Tellurium Te (Element 52) of Periodic Table

52 Te (Tellurium)

Tellurium is a semimetallic, crystalline, silver-white element. It exhibits metallic luster in pure form.
It is brittle, so it can easily pulverized.
A It forms many compounds corresponding to those of selenium and sulfur.
A Tellurium burned in air with a greenish-blue flame and forms tellurium dioxide (TeO₂),
Amorphous tellurium is found by precipitating tellurium from a solution of telluric or tellurous acid (H₂TeO₃).
Tellurium is a p-type semiconductor, and its conductivity increases slightly with exposure to light.

Tellurium element — UltraPure Tellurium Crystal

Tellurium powder amorphous — Tellurium Powder (Amorphous)

Identity
CAS Number: CAS13494-80-9
CID Number: CID6327182
DOT Hazard Class: 6.1
DOT Number: 2811
RTECS Number: RTECSWY2625000

CONTENT INDEX

Basic Properties of Tellurium

Pronunciation: Ta-lewr-ee-am
Appearance: Silver lustrous gray (crystalline) & Brown-black powder (amorphous)
Mass Number: 128
Standard Atomic weight: 127.60 g/mol
Atomic number (Z): 52
Electrons: 52
Protons: 52
Neutrons: 76
Period: 5
Group: 16
Block: p
Element category: Metalloid (semi metal)
Electrons per shell: K2, L8, M18, N18, O6
Electron configuration: 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d¹⁰5s²5p⁴

Tellurium electron configuration — Tellurium Electron Configuration

Thermal Properties of Tellurium

Phase: Solid
Melting point: 722.66 K (449.51 ^oC, 841.12 ^oF)
Boiling point: 1261 K (988 ^oC, 1810 ^oF)
Fusion heat: 17.49 kJ/mol
Vaporization heat: 114.1 kJ/mol
Specific heat: 201 J/(kg K)
Molar heat capacity: 25.73 J/(mol.K)
Thermal expansion: 18 μm/(m∙K)
Thermal conductivity: 1.97-3.38 W/(m∙K)

Electrical properties of Tellurium

Electrical conductivity: 0.01×10⁶ S/m
A Electrical resistivity: 0.0001 Ω∙m
A Electrical type: SemiConductor (p-type)

Magnetic Properties of Tellurium

A Magnetic type: Diamagnetic
Magnetic susceptibility (x_mol): -39.5×10^-6 cm³/mol
Volume magnetic susceptibility: -0.0000243
Mass magnetic susceptibility: -3.9×10^-9 m³/kg
Molar magnetic susceptibility: -0.498×10^-9 m³/mol

Physical Properties of Tellurium

Density: 6.24 g/cm³ (In solid) 5.70 g/cm³ (In Liquid)
Molar volume: 0.00002045 m³/mol
Young’s modulus: 43 GPa
Shear modulus: 16 GPa
Mohs Hardness: 2.25
Bulk modulus: 65 GPa
Brinell hardness: 180-270 MPa
Refractive index: 1.000991
Sound Speed: 2610 m/s

Atomic Properties of Tellurium

Oxidation states: 6, 5, 4¸ 3, 2, 1, -1, -2
Valence Electrons: 5s² 5p⁴
Ion charge: Te^2-
Ionization energies: 1st: 869.3 kJ.mol 2nd: 1790 kJ/mol 3rd: 2698 kJ/mol
Ionic radius: 97 pm
Atomic radius: 206 pm (Van der Waals)
Covalent radius: 138±4 pm
Filling Orbital: 5p⁴
Crystal structure: Hexagonal
Lattice angles: π/2, π/2, 2π/3
Lattice constant: 445.72, 445.72, 592.9 pm
Grid parameters: a=4.457 Å c=5.929 Å
Attitude c/a: 1.330
Space Group Name: P3₁21
Space Group Number: 152

Reactivity of Tellurium

Electronegativity: pauling scale: 2.1
Valence: +6
Electron affinity: 190.2 kJ/mol

