Difference between revisions of "Tellurium"

From Sciencemadness Wiki
Jump to: navigation, search
(Added element infobox.)
(Fixed a mistake in my edit.)
 
(8 intermediate revisions by 3 users not shown)
Line 22: Line 22:
 
brown-black powder (amorphous)
 
brown-black powder (amorphous)
 
<!-- Periodic table -->
 
<!-- Periodic table -->
|above=selenium
+
|above=[[Selenium|Se]]
|below=polonium
+
|below=[[Polonium|Po]]
|left=antimony
+
|left=[[Antimony]]
|right=iodine
+
|right=[[Iodine]]
 
|number=52
 
|number=52
 
|atomic mass=127.6
 
|atomic mass=127.6
Line 31: Line 31:
 
|atomic mass ref=
 
|atomic mass ref=
 
|atomic mass comment=
 
|atomic mass comment=
|series=
+
|series=Chalcogens
 
|series ref=
 
|series ref=
|series comment=
+
|series comment=Chalcogens
 
|series color=
 
|series color=
 
|group=16
 
|group=16
 
|group ref=
 
|group ref=
|group comment=
+
|group comment=16
 
|period=4
 
|period=4
 
|period ref=
 
|period ref=
 
|period comment=
 
|period comment=
|block=
+
|block=p
 
|block ref=
 
|block ref=
 
|block comment=
 
|block comment=
Line 57: Line 57:
 
|phase comment=
 
|phase comment=
 
|melting point K=722.66
 
|melting point K=722.66
|melting point C=
+
|melting point C=449.51
|melting point F=
+
|melting point F=​841.12
 
|melting point ref=
 
|melting point ref=
 
|melting point comment=
 
|melting point comment=
 
|boiling point K=1261
 
|boiling point K=1261
|boiling point C=
+
|boiling point C=988
|boiling point F=
+
|boiling point F=1810
 
|boiling point ref=
 
|boiling point ref=
 
|boiling point comment=
 
|boiling point comment=
Line 105: Line 105:
 
|critical point ref=
 
|critical point ref=
 
|critical point comment=
 
|critical point comment=
|heat fusion=17.49 kJ/mol
+
|heat fusion=17.49
 
|heat fusion ref=
 
|heat fusion ref=
 
|heat fusion comment=
 
|heat fusion comment=
Line 111: Line 111:
 
|heat fusion 2 ref=
 
|heat fusion 2 ref=
 
|heat fusion 2 comment=
 
|heat fusion 2 comment=
|heat vaporization=114.1 kJ/mol
+
|heat vaporization=114.1
 
|heat vaporization ref=
 
|heat vaporization ref=
 
|heat vaporization comment=
 
|heat vaporization comment=
|heat capacity=25.73 J/(mol·K)
+
|heat capacity=25.73
 
|heat capacity ref=
 
|heat capacity ref=
 
|heat capacity comment=
 
|heat capacity comment=
Line 144: Line 144:
 
|electronegativity ref=
 
|electronegativity ref=
 
|electronegativity comment=
 
|electronegativity comment=
|ionization energy 1=869.3 kJ/mol
+
|ionization energy 1=869.3
 
|ionization energy 1 ref=
 
|ionization energy 1 ref=
 
|ionization energy 1 comment=
 
|ionization energy 1 comment=
|ionization energy 2=1790 kJ/mol
+
|ionization energy 2=1790
 
|ionization energy 2 ref=
 
|ionization energy 2 ref=
 
|ionization energy 2 comment=
 
|ionization energy 2 comment=
|ionization energy 3=2698 kJ/mol
+
|ionization energy 3=2698
 
|ionization energy 3 ref=
 
|ionization energy 3 ref=
 
|ionization energy 3 comment=
 
|ionization energy 3 comment=
Line 156: Line 156:
 
|ionization energy ref=
 
|ionization energy ref=
 
|ionization energy comment=
 
|ionization energy comment=
|atomic radius=140 pm
+
|atomic radius=140
 
|atomic radius ref=
 
|atomic radius ref=
 
|atomic radius comment=
 
|atomic radius comment=
Line 162: Line 162:
 
|atomic radius calculated ref=
 
|atomic radius calculated ref=
 
|atomic radius calculated comment=
 
|atomic radius calculated comment=
|covalent radius=138±4 pm
+
|covalent radius=138±4
 
|covalent radius ref=
 
|covalent radius ref=
 
|covalent radius comment=
 
|covalent radius comment=
|Van der Waals radius=206 pm
+
|Van der Waals radius=206  
 
