	18.8400%	Stable

Measured

Phase / State

Solid 25 °C (298.15 K)

Reason: 424.5 °C below melting point (449.51 °C)

Melting point 449.51 °C

Boiling point 987.85 °C

Below melting by 424.5 °C

0 K Current temperature: 25 °C 6000 K

Phase timeline

Schematic, not to scale

Solid

Liquid

Gas

Melting

Boiling

25°C

Solid

Liquid

Gas

Current

Phase transition points

Melting point Literature

449.51 °C

Boiling point Literature

987.85 °C

Current phase Calculated
Solid

Transition energies

Heat of fusion Literature

0.1812717 eV

Energy required to melt 1 mol at melting point

Heat of vaporization Literature

0.54412603 eV

Energy required to vaporize 1 mol at boiling point

Heat of sublimation Literature

2.041768 eV

Energy required to sublime 1 mol at sublimation point

Density

Reference density Literature

6232 kg/m³

At standard conditions

Current density Calculated

6232 kg/m³

At standard conditions

Advanced

Critical point Literature

2056 °C

Atomic Spectra

Showing 10 of 52 Atomic Spectra. Sorted by ion charge (ascending).

Lines Holdings ?

Ion	Charge	Total lines	Transition probabilities	Level designations
Te I	0	133	6	112
Te II	+1	345	0	310

NIST Lines Holdings →

Levels Holdings ?

Ion	Charge	Levels
Te I	0	120
Te II	+1	129
Te III	+2	55
Te IV	+3	16
Te V	+4	45
Te VI	+5	9
Te VII	+6	60
Te VIII	+7	2
Te IX	+8	2
Te X	+9	2

NIST Levels Holdings →

52 Te 127.6

Tellurium — Atomic Orbital Visualizer

[Kr]5s24d105p4

Energy levels 2 8 18 18 6

Oxidation states -2, -1, 0, +1, +2, +3, +4, +5, +6

HOMO 5p n=5 · l=1 · m=-1

Tellurium — Atomic Orbital Visualizer Preview

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52 Te 127.6

Tellurium — Crystal Structure Visualizer

Primitive Hexagonal · Pearson hP2

Experimental

Pearson hP2

Coord. № 12

Packing 74.048%

Tellurium — Crystal Structure Visualizer Preview

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Ionic Radii

Charge	Coordination	Spin	Radius
-2	6	N/A	221 pm
+4	3	N/A	52 pm
+4	4	N/A	66 pm
+4	6	N/A	97 pm
+6	4	N/A	43 pm
+6	6	N/A	56.00000000000001 pm

Compounds

127.600 u

Te+4

127.600 u

131.909 u

124.904 u

132.911 u

125.903 u

129.906 u

128.907 u

126.905 u

122.904 u

130.909 u

120.905 u

121.903 u

127.904 u

115.909 u

133.911 u

Te+

127.600 u

Te+4

124.904 u

123.903 u

109.922 u

119.904 u

Isotopes (4)

Thirty isotopes of tellurium are known, with atomic masses ranging from 108 to 137. Natural tellurium consists of eight isotopes.

Mass number	Atomic mass (u)	Natural abundance	Half-life	Decay mode
122 Stable	121.9030435 ± 0.0000016	2.5500% ± 0.1200%	Stable	stable
124 Stable	123.9028171 ± 0.0000016	4.7400% ± 0.1400%	Stable	stable
125 Stable	124.9044299 ± 0.0000016	7.0700% ± 0.1500%	Stable	stable
126 Stable	125.9033109 ± 0.0000016	18.8400% ± 0.2500%	Stable	stable

122 Stable

Atomic mass (u) 121.9030435 ± 0.0000016

Natural abundance 2.5500% ± 0.1200%

Half-life Stable

Decay mode

stable

124 Stable

Atomic mass (u) 123.9028171 ± 0.0000016

Natural abundance 4.7400% ± 0.1400%

Half-life Stable

Decay mode

stable

125 Stable

Atomic mass (u) 124.9044299 ± 0.0000016

Natural abundance 7.0700% ± 0.1500%

Half-life Stable

Decay mode

stable

126 Stable

Atomic mass (u) 125.9033109 ± 0.0000016

Natural abundance 18.8400% ± 0.2500%

Half-life Stable

Decay mode

stable

Spectral Lines

Showing 50 of 74 Spectral Lines. Only spectral lines with measured intensity are shown by default.

