Difference between revisions of "Tellurium"

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Tellurium is the element with symbol '''Te''' and atomic number 52.
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{{Infobox element
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<!-- top -->
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|image name=Tellurium2.jpg
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|image alt=
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|image size=
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|image name comment=Metallic tellurium, diameter 3.5 cm
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|image name 2=
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|image alt 2=
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|image size 2=
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|image name 2 comment=
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<!-- General properties -->
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|name=Tellurium
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|symbol=Te
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|pronounce=
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|pronounce ref=
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|pronounce comment=
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|pronounce 2=
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|alt name=
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|alt names=
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|allotropes=
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|appearance=silvery lustrous gray (crystalline),
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brown-black powder (amorphous)
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<!-- Periodic table -->
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|above=[[Selenium|Se]]
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|below=[[Polonium|Po]]
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|left=[[Antimony]]
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|right=[[Iodine]]
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|number=52
 +
|atomic mass=127.6
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|atomic mass 2=
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|atomic mass ref=
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|atomic mass comment=
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|series=Chalcogens
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|series ref=
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|series comment=Chalcogens
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|series color=
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|group=16
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|group ref=
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|group comment=16
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|period=4
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|period ref=
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|period comment=
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|block=p
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|block ref=
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|block comment=
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|electron configuration=[Kr] 4d10 5s2 5p4
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|electron configuration ref=
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|electron configuration comment=
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|electrons per shell=2, 8, 18, 18, 6
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|electrons per shell ref=
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|electrons per shell comment=
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<!-- Physical properties -->
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|physical properties comment=
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|color=silvery-gray
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|phase=solid
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|phase ref=
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|phase comment=
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|melting point K=722.66
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|melting point C=449.51
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|melting point F=​841.12
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|melting point ref=
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|melting point comment=
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|boiling point K=1261
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|boiling point C=988
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|boiling point F=1810
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|boiling point ref=
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|boiling point comment=
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|sublimation point K=
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|sublimation point C=
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|sublimation point F=
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|sublimation point ref=
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|sublimation point comment=
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|density gplstp=
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|density gplstp ref=
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|density gplstp comment=
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|density gpcm3nrt=6.24
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|density gpcm3nrt ref=
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|density gpcm3nrt comment=
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|density gpcm3nrt 2=
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|density gpcm3nrt 2 ref=
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|density gpcm3nrt 2 comment=
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|density gpcm3nrt 3=
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|density gpcm3nrt 3 ref=
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|density gpcm3nrt 3 comment=
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|density gpcm3mp=5.70
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|density gpcm3mp ref=
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|density gpcm3mp comment=
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|density gpcm3bp=
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|density gpcm3bp ref=
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|density gpcm3bp comment=
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|molar volume=
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|molar volume unit =
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|molar volume ref=
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|molar volume comment=
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|triple point K=
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|triple point kPa=
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|triple point ref=
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|triple point comment=
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|triple point K 2=
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|triple point kPa 2=
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|triple point 2 ref=
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|triple point 2 comment=
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|critical point K=
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|critical point MPa=
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|critical point ref=
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|critical point comment=
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|heat fusion=17.49
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|heat fusion ref=
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|heat fusion comment=
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|heat fusion 2=
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|heat fusion 2 ref=
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|heat fusion 2 comment=
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|heat vaporization=114.1
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|heat vaporization ref=
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|heat vaporization comment=
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|heat capacity=25.73
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|heat capacity ref=
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|heat capacity comment=
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|heat capacity 2=
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|heat capacity 2 ref=
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|heat capacity 2 comment=
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|vapor pressure 1=
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|vapor pressure 10=
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|vapor pressure 100=(775)
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|vapor pressure 1 k=(888)
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|vapor pressure 10 k=1042
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|vapor pressure 100 k=1266
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|vapor pressure ref=
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|vapor pressure comment=
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|vapor pressure 1 2=
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|vapor pressure 10 2=
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|vapor pressure 100 2=
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|vapor pressure 1 k 2=
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|vapor pressure 10 k 2=
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|vapor pressure 100 k 2=
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|vapor pressure 2 ref=
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|vapor pressure 2 comment=
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<!-- Atomic properties -->
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|atomic properties comment=
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|oxidation states=6, 5, 4, 3, 2, 1, −1, −2
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|oxidation states ref=
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|oxidation states comment=a mildly acidic oxide
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|electronegativity=2.1
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|electronegativity ref=
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|electronegativity comment=
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|ionization energy 1=869.3
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|ionization energy 1 ref=
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|ionization energy 1 comment=
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|ionization energy 2=1790
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|ionization energy 2 ref=
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|ionization energy 2 comment=