|Van der Waals radius ref=
 
|Van der Waals radius ref=
 
|Van der Waals radius comment=
 
|Van der Waals radius comment=
Line 180: Line 180:
 
|speed of sound ref=
 
|speed of sound ref=
 
|speed of sound comment=
 
|speed of sound comment=
|speed of sound rod at 20=2610 m/s
+
|speed of sound rod at 20=2610
 
|speed of sound rod at 20 ref=
 
|speed of sound rod at 20 ref=
 
|speed of sound rod at 20 comment=
 
|speed of sound rod at 20 comment=
Line 186: Line 186:
 
|speed of sound rod at r.t. ref=
 
|speed of sound rod at r.t. ref=
 
|speed of sound rod at r.t. comment=
 
|speed of sound rod at r.t. comment=
|thermal expansion=18 µm/(m·K)
+
|thermal expansion=18  
 
|thermal expansion ref=
 
|thermal expansion ref=
 
|thermal expansion comment=
 
|thermal expansion comment=
Line 192: Line 192:
 
|thermal expansion at 25 ref=
 
|thermal expansion at 25 ref=
 
|thermal expansion at 25 comment=
 
|thermal expansion at 25 comment=
|thermal conductivity=1.97–3.38 W/(m·K)
+
|thermal conductivity=1.97–3.38
 
|thermal conductivity ref=
 
|thermal conductivity ref=
 
|thermal conductivity comment=
 
|thermal conductivity comment=
Line 223: Line 223:
 
|tensile strength ref=
 
|tensile strength ref=
 
|tensile strength comment=
 
|tensile strength comment=
|Young's modulus=
+
|Young's modulus=43
 
|Young's modulus ref=
 
|Young's modulus ref=
 
|Young's modulus comment=
 
|Young's modulus comment=
|Shear modulus=
+
|Shear modulus=16
 
|Shear modulus ref=
 
|Shear modulus ref=
 
|Shear modulus comment=
 
|Shear modulus comment=
|Bulk modulus=
+
|Bulk modulus=65
 
|Bulk modulus ref=
 
|Bulk modulus ref=
 
|Bulk modulus comment=
 
|Bulk modulus comment=
Line 244: Line 244:
 
|Vickers hardness ref=
 
|Vickers hardness ref=
 
|Vickers hardness comment=
 
|Vickers hardness comment=
|Brinell hardness=180–270 MPa
+
|Brinell hardness=180–270
 
|Brinell hardness ref=
 
|Brinell hardness ref=
 
|Brinell hardness comment=
 
|Brinell hardness comment=
Line 268: Line 268:
 
|history comment=
 
|history comment=
 
<!-- Isotopes -->
 
<!-- Isotopes -->
|isotopes=120Te, 122Te, 123Te, 124Te, 125Te, 126Te, 128Te, 130Te
+
|isotopes=
 
|isotopes comment=
 
|isotopes comment=
 
|engvar=
 
|engvar=
  }}'''Tellurium''' is the element with symbol '''Te''' and atomic number 52.
+
  }}
 +
'''Tellurium''' is the element with symbol '''Te''' and atomic number 52.
 +
 
 
==Properties==
 
==Properties==
 
=== Chemical ===
 
=== Chemical ===
It is usually found in '''-2''', '''+2''', '''+4''' and '''+6''' oxidation states. It has chemical properties similar to selenium, being dissolved by sulphuric and nitric acid and potassium hydroxide solutions but not in water. It corrodes copper, iron and stainless steel when it's molten. It reacts with oxygen in air, hydrogen and with halogens. It burns with a blueish grey flame. Although being mildly toxic, it is infamous for making you smell really bad so don´t handle it without correct safety equipment.
+
It is usually found in '''-2''', '''+2''', '''+4''' and '''+6''' oxidation states. It has chemical properties similar to [[selenium]], being dissolved by [[sulfuric acid|sulfuric]] and [[nitric acid]] and [[potassium hydroxide]] solutions but not in water. It corrodes copper, iron, and stainless steel in its molten state. It reacts with oxygen in air, hydrogen, and halogens. It burns with a blueish-grey flame. Although being mildly toxic, it is infamous for making you smell really bad so don´t handle it without correct safety equipment.
  