Wavelength (nm)	Intensity	Ion stage	Type	Transition	Accuracy	Source
486.623 nm	2300	Te II	emission	5s2.5p2.(3P).6p 4D* → 5s2.5p2.(3P).6d 4F	Measured	NIST
557.636 nm	2100	Te II	emission	5s2.5p2.(1D).6s 2D → 5s2.5p2.(1D).6p 2F*	Measured	NIST
570.812 nm	1900	Te II	emission	5s2.5p2.(3P).6s 4P → 5s2.5p2.(3P).6p 4D*	Measured	NIST
483.13 nm	1600	Te II	emission	5s2.5p2.(3P).6p 4D* → 5s2.5p2.(3P).6d 4P	Measured	NIST
564.926 nm	1500	Te II	emission	5s2.5p2.(3P).6s 4P → 5s2.5p2.(3P).6p 4D*	Measured	NIST
575.586 nm	1500	Te II	emission	5s2.5p2.(3P).6s 4P → 5s2.5p2.(3P).6p 4D*	Measured	NIST
544.984 nm	1400	Te II	emission	5s2.5p2.(3P).6s 4P → 5s2.5p2.(3P).6p 4P*	Measured	NIST
468.691 nm	1310	Te II	emission	5s2.5p2.(3P).6p 4P* → 5s2.5p2.(3P).6d 4D	Measured	NIST
476.605 nm	1300	Te II	emission	5s2.5p2.(3P).6p 2D* → 5s2.5p2.(3P).6d 2F	Measured	NIST
490.442 nm	1300	Te II	emission	5s2.5p2.(3P).6p 2D* → 5s2.5p2.(3P).6d 2F	Measured	NIST
566.622 nm	1200	Te II	emission	5s2.5p2.(3P).6s 2P → 5s2.5p2.(3P).6p 2D*	Measured	NIST
597.468 nm	1200	Te II	emission	5s2.5p2.(3P).6s 4P → 5s2.5p2.(3P).6p 4P*	Measured	NIST
548.795 nm	1100	Te II	emission	5s2.5p2.(3P).5d 2P → 5s2.5p2.(3P).6p 4D*	Measured	NIST
484.29 nm	1000	Te II	emission	5s2.5p2.(3P).5d 2D → 5s2.5p2.(3P).4f 4D*	Measured	NIST
486.513 nm	1000	Te II	emission	5s2.5p2.(3P).6p 4D* → 5s2.5p2.(3P).6d 4D	Measured	NIST
482.712 nm	900	Te II	emission	5s2.5p2.(3P).6p 4P* → 5s2.5p2.(3P).6d 4D	Measured	NIST
447.865 nm	830	Te II	emission	5s2.5p2.(3P).6p 4P* → 5s2.5p2.(3P).6d 4D	Measured	NIST
500.081 nm	810	Te II	emission	5s2.5p2.(3P).6s 4P → 5s2.5p2.(3P).6p 2D*	Measured	NIST
477.155 nm	800	Te II	emission	5s2.5p2.(3P).6p 4D* → 5s2.5p2.(3P).6d 4F	Measured	NIST
593.615 nm	730	Te II	emission	5s2.5p2.(3P).6s 4P → 5s2.5p2.(3P).6p 4S*	Measured	NIST
464.111 nm	680	Te II	emission	5s2.5p2.(3P).6p 4D* → 5s2.5p2.(3P).6d 4D	Measured	NIST
470.654 nm	670	Te II	emission	5s2.5p2.(1D).6s 2D → 5s2.5p2.(1D).6p 2P*	Measured	NIST
436.402 nm	650	Te II	emission	5s2.5p2.(3P).5d 4P → 5s2.5p2.(3P).4f 4D*	Measured	NIST
636.713 nm	570	Te II	emission	5s.(2S).5p4.(1D) 2D → 5s2.5p2.(3P).6p 4D*	Measured	NIST
