Difference between revisions of "Samarium"

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[[File:Samarium_tree_by_diddi.png|thumb|400px|A truly massive 750g chunk of samarium owned by diddi.]]
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{{Infobox element
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'''Samarium''' is a lanthanide with the symbol '''Sm''' and atomic number 62. It is a grayish-silvery metal, with similar reactivity to [[magnesium]]. Its chemical behavior is similar to most other [[rare earth metals|rare earth metal]], but it is notable for the presence of a blood-red samarium (II) ion in reducing conditions.
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<!-- top -->
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|image name=Samarium shards 4k.jpg
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|image alt=
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|image size=300
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|image name comment=Samarium metal
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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=Samarium
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|symbol=Sm
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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 gray
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<!-- Periodic table -->
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|above=-
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|below=[[Plutonium|Pu]]
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|left=[[Promethium]]
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|right=[[Europium]]
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|number=62
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|atomic mass=150.36(2)
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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=
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|group ref=
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|group comment= n/a
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|period=6
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|period ref=
 +
|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>6</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, 24, 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-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=1345
 +
|melting point C=1072
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|melting point F=​1962
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|melting point ref=
 +
|melting point comment=
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|boiling point K=2173
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|boiling point C=1900
 +
|boiling point F=​3452
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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=7.52
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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=7.16
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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=8.62
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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=192
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|heat vaporization ref=
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|heat vaporization comment=
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|heat capacity=29.54
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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=1001
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|vapor pressure 10=1106
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|vapor pressure 100=1240
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|vapor pressure 1 k=(1421)
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|vapor pressure 10 k=(1675)
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|vapor pressure 100 k=(2061)
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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=4, '''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=