 
=== Physical ===
 
=== Physical ===
Tellurium is a whitish-silvery solid, crystalline element which has a nice, metallic luster. It's a brittle and easily powderized metalloid. It's a good semiconductor, and conductivity increases slightly when exposed to light. It melts at 450 ºC and boils at almost 1000 ºC.
+
Tellurium is a whitish-silvery solid, crystalline element that has a nice, metallic luster. It's a brittle and easily powdered metalloid. tellurium is a good semiconductor, and conductivity increases slightly when exposed to light. It melts at 450 ºC and boils at almost 1000 ºC.
  
 
== Availability ==
 
== Availability ==
 
Tellurium is one of the rarest stable elements on Earth's crust. Applications are scarce, most commonly used in electronics and solar panels. Prices are high and it has few uses for home chemists, in addition to collecting elements.
 
Tellurium is one of the rarest stable elements on Earth's crust. Applications are scarce, most commonly used in electronics and solar panels. Prices are high and it has few uses for home chemists, in addition to collecting elements.
 +
 +
Rewritable disks contain a small layer of tellurium oxide, though you will need dozens if not hundreds to isolate a significant amount of elemental tellurium.
 +
 +
Tellurium is sometimes found in its native (i.e., elemental) form, but is more often found as the tellurides of gold such as calaverite and krennerite (two different polymorphs of AuTe<sub>2</sub>), petzite, Ag<sub>3</sub>AuTe<sub>2</sub>, and sylvanite, AgAuTe<sub>4</sub>.
  
 
==Production==
 
==Production==
Tellurium can be prepared by reducing tellurium compounds.
+
Tellurium can be prepared by reducing tellurium compounds, like metal tellurides. The procedure is very hazardous, as hydrogen telluride may form during the process. Purchasing the free element may be cheaper.
 +
 
 +
Gold, silver, copper tellurides are roasted with [[sodium carbonate]] under air at temperatures of 500 °C. The metal ions are reduced to the metals, while the telluride is converted to sodium tellurite.
 +
 
 +
:M<sub>2</sub>Te + O<sub>2</sub> + Na<sub>2</sub>CO<sub>3</sub> → Na<sub>2</sub>TeO<sub>3</sub> + 2 M + CO<sub>2</sub>
 +
 
 +
Tellurites can be leached from the mixture with water and are normally present as hydrotellurites HTeO<sub>3</sub><sup>−</sup> in solution. Selenites may also be formed during this process if any selenides are present, but they can be separated by adding [[sulfuric acid]]. The hydrotellurites are converted into the insoluble [[tellurium dioxide]], while the selenites stay in solution.
 +
 
 +
: {{chem|HTeO|3|-}} + OH<sup>−</sup> + H<sub>2</sub>SO<sub>4</sub> → TeO<sub>2</sub> + {{chem|SO|4|2-}} + 2 H<sub>2</sub>O
 +
 
 +
Elemental tellurium is obtained by reducing the oxide either by electrolysis or by reacting the tellurium dioxide with [[sulfur dioxide]] in sulfuric acid.
 +
 
 +
: TeO<sub>2</sub> + 2 SO<sub>2</sub> + 2H<sub>2</sub>O → Te + 2 {{chem|SO|4|2-}} + 4 H<sup>+</sup>
 +
 
 +
The above procedure may not work on other tellurides, like cadmium telluride.
  
 
==Projects==
 
==Projects==
 
*Make tellurium dioxide
 
*Make tellurium dioxide
 
*Make sodium tellurite
 
*Make sodium tellurite
 +
*Element collecting
  
 
==Handling==
 
==Handling==
Line 299: Line 320:
  
 
===Disposal===
 
===Disposal===
It is best to try to recycle it.
+
Since tellurium is rare and expensive, it's best to try to recycle it.
  
 
==References==
 
==References==
Line 312: Line 333:
 
[[Category:Chalcogens]]
 
[[Category:Chalcogens]]
 
[[Category:P-block]]
 
[[Category:P-block]]
 +
[[Category:Minerals]]

Latest revision as of 19:15, 30 August 2020

Tellurium,  52Te
Tellurium2.jpg
Metallic tellurium, diameter 3.5 cm
General properties
Name, symbol Tellurium, Te
Appearance

