Difference between revisions of "Caesium"

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'''Caesium''' or '''cesium''' is an alkali metal with the chemical symbol '''Cs''' and atomic number 55. It is the heaviest, stable alkali metal.
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{{Infobox element
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<!-- General properties -->
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|name=Caesium
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|symbol=Cs
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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=Pale gold
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<!-- Periodic table -->
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|above=[[Rubidium|Rb]]
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|below=Fr
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|left=[[Xenon]]
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|right=[[Barium]]
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|number=55
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|atomic mass=132.90545196(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=
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|series ref=
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|series comment=
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|series color=
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|group= 1
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|group ref=
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|group comment=(alkali metals)
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|period=6
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|period ref=
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|period comment=
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|block=s
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|block ref=
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|block comment=
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|electron configuration=[Xe] 6s<sup>1</sup>
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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, 8, 1
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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=Pale gold
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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=301.7
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|melting point C=28.5
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|melting point F=83.3
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|melting point ref=
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|melting point comment=
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|boiling point K=944
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|boiling point C=671
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|boiling point F=​1240
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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=1.93
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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=1.843
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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=1938
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|critical point MPa=9.4
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|critical point ref=
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|critical point comment=
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|heat fusion=2.09
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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=63.9
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|heat vaporization ref=
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|heat vaporization comment=
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|heat capacity=32.21
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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=418
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|vapor pressure 10=469
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|vapor pressure 100=534
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|vapor pressure 1 k=623
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|vapor pressure 10 k=750
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|vapor pressure 100 k=940
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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='''+1''', −1​
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|oxidation states ref=
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|oxidation states comment=(a strongly basic oxide)
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|electronegativity=0.79
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|electronegativity ref=
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|electronegativity comment=
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|ionization energy 1=375.7
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|ionization energy 1 ref=
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|ionization energy 1 comment=
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|ionization energy 2=2234.3
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|ionization energy 2 ref=
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|ionization energy 2 comment=
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|ionization energy 3=3400
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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=265
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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=244±11
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|covalent radius ref=
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|covalent radius comment=
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|Van der Waals radius=343
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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=
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|crystal structure prefix=
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|crystal structure ref=
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|crystal structure comment=Body-centred cubic (bcc)
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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=
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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=
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|thermal expansion ref=
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|thermal expansion comment=
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|thermal expansion at 25=97
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|thermal expansion at 25 ref=
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|thermal expansion at 25 comment=
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|thermal conductivity=35.9
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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=205·10<sup>-9</sup>
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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=Paramagnetic
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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=1.7
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|Young's modulus ref=
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|Young's modulus comment=
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|Shear modulus=
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|Shear modulus ref=
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|Shear modulus comment=
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|Bulk modulus=1.6
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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=0.2
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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=0.14
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|Brinell hardness ref=
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|Brinell hardness comment=
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|CAS number=7440-46-2
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|CAS number ref=
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|CAS number comment=
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<!-- History -->
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|naming=From Latin ''caesius'' - sky blue, for its spectral colours
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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= Robert Bunsen and Gustav Kirchhoff
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|discovery date ref=
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|discovery date=1860
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|first isolation by= Carl Setterberg
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|first isolation date ref=
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|first isolation date=1882
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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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}}
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'''Caesium''' or '''cesium''' is an alkali metal with the chemical symbol '''Cs''' and atomic number 55. It is the heaviest, stable [[alkali metal]].
  
 
==Properties==
 
==Properties==
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Caesium is an extremely reactive metal an will spontaneously ignite in air to form caesium oxides and hydroxides. The reaction with [[water]] is explosive, capable of shattering the water's glass container.
 
Caesium is an extremely reactive metal an will spontaneously ignite in air to form caesium oxides and hydroxides. The reaction with [[water]] is explosive, capable of shattering the water's glass container.
  
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:Cs + H<sub>2</sub>O → CsOH + ½ H<sub>2</sub>
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: Cs + H<sub>2</sub>O → CsOH + ½ H<sub>2</sub>
  
 
Caesium also forms two unusual acid nitrates, CsNO<sub>3</sub>·HNO<sub>3</sub> and CsNO<sub>3</sub>·2HNO<sub>3</sub>
 
Caesium also forms two unusual acid nitrates, CsNO<sub>3</sub>·HNO<sub>3</sub> and CsNO<sub>3</sub>·2HNO<sub>3</sub>
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==Availability==
 
==Availability==
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Cesium ampoules can be purchased from [http://www.mcssl.com/store/gallium-source/019---cesium-metal GalliumSource], however it is extremely expensive, a 100 g ampoule is 2400 $ and a 1 g one is 140$. Another seller, [http://www.smart-elements.com/Cs SmartElements] sells cesium ampoules cheaper, a 10 g ampoule is 179 € while a 1 g ampoule is only 79 €.
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Cesium ampoules can be purchased from [http://www.mcssl.com/store/gallium-source/019---cesium-metal GalliumSource], however it is extremely expensive, a 100 g ampoule is 2400 $ and a small 1 g one is 140 $. Another seller, [http://www.smart-elements.com/Cs SmartElements] sells cesium ampoules cheaper, a 10 g ampoule is 179 € while a 1 g ampoule is only 79 €.
  