Nuclear Properties of Tellurium

Half Life: Stable (Infinity)
Lifetime: Stable (Infinity)
Quantum Number: ³P₂
Neutron cross section (Brans): 5.4
Neutron Mass Absorption: 0.0013
Isotopes: 120_Te 121_Te 122_Te 123_Te 124_Te 125_Te 126_Te 127_Te 128_Te 129_Te 130_Te

Isotope	Abundance (%)	Atomic Mass g/mol	Half Life (t_1/2)
120_Te	0.09	119.904	Stable
121_Te	Syn	–	16.78 d
122_Te	2.55	121.903	Stable
123_Te	0.89	122.904	Stable
124_Te	4.74	123.903	Stable
125_Te	7.07	124.904	Stable
126_Te	18.84	125.903	Stable
127_Te	Syn	–	9.35 h
128_Te	31.74	127.904	2.2×10²⁴ y
129_Te	Syn	–	69.6 min
130_Te	34.08	129.906	7.9×10²⁰ y

Chemical Reactions

Tellurium is uneffected by water or hydrochloric acid, but dissolves in nitric acid.

The metal burns in air to form tellurium (IV) oxide:
Te (s) + 2 O₂ (g) → TeO₂ (s)

The metal reacts with Fluorine:
Te₈ (s) + 24 F₂ (g) → 8 TeF₆ (l) (tellurium (VI) fluoride)
Reacts with fluorine in nitrogen atmoshphere at 0 ^oC)
Te₈ (s) + 16 F₂ (g) → 8 TeF₄ (s) (tellurium (IV) fluoride)
React with other halogens in Nitrogen atmosphere at 0 ^oC to form tetra halides:
Te₈ (s) + 16 Cl₂ (g) → 8 TeCl₄ (s)
Te₈ (s) + 16 Br₂ (g) → 8 TeBr₄ (s)
Te₈ (s) + 24 I₂ (g) → 8 TeI₄ (s)

Production
The first step usually involves an oxidation in the presence of sodium carbonate (soda ash).
M₂Te + O₂ + Na₂CO₃ → Na₂TeO₃ + 2M + CO₂ (M= Cu, Ag, Au)
Put Cu in place of M in above reaction:
Cu₂Te + Na₂CO₃ + O₂ → 2 Cu + Na₂TeO₃ + CO₂
OR
Cu₂Te + Na₂CO₃ + 2 O₂ → 2 CuO + Na₂TeO₃ + CO₂
The Tellurite (Na₂TeO₃) is separated by sulphuric acid (H₂SO₄) and tellurium precipitates out as the dioxide. Tellurium is liberated from the dioxide by dissolving in sodium hydroxide, NaOH, and electroytic reduction.
TeO₂ + 2 NaOH → Na₂TeO₃ + H₂O → Te + 2 NaOH + O₂

Tellurium History

Naming: After Roman Tellus, deity of the earth
Discovery: Franz-Joseph Muller von Reichenstein (1782)
First isolation: Martin Heinrich Klaproth

Tellurium Uses

Tellurium is used in alloys, mostly with aluminium, tin, copper and stainless steel, to improve their machinability. It is added to lead to improve its strength and hardness and makes corrosive resistant to sulphuric acid on lead.
Tellurium has been used as a basic ingredient in blasting caps, to vulcanize rubber, to tint glass and ceramics, in solar cells, in rewritable CDs and DVDs,as a catalyst in oil refining, and is added to cast iron for chill control.
A Tellurium can be doped with gold, silver, copper or tin in semiconductor applications.

Bismuth telluride has been used in thermoelectric devices.

Biological role: It is very toxic and teratogenic (it is an agent that can disturbs the development of an embryo or foetus).

Abundance of Tellurium

Tellurium is occasionally found in minerals calaverite, sylvanite and tellurite, but more often found in the telluride.
It is obtained commercially from anode sludges produced during the electrolytic refining of blister copper.
Obtain 1 Kg (2.2 Pounds) of tellurium by treatment of 1000 tons of copper ore.

Annual world wide production is around 215 tons.
9×10^-7% (In Universe)
21×10^-5% (In Meteorites)
1×10^-7% (In Earth’s Crust)