Difference between revisions of "Europium"

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'''Europium''' is a [[lanthanide]] with the symbol Eu and atomic number 63. It is a steel-gray metal about as reactive as calcium. Although difficult to find and rather expensive, it and its salts have very interesting properties that make it an excellent addition to the amateur chemist's lab. Among these properties are multi-colored [[fluorescence]], [[redox|redox chemistry]] and [[paramagnetism]], brought about by the element's half-filled f-shell. Europium can exist in a +2 state in a reducing environment, which can be an excellent exercise in preparing reduced compounds, as the reaction Eu<sup>2+</sup> → Eu<sup>3+</sup> + e<sup>-</sup> is even less favored than [[Chromium|Cr]]<sup>2+</sup> → Cr<sup>3+</sup> + e<sup>-</sup>, which is a standard exercise in the lab.
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{{Infobox element
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<!-- General properties -->
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|name= Europium
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|symbol= Eu
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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 white
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<!-- Periodic table -->
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|above=-
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|below=[[Americium|Am]]
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|left=[[Samarium]]
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|right=[[Gadolinium]]
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|number=63
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|atomic mass=151.964(1)
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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 comment=
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|series color=
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|group=
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|group comment=
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|period=6
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|period ref=
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|period comment=
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|block=f
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|block ref=
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|block comment=
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|electron configuration=[Xe] 4f<sup>7</sup> 6s<sup>2</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, 25, 8, 2
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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-white
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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=1099
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|melting point C=826
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|melting point F=​1519
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|melting point ref=
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|melting point comment=
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|boiling point K=1802
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|boiling point C=1529
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|boiling point F=​2784
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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=5.264
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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 3=
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|density gpcm3mp=5.13
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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 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=9.21
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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=176
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|heat vaporization ref=
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|heat vaporization comment=
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|heat capacity=27.66
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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=863
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|vapor pressure 10=957
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|vapor pressure 100=1072
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|vapor pressure 1 k=1234
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|vapor pressure 10 k=1452
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|vapor pressure 100 k=1796
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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 1 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='''3''', '''2''', 1
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|oxidation states ref=
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|oxidation states comment=(a mildly basic oxide)
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|electronegativity=1.2
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|electronegativity ref=
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|electronegativity comment=
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|ionization energy 1=547.1
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|ionization energy 1 ref=
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|ionization energy 1 comment=
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|ionization energy 2=1085
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|ionization energy 2 ref=
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|ionization energy 2 comment=
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|ionization energy 3=2404
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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=180
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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=198±6
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|covalent radius ref=
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|covalent radius comment=
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|Van der Waals radius=
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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-centered cubic (bcc)
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|crystal structure 2=
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|crystal structure 2 prefix=
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|crystal structure 2 comment=
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|speed of sound=
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|speed of sound rod at 20=
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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=35.0
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|thermal expansion ref=
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|thermal expansion comment=(poly)
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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=13.9
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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 comment=
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|electrical resistivity=9·10<sup>-7</sup>
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|electrical resistivity unit prefix=
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|electrical resistivity comment=(poly)
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|electrical resistivity at 0=
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|electrical resistivity at 0 ref=
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|electrical resistivity at 20=
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|electrical resistivity at 20 ref=
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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=18.2
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|Young's modulus ref=
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|Young's modulus comment=
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|Shear modulus=7.9
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|Shear modulus ref=
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|Shear modulus comment=
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|Bulk modulus=8.3
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|Bulk modulus ref=
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|Bulk modulus comment=
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|Poisson ratio=0.152
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|Poisson ratio ref=
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|Poisson ratio comment=
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|Mohs hardness=
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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=165–200
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|Vickers hardness ref=
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|Vickers hardness comment=
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|Brinell hardness=
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|Brinell hardness comment=
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|CAS number=7440-53-1
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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 Europe
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|predicted by=
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|discovered by=
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|discovery date=
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|first isolation by=
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|first isolation date=
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|discovery and first isolation by=Eugène-Anatole Demarçay (1896, 1901)
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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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'''Europium''' is a [[lanthanide]] with the symbol '''Eu''' and atomic number 63. It is a steel-gray metal about as reactive as [[calcium]]. Although difficult to find and rather expensive, this metal and its salts have very interesting properties that make it an excellent addition to the amateur chemist's lab. Among these properties are multi-colored [[fluorescence]], [[redox|redox chemistry]] and [[paramagnetism]], brought about by the element's half-filled f-shell. Europium can exist in a +2 state in a reducing environment, which can be an excellent exercise in preparing reduced compounds, as the reaction Eu<sup>2+</sup> → Eu<sup>3+</sup> + e<sup>-</sup> is even less favored than [[Chromium|Cr]]<sup>2+</sup> → Cr<sup>3+</sup> + e<sup>-</sup>, which is a standard exercise in the lab.
  