 
Very small amounts of cesium alloys are used in the cathode of the electron gun from the cathode ray tube TVs.<ref>http://www.madehow.com/Volume-2/Cathode-Ray-Tube.html</ref> The exact composition of the alloy varies, depending on the generation of tube, as not all of them have cesium.<ref>http://en.wikipedia.org/wiki/Photocathode#Photocathode_materials</ref>
 
Very small amounts of cesium alloys are used in the cathode of the electron gun from the cathode ray tube TVs.<ref>http://www.madehow.com/Volume-2/Cathode-Ray-Tube.html</ref> The exact composition of the alloy varies, depending on the generation of tube, as not all of them have cesium.<ref>http://en.wikipedia.org/wiki/Photocathode#Photocathode_materials</ref>
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Because it's extremely reactive, isolating pure caesium metal is extremely difficult. One way is to reduce caesium halides with a reactive metal such as [[calcium]], [[barium]], or [[lithium]] at 700-800 °C, followed by distillation of the caesium metal. YouTube vlogger thunderf00t has performed this preparation, as it seems to be much cheaper to perform this extraction than it is to buy the metal (but it is far more convenient to just buy the metal).
 
Because it's extremely reactive, isolating pure caesium metal is extremely difficult. One way is to reduce caesium halides with a reactive metal such as [[calcium]], [[barium]], or [[lithium]] at 700-800 °C, followed by distillation of the caesium metal. YouTube vlogger thunderf00t has performed this preparation, as it seems to be much cheaper to perform this extraction than it is to buy the metal (but it is far more convenient to just buy the metal).
  
−
Purer caesium metal can also be prepared by decomposing [[cesium azide|caesium azide]] in vacuum at 390 °C, which is prepared from caesium sulfate and [[barium azide]].
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Purer caesium metal can also be prepared by decomposing [[caesium azide]] in vacuum at 390 °C, which is prepared from caesium sulfate and [[barium azide]].
  
 
Electrolytic preparation of elemental cesium is extremely difficult. Caesium chloride for example, melts at at 645 °C, while cesium metal boils at 671 °C, so without a sensitive temperature controller there's a risk of boiling the metal. This boiling, however, tends to drive isolation reactions forward by increasing entropy.
 
Electrolytic preparation of elemental cesium is extremely difficult. Caesium chloride for example, melts at at 645 °C, while cesium metal boils at 671 °C, so without a sensitive temperature controller there's a risk of boiling the metal. This boiling, however, tends to drive isolation reactions forward by increasing entropy.
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==Projects==
 
==Projects==
 
*Alkali water explosion
 
*Alkali water explosion
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*[[Cesium hydroxide]] synthesis
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*[[Caesium hydroxide]] synthesis
 
*Cesium auride synthesis
 
*Cesium auride synthesis
  
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[[Category:Materials that react with water]]
 
[[Category:Materials that react with water]]
 
[[Category:S-block]]
 
[[Category:S-block]]
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[[Category:Air-sensitive materials]]
 
[[Category:Pyrophoric materials]]
 
[[Category:Pyrophoric materials]]