silvery lustrous gray (crystalline),

brown-black powder (amorphous)
Tellurium in the periodic table
Se

Te

Po
AntimonyTelluriumIodine
Atomic number 52
Standard atomic weight (Ar) 127.6
Element category , Chalcogens
Group, block 16; p-block
Period period 4
Electron configuration [Kr] 4d10 5s2 5p4
per shell
2, 8, 18, 18, 6
Physical properties
silvery-gray
Phase solid
Melting point 722.66 K ​(449.51 °C, ​​841.12 °F)
Boiling point 1261 K ​(988 °C, ​1810 °F)
Density near r.t. 6.24 g/cm3
when liquid, at  5.70 g/cm3
Heat of fusion 17.49 kJ/mol
Heat of 114.1 kJ/mol
Molar heat capacity 25.73 J/(mol·K)
 pressure
Atomic properties
Oxidation states 6, 5, 4, 3, 2, 1, −1, −2 ​a mildly acidic oxide
Electronegativity Pauling scale: 2.1
energies 1st: 869.3 kJ/mol
2nd: 1790 kJ/mol
3rd: 2698 kJ/mol
Atomic radius empirical: 140 pm
Covalent radius 138±4 pm
Van der Waals radius 206 pm
Miscellanea
Crystal structure
Speed of sound thin rod 2610 m/s (at 20 °C)
Thermal expansion 18 µm/(m·K)
Thermal conductivity 1.97–3.38 W/(m·K)
Magnetic ordering diamagnetic
Young's modulus 43 GPa
Shear modulus 16 GPa
Bulk modulus 65 GPa
Mohs hardness 2.25
Brinell hardness 180–270 MPa
CAS Registry Number 13494-80-9
History
Naming after Roman Tellus, deity of the Earth
Discovery Franz-Joseph Müller von Reichenstein (1782)
First isolation Martin Heinrich Klaproth
· references

Tellurium is the element with symbol Te and atomic number 52.

Properties

Chemical

It is usually found in -2, +2, +4 and +6 oxidation states. It has chemical properties similar to selenium, being dissolved by sulfuric and nitric acid and potassium hydroxide solutions but not in water. It corrodes copper, iron, and stainless steel in its molten state. It reacts with oxygen in air, hydrogen, and halogens. It burns with a blueish-grey flame. Although being mildly toxic, it is infamous for making you smell really bad so don´t handle it without correct safety equipment.

Physical

Tellurium is a whitish-silvery solid, crystalline element that has a nice, metallic luster. It's a brittle and easily powdered metalloid. tellurium is a good semiconductor, and conductivity increases slightly when exposed to light. It melts at 450 ºC and boils at almost 1000 ºC.

Availability

Tellurium is one of the rarest stable elements on Earth's crust. Applications are scarce, most commonly used in electronics and solar panels. Prices are high and it has few uses for home chemists, in addition to collecting elements.

Rewritable disks contain a small layer of tellurium oxide, though you will need dozens if not hundreds to isolate a significant amount of elemental tellurium.

Tellurium is sometimes found in its native (i.e., elemental) form, but is more often found as the tellurides of gold such as calaverite and krennerite (two different polymorphs of AuTe2), petzite, Ag3AuTe2, and sylvanite, AgAuTe4.

Production

Tellurium can be prepared by reducing tellurium compounds, like metal tellurides. The procedure is very hazardous, as hydrogen telluride may form during the process. Purchasing the free element may be cheaper.

Gold, silver, copper tellurides are roasted with sodium carbonate under air at temperatures of 500 °C. The metal ions are reduced to the metals, while the telluride is converted to sodium tellurite.

M2Te + O2 + Na2CO3 → Na2TeO3 + 2 M + CO2

Tellurites can be leached from the mixture with water and are normally present as hydrotellurites HTeO3 in solution. Selenites may also be formed during this process if any selenides are present, but they can be separated by adding sulfuric acid. The hydrotellurites are converted into the insoluble tellurium dioxide, while the selenites stay in solution.

HTeO
3
+ OH + H2SO4 → TeO2 + SO2−
4
+ 2 H2O

Elemental tellurium is obtained by reducing the oxide either by electrolysis or by reacting the tellurium dioxide with sulfur dioxide in sulfuric acid.

TeO2 + 2 SO2 + 2H2O → Te + 2 SO2−
4
+ 4 H+

The above procedure may not work on other tellurides, like cadmium telluride.

Projects

  • Make tellurium dioxide
  • Make sodium tellurite
  • Element collecting

Handling

Safety

Wear appropriate protection when handling it or it's compounds. Certain compounds such as cadmium telluride are highly toxic.

When small amounts are ingested, tellurium and its compounds are metabolized to dimethyl telluride, causing a foul garlic-like odor named "tellurium breath".

Storage

Tellurium should be stored in closed containers.

Disposal

Since tellurium is rare and expensive, it's best to try to recycle it.

References

Relevant Scencemadness threads