 
==Properties==
 
==Properties==
−
===Chemical===
 
−
Europium is by far the most reactive lanthanide, quickly corroding in air. The highly favorable reaction Eu → Eu<sup>2+</sup> + e<sup>-</sup> and the increased stability of europium(II) accelerates the corrosion rate of the metal such that a small piece exposed to dry air will corrode within a month. The resulting yellow powder, nearly the color of mustard, slowly fades as it turns from europium(II) to europium(III), the most stable form of europium. [[Europium(II,III) oxide|A mixed oxide of europium(II) and europium(III)]] has been reported, as have [[europium(II) sulfide]], [[europium(II) chloride]], and [[europium(II) sulfate]], which is very similar to [[calcium sulfate|calcium]] and [[barium sulfate]] and highly insoluble.
 
−
 
−
Europium metal burns in air with a bright red flame, identical to that of [[samarium]], and forms the oxide in air. When europium contacts water, it will react with water about as quickly as [[calcium]] metal, and will form the yellow [[Europium(II) hydroxide|divalent hydroxide]], which slowly converts to the [[Europium(III) hydroxide|trivalent hydroxide]].
 
  
 
===Physical===
 
===Physical===
−
Freshly cut europium is grayish, but quickly develops a thick layer of yellow and graphite-colored oxides. It is a relatively soft metal, and is relatively soft. Europium(II) compounds exhibit a blue fluorescence, and europium(III) compounds exhibit a red fluorescence. The fluorescence may be enhanced by the complexation of [[Dipicolinic acid|dipicolinate]] or other planar ligands to a europium atom.
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Freshly cut europium is grayish, but quickly develops a thick layer of yellow and graphite-colored oxides. It is a relatively soft metal, softer than other lanthanides, and can be cut with a cutting tool. Europium(II) compounds exhibit a blue fluorescence (though this varies significantly with the coordinating ligands), and europium(III) compounds exhibit a red fluorescence. The fluorescence may be enhanced by the complexation of [[Dipicolinic acid|dipicolinate]] or other planar ligands to a europium atom.
 +
 
 +
===Chemical===
 +
Europium is by far the most reactive lanthanide, quickly corroding in air. The highly favorable reaction Eu → Eu<sup>2+</sup> + e<sup>-</sup> and the increased stability of europium(II) accelerates the corrosion rate of the metal such that a small piece exposed to dry air will corrode within a month. The resulting yellow powder, nearly the color of mustard, slowly fades as it turns from europium(II) to europium(III), the most stable form of europium. [[Europium(II,III) oxide|A mixed oxide of europium(II) and europium(III)]] has been reported, as have [[europium(II) sulfide]], [[europium(II) chloride]], and [[europium(II) sulfate]], which is very similar to [[calcium sulfate|calcium]] and [[barium sulfate]] in that it is highly insoluble in water.
 +
 
 +
Europium metal burns in air with a bright red flame, identical to that of [[samarium]] to form the oxide. When europium contacts water, it will react with water about as quickly as [[calcium]], and will form the yellow [[Europium(II) hydroxide|divalent hydroxide]], which converts to the [[Europium(III) hydroxide|trivalent hydroxide]] on further exposure to water. When dry, it absorbs carbon dioxide from the air to make [[europium(III) carbonate]].
  
 
==Availability==
 
==Availability==
Line 17: Line 290:
 
*Producing fluorescent crystals (blue and red)
 
*Producing fluorescent crystals (blue and red)
 
*Producing triboluminescent europium tetrakis(dibenzoylmethide)triethylammonium
 
*Producing triboluminescent europium tetrakis(dibenzoylmethide)triethylammonium
 +
*Element collecting
  
 
==Safety==
 
==Safety==
Line 23: Line 297:
  
 
===Storage===
 
===Storage===
−
Europium requires storage under an inert atmosphere or mineral oil to prevent corrosion. When exposed to air, europium corrodes very easily, and it is not possible to reduce europium compounds to europium metal without an aprotic solvent.
+
Europium requires storage under an inert atmosphere or mineral oil to prevent corrosion. To remove mineral oil, rinse it off with toluene or xylene. When exposed to air, europium corrodes very easily, and it is not possible to reduce europium compounds back to europium metal without an aprotic solvent or powerful reductants like potassium. Keep europium away from oxidizers and acids.
  
 
===Disposal===
 
===Disposal===
−
Best to try to recycle it.
+
Since europium is expensive, it's best to try to recycle it.
  
 
==References==
 
==References==
 
<references/>
 
<references/>
 
===Relevant Sciencemadness threads===
 
===Relevant Sciencemadness threads===
−
[https://www.sciencemadness.org/whisper/viewthread.php?tid=29670 Production and storage of europium(II) compounds]
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*[https://www.sciencemadness.org/whisper/viewthread.php?tid=29670 Production and storage of europium(II) compounds]
  
 
[[Category:Elements]]
 
[[Category:Elements]]
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[[Category:Materials that react with water]]
 
[[Category:Materials that react with water]]
 
[[Category:Materials unstable in acidic solution]]
 
[[Category:Materials unstable in acidic solution]]
 +
[[Category:Air-sensitive materials]]
 
[[Category:F-block]]
 
[[Category:F-block]]