469.638 nm	560	Te II	emission	5s2.5p2.(3P).5d 4P → 5s2.5p2.(3P).4f 2D*	Measured	NIST
416.977 nm	540	Te II	emission	5s2.5p2.(3P).5d 2D → 5s2.5p2.(3P).4f 2F*	Measured	NIST
463.062 nm	540	Te II	emission	5s2.5p2.(3P).6p 4S* → 5s2.5p2.(3P).7s 2P	Measured	NIST
478.488 nm	510	Te II	emission	5s2.5p2.(1D).6s 2D → 5s2.5p2.(1D).6p 2P*	Measured	NIST
455.778 nm	480	Te II	emission	5s2.5p2.(3P).6p 4S* → 5s2.5p2.(3P).6d 4D	Measured	NIST
683.7663 nm	430	Te I	emission	5p3.(4S).6p 5P → 5p3.(4S).8d 5D*	Measured	NIST
404.716 nm	400	Te II	emission	5s2.5p2.(3P).5d 4P → 5s2.5p2.(3P).4f 2D*	Measured	NIST
428.583 nm	370	Te II	emission	5s2.5p2.(3P).6p 2S* → 5s2.5p2.(3P).6d 4D	Measured	NIST
394.798 nm	340	Te II	emission	5s2.5p2.(3P).5d 4P → 5s2.5p2.(3P).4f 4F*	Measured	NIST
422.572 nm	340	Te II	emission	5s2.5p2.(3P).5d 4P → 5s2.5p2.(3P).4f 4D*	Measured	NIST
396.921 nm	320	Te II	emission	5s.(2S).5p4.(1D) 2D → 5s2.5p2.(1D).6p 2D*	Measured	NIST
410.105 nm	320	Te II	emission	5s2.5p2.(1D).5d 2S → 5s2.5p2.(3P).4f 2D*	Measured	NIST
412.732 nm	320	Te II	emission	5s2.5p2.(1D).5d 2S → 5s2.5p2.(3P).4f 4D*	Measured	NIST
496.187 nm	320	Te II	emission	5s2.5p2.(3P).6p 4P* → 5s2.5p2.(3P).6d 4D	Measured	NIST
400.653 nm	310	Te II	emission	5s.(2S).5p4.(3P) 4P → 5s2.5p2.(3P).6p 4D*	Measured	NIST
438.51 nm	310	Te II	emission	5s2.5p2.(3P).5d 4P → 5s2.5p2.(3P).4f 2D*	Measured	NIST
417.929 nm	300	Te II	emission	5s2.5p2.(3P).5d 4P → 5s2.5p2.(1S).6p 2P*	Measured	NIST
427.343 nm	300	Te II	emission	5s2.5p2.(3P).6p 2S* → 5s2.5p2.(3P).7s 2P	Measured	NIST
679.109 nm	300	Te I	emission	5p3.(4S).6p 5P → 5p3.(4S).8d 3D*	Measured	NIST
669.0154 nm	290	Te I	emission	5p3.(4S).6p 5P → 5p3.(4S).8d 5D*	Measured	NIST
453.708 nm	260	Te II	emission	5s2.5p2.(3P).5d 4P → 5s2.5p2.(3P).4f 4F*	Measured	NIST
397.592 nm	250	Te II	emission	5s.(2S).5p4.(1D) 2D → 5s2.5p2.(1D).6p 2F*	Measured	NIST
416.356 nm	250	Te II	emission	5s2.5p2.(3P).5d 4P → 5s2.5p2.(3P).4f 4D*	Measured	NIST
398.176 nm	240	Te II	emission	5s2.5p2.(3P).6s 2P → 5s2.5p2.(1D).6p 2P*	Measured	NIST
425.114 nm	240	Te II	emission	5s2.5p2.(3P).5d 2D → 5s2.5p2.(3P).4f 2F*	Measured	NIST
404.888 nm	230	Te II	emission	5s.(2S).5p4.(3P) 4P → 5s2.5p2.(3P).6p 4S*	Measured	NIST