Latest revision as of 16:25, 2 January 2022

Caesium,  55Cs
General properties
Name, symbol Caesium, Cs
Appearance Pale gold
Caesium in the periodic table
Rb
↑
Cs
↓
Fr
Xenon ← Caesium → Barium
Atomic number 55
Standard atomic weight (Ar) 132.90545196(6)
Group, block (alkali metals); s-block
Period period 6
Electron configuration [Xe] 6s1
per shell
 2, 8, 18, 18, 8, 1
Physical properties
Pale gold
Phase Solid
Melting point 301.7 K ​(28.5 °C, ​83.3 °F)
Boiling point 944 K ​(671 °C, ​​1240 °F)
Density near r.t. 1.93 g/cm3
when liquid, at  1.843 g/cm3
Critical point 1938 K, 9.4 MPa
Heat of fusion 2.09 kJ/mol
Heat of 63.9 kJ/mol
Molar heat capacity 32.21 J/(mol·K)
 pressure
Atomic properties
Oxidation states +1, −1​ ​(a strongly basic oxide)
Electronegativity Pauling scale: 0.79
energies 1st: 375.7 kJ/mol
2nd: 2234.3 kJ/mol
3rd: 3400 kJ/mol
Atomic radius empirical: 265 pm
Covalent radius 244±11 pm
Van der Waals radius 343 pm
Miscellanea
Crystal structure ​Body-centred cubic (bcc)
Thermal expansion 97 µm/(m·K) (at 25 °C)
Thermal conductivity 35.9 W/(m·K)
Electrical resistivity 205·10-9 Ω·m (at 20 °C)
Magnetic ordering Paramagnetic
Young's modulus 1.7 GPa
Bulk modulus 1.6 GPa
Mohs hardness 0.2
Brinell hardness 0.14 MPa
CAS Registry Number 7440-46-2
History
Naming From Latin caesius - sky blue, for its spectral colours
Discovery Robert Bunsen and Gustav Kirchhoff (1860)
First isolation Carl Setterberg (1882)
· references

Caesium or cesium is an alkali metal with the chemical symbol Cs and atomic number 55. It is the heaviest, stable alkali metal.

Properties

Chemical

Caesium is an extremely reactive metal an will spontaneously ignite in air to form caesium oxides and hydroxides. The reaction with water is explosive, capable of shattering the water's glass container.

Cs + H2O → CsOH + ½ H2

Caesium also forms two unusual acid nitrates, CsNO3·HNO3 and CsNO3·2HNO3

Caesium hydroxide is extremely corrosive and attack glass much faster than the other alkali hydroxides.

Physical

Caesium is a soft alkali metal, silvery-gold in color. It has a very low melting point of 28 °C, meaning it can be a liquid at near room temperature or if held in one's hand. It is the least electronegative element and is extremely reactive and even pyrophoric. It will react with water even at temperatures as low as −116 °C.

Availability

Cesium ampoules can be purchased from GalliumSource, however it is extremely expensive, a 100 g ampoule is 2400 $ and a small 1 g one is 140 $. Another seller, SmartElements sells cesium ampoules cheaper, a 10 g ampoule is 179 € while a 1 g ampoule is only 79 €.

Very small amounts of cesium alloys are used in the cathode of the electron gun from the cathode ray tube TVs.[1] The exact composition of the alloy varies, depending on the generation of tube, as not all of them have cesium.[2]

Cesium compounds, such as cesium formate, are used as drilling fluids.

Preparation

Because it's extremely reactive, isolating pure caesium metal is extremely difficult. One way is to reduce caesium halides with a reactive metal such as calcium, barium, or lithium at 700-800 °C, followed by distillation of the caesium metal. YouTube vlogger thunderf00t has performed this preparation, as it seems to be much cheaper to perform this extraction than it is to buy the metal (but it is far more convenient to just buy the metal).

Purer caesium metal can also be prepared by decomposing caesium azide in vacuum at 390 °C, which is prepared from caesium sulfate and barium azide.

Electrolytic preparation of elemental cesium is extremely difficult. Caesium chloride for example, melts at at 645 °C, while cesium metal boils at 671 °C, so without a sensitive temperature controller there's a risk of boiling the metal. This boiling, however, tends to drive isolation reactions forward by increasing entropy.

Projects

Handling

Safety

Caesium metal is extremely reactive and pyrophoric in air. Cesium will not usually catch fire just by being exposed to air, but friction, heating, or exposure to water can trigger a fire or explosion.

In its ionic form, caesium ions are extremely similar to potassium and rubidium ions, and its toxicity is just as low as the mentioned elements.

Storage

While it can be stored under mineral oil, it will oxidize much faster than lithium, sodium or potassium, so it is best stored in vacuum containers or argon ampoules. The best way to handle metallic cesium is in a glove box filled with inert gas, such as argon.

Disposal

Cesium metal cannot be safely neutralized by dissolving it in isopropanol, like sodium, as the reaction is just as violent as the one with water. It is best to leave it in air (or in a CO2 atmosphere, as there's a less risk of fire) to turn into oxide, hydroxide and carbonate, that can be safely disposed of.[3] Due to its rarity, it's best to recycle caesium.

References

  1. ↑ http://www.madehow.com/Volume-2/Cathode-Ray-Tube.html
  2. ↑ http://en.wikipedia.org/wiki/Photocathode#Photocathode_materials
  3. ↑ Safety in the Chemistry and Biochemistry Laboratory By André Picot, P. Grenouillet, p. 213

Relevant Sciencemadness threads

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