Latest revision as of 21:15, 11 July 2021

Europium,  63Eu
General properties
Name, symbol Europium, Eu
Appearance Silvery white
Europium in the periodic table
-
↑
Eu
↓
Am
Samarium ← Europium → Gadolinium
Atomic number 63
Standard atomic weight (Ar) 151.964(1)
Group, block , f-block
Period period 6
Electron configuration [Xe] 4f7 6s2
per shell
 2, 8, 18, 25, 8, 2
Physical properties
Silvery-white
Phase Solid
Melting point 1099 K ​(826 °C, ​​1519 °F)
Boiling point 1802 K ​(1529 °C, ​​2784 °F)
Density near r.t. 5.264 g/cm3
when liquid, at  5.13 g/cm3
Heat of fusion 9.21 kJ/mol
Heat of 176 kJ/mol
Molar heat capacity 27.66 J/(mol·K)
 pressure
Atomic properties
Oxidation states 3, 2, 1 ​(a mildly basic oxide)
Electronegativity Pauling scale: 1.2
energies 1st: 547.1 kJ/mol
2nd: 1085 kJ/mol
3rd: 2404 kJ/mol
Atomic radius empirical: 180 pm
Covalent radius 198±6 pm
Miscellanea
Crystal structure ​Body-centered cubic (bcc)
Thermal expansion 35.0 µm/(m·K) (poly)
Thermal conductivity 13.9 W/(m·K)
Electrical resistivity 9·10-7 Ω·m (poly)
Magnetic ordering Paramagnetic
Young's modulus 18.2 GPa
Shear modulus 7.9 GPa
Bulk modulus 8.3 GPa
Poisson ratio 0.152
Vickers hardness 165–200 MPa
CAS Registry Number 7440-53-1
History
Naming After Europe
Discovery and first isolation Eugène-Anatole Demarçay (1896, 1901)
· references

Europium is a lanthanide with the symbol Eu and atomic number 63. It is a steel-gray metal about as reactive as calcium. Although difficult to find and rather expensive, this metal and its salts have very interesting properties that make it an excellent addition to the amateur chemist's lab. Among these properties are multi-colored fluorescence, redox chemistry and paramagnetism, brought about by the element's half-filled f-shell. Europium can exist in a +2 state in a reducing environment, which can be an excellent exercise in preparing reduced compounds, as the reaction Eu2+ → Eu3+ + e- is even less favored than Cr2+ → Cr3+ + e-, which is a standard exercise in the lab.

Properties

Physical

Freshly cut europium is grayish, but quickly develops a thick layer of yellow and graphite-colored oxides. It is a relatively soft metal, softer than other lanthanides, and can be cut with a cutting tool. Europium(II) compounds exhibit a blue fluorescence (though this varies significantly with the coordinating ligands), and europium(III) compounds exhibit a red fluorescence. The fluorescence may be enhanced by the complexation of dipicolinate or other planar ligands to a europium atom.

Chemical

Europium is by far the most reactive lanthanide, quickly corroding in air. The highly favorable reaction Eu → Eu2+ + e- and the increased stability of europium(II) accelerates the corrosion rate of the metal such that a small piece exposed to dry air will corrode within a month. The resulting yellow powder, nearly the color of mustard, slowly fades as it turns from europium(II) to europium(III), the most stable form of europium. A mixed oxide of europium(II) and europium(III) has been reported, as have europium(II) sulfide, europium(II) chloride, and europium(II) sulfate, which is very similar to calcium and barium sulfate in that it is highly insoluble in water.

Europium metal burns in air with a bright red flame, identical to that of samarium to form the oxide. When europium contacts water, it will react with water about as quickly as calcium, and will form the yellow divalent hydroxide, which converts to the trivalent hydroxide on further exposure to water. When dry, it absorbs carbon dioxide from the air to make europium(III) carbonate.

Availability

Europium is more common than iodine on Earth, but it is hard to find and extremely expensive. Places like Sigma-Aldrich charge $1000 for five measly grams.[1] One source for europium, as well as other rare earth metals, is Metallium. It is sold in 5 gram (thankfully only $50) and 25 gram sizes, as well as rods, ampoules, and coins. Metallium also takes custom orders. Europium and its compounds may be occasionally found on eBay. Other places such as NewMet will sell europium rods, sheets, foils at any size and no minimum order, though the price is on request.

Projects

  • Preparing reduced europium compounds
  • Producing fluorescent crystals (blue and red)
  • Producing triboluminescent europium tetrakis(dibenzoylmethide)triethylammonium
  • Element collecting

Safety

Safety

Europium metal, especially as a dust, should always be kept away from water and open flames. Europium fires can be identified by their bright red flames. Never use water to put out europium fire, as this will aggravate it. Class D fire extinguishers are recommended for this type of fire.

Storage

Europium requires storage under an inert atmosphere or mineral oil to prevent corrosion. To remove mineral oil, rinse it off with toluene or xylene. When exposed to air, europium corrodes very easily, and it is not possible to reduce europium compounds back to europium metal without an aprotic solvent or powerful reductants like potassium. Keep europium away from oxidizers and acids.

Disposal

Since europium is expensive, it's best to try to recycle it.

References

  1. ↑ Seriously, Sigma? http://www.sigmaaldrich.com/catalog/product/aldrich/457965?lang=en&region=US

Relevant Sciencemadness threads

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