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|ionization energy 3=2698
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|ionization energy 3 ref=
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|ionization energy 3 comment=
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|number of ionization energies=
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|ionization energy ref=
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|ionization energy comment=
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|atomic radius=140
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|atomic radius ref=
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|atomic radius comment=
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|atomic radius calculated=
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|atomic radius calculated ref=
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|atomic radius calculated comment=
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|covalent radius=138±4
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|covalent radius ref=
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|covalent radius comment=
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|Van der Waals radius=206
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|Van der Waals radius ref=
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|Van der Waals radius comment=
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<!-- Miscellanea -->
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|crystal structure=​hexagonal
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|crystal structure prefix=
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|crystal structure ref=
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|crystal structure comment=
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|crystal structure 2=
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|crystal structure 2 prefix=
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|crystal structure 2 ref=
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|crystal structure 2 comment=
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|speed of sound=
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|speed of sound ref=
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|speed of sound comment=
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|speed of sound rod at 20=2610
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|speed of sound rod at 20 ref=
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|speed of sound rod at 20 comment=
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|speed of sound rod at r.t.=
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|speed of sound rod at r.t. ref=
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|speed of sound rod at r.t. comment=
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|thermal expansion=18
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|thermal expansion ref=
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|thermal expansion comment=
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|thermal expansion at 25=
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|thermal expansion at 25 ref=
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|thermal expansion at 25 comment=
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|thermal conductivity=1.97–3.38
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|thermal conductivity ref=
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|thermal conductivity comment=
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|thermal conductivity 2=
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|thermal conductivity 2 ref=
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|thermal conductivity 2 comment=
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|thermal diffusivity=
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|thermal diffusivity ref=
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|thermal diffusivity comment=
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|electrical resistivity=
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|electrical resistivity unit prefix=
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|electrical resistivity ref=
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|electrical resistivity comment=
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|electrical resistivity at 0=
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|electrical resistivity at 0 ref=
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|electrical resistivity at 0 comment=
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|electrical resistivity at 20=
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|electrical resistivity at 20 ref=
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|electrical resistivity at 20 comment=
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|band gap=
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|band gap ref=
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|band gap comment=
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|Curie point K=
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|Curie point ref=
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|Curie point comment=
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|magnetic ordering=diamagnetic
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|magnetic ordering ref=
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|magnetic ordering comment=
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|tensile strength=
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|tensile strength ref=
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|tensile strength comment=
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|Young's modulus=43
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|Young's modulus ref=
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|Young's modulus comment=
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|Shear modulus=16
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|Shear modulus ref=
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|Shear modulus comment=
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|Bulk modulus=65
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|Bulk modulus ref=
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|Bulk modulus comment=
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|Poisson ratio=
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|Poisson ratio ref=
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|Poisson ratio comment=
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|Mohs hardness=2.25
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|Mohs hardness ref=
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|Mohs hardness comment=
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|Mohs hardness 2=
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|Mohs hardness 2 ref=
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|Mohs hardness 2 comment=
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|Vickers hardness=
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|Vickers hardness ref=
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|Vickers hardness comment=
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|Brinell hardness=180–270
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|Brinell hardness ref=
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|Brinell hardness comment=
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|CAS number=13494-80-9
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|CAS number ref=
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|CAS number comment=
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<!-- History -->
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|naming=after Roman Tellus, deity of the Earth
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|predicted by=
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|prediction date ref=
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|prediction date=
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|discovered by=Franz-Joseph Müller von Reichenstein
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|discovery date ref=
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|discovery date=1782
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|first isolation by=Martin Heinrich Klaproth
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|first isolation date ref=
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|first isolation date=
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|discovery and first isolation by=
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|named by=
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|named date ref=
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|named date=
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|history comment label=
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|history comment=
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<!-- Isotopes -->
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|isotopes=
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|isotopes comment=
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|engvar=
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}}
 +
'''Tellurium''' is the element with symbol '''Te''' and atomic number 52.
  
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== Chemical Properties ==
+
==Properties==
−
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 midly toxic, it is infamous for making you smell really bad so don´t handle it without correct safety equipment.
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=== Chemical ===
 +
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.
  
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== Physical Properties ==
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=== Physical ===
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It is a solid, whitish-silvery, 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 Cº and boils at almost 1000 Cº.
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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 adittion 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.
  
−
== Safety ==
+
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.
−
Wear appropiate protection when handling it or it's compounds. Cadmium telluride is highly toxic.
+
 
 +
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==
 +
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==
 +
*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==
 +
<references/>
 +
===Relevant Scencemadness threads===
 +
*[http://www.sciencemadness.org/talk/viewthread.php?tid=63173 Tellurium]
 +
*[http://www.sciencemadness.org/talk/viewthread.php?tid=30801 tellurium at a good price]
 +
*[http://www.sciencemadness.org/talk/viewthread.php?tid=23294 quite the silly question: Tellerium]
  
 
[[Category:Elements]]
 
[[Category:Elements]]
 
[[Category:Metalloids]]
 
[[Category:Metalloids]]
 
[[Category:Chalcogens]]
 
[[Category:Chalcogens]]
 +
[[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
Antimony ← Tellurium → Iodine
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

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