Extended Properties

Covalent Radii (Extended)

Covalent radius (Pyykkö)

Covalent radius (Pyykkö, double)

Covalent radius (Pyykkö, triple)

Covalent radius (Bragg)

Van der Waals Radii

Bondi

Batsanov

Alvarez

UFF

MM3

Dreiding

Atomic & Metallic Radii

Atomic radius (Rahm)

Metallic radius (C12)

Numbering Scales

Mendeleev

Pettifor

Glawe

Electronegativity Scales

Ghosh

Gunnarsson–Lundqvist

Robles–Bartolotti

Polarizability & Dispersion

Dipole polarizability

Dipole polarizability (unc.)

C₆

C₆ (Gould–Bučko)

Phase Transitions & Allotropes

Melting point	722.66 K
Boiling point	1261.15 K
Critical point (temperature)	2329.15 K

Oxidation State Categories

+2 main

−2 main

+1 extended

+6 main

+3 extended

0 extended

+5 extended

−1 extended

+4 main

Advanced Reference Data

Screening Constants (11)

n	Orbital	σ
1	s	1.0432
2	p	4.14
2	s	13.6688
3	d	14.1607
3	p	17.9911
3	s	18.0019
4	d	32.04
4	p	28.878
4	s	27.5916
5	p	41.1915

Crystal Radii Detail (6)

Charge	CN	r_crystal (pm)	Origin
-2	VI	207	Pauling's (1960) crystal radius,
4	III	66
4	IV	80
4	VI	111
6	IV	57	calculated,
6	VI	70

Isotope Decay Modes (67)

Isotope	Mode	Intensity
104	A	100%
105	A	100%
106	A	100%
107	A	70%
107	B+	—
107	B+p	—
108	B+	51%
108	A	49%
108	B+p	2.4%
108	B+A	0.1%

X‑ray Scattering Factors (508)

Energy (eV)	f₁	f₂
10	—	9.70237
10.1617	—	9.72653
10.3261	—	9.75076
10.4931	—	9.77506
10.6628	—	9.7994
10.8353	—	9.77638
11.0106	—	9.72308
11.1886	—	9.67008
11.3696	—	9.61736
11.5535	—	9.54395

Additional Data

Estimated Crustal Abundance

The estimated element abundance in the earth's crust.

1×10-3 milligrams per kilogram

References (1)

[5] Tellurium https://education.jlab.org/itselemental/ele052.html

Estimated Oceanic Abundance

The estimated element abundance in the earth's oceans.

Not Applicable

References (1)

[5] Tellurium https://education.jlab.org/itselemental/ele052.html

Sources

Sources of this element.

Tellurium is occasionally found native, but is more often found as the telluride of gold (calaverite), and combined with other metals. It is recovered commercially from anode muds produced during the electrolytic refining of blister copper. The U.S., Canada, Peru, and Japan are the largest Free World producers of the element.

References (1)

[6] Tellurium https://periodic.lanl.gov/52.shtml

References

(9)

1 PubChem

Data deposited in or computed by PubChem

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2 Atomic Mass Data Center (AMDC), International Atomic Energy Agency (IAEA)

The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.

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3 IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW)

Tellurium

Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.

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4 IUPAC Periodic Table of the Elements and Isotopes (IPTEI)

The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.

Visit source License

License note: Copyright (c) 2020 International Union of Pure and Applied Chemistry. The International Union of Pure and Applied Chemistry (IUPAC) contribution within Pubchem is provided under a CC-BY-NC-ND 4.0 license, unless otherwise stated.

5 Jefferson Lab, U.S. Department of Energy

Tellurium

Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/

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License note: Please see citation and linking information: https://education.jlab.org/faq/index.html

6 Los Alamos National Laboratory, U.S. Department of Energy

Tellurium

The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.

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7 NIST Physical Measurement Laboratory

Tellurium

The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database

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8 PubChem Elements

Tellurium

This section provides all form of data related to element Tellurium.

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9 PubChem Elements

Tellurium

The element property data was retrieved from publications.

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Last updated: May 1, 2026

Data verified: May 12, 2026

Content is reviewed against latest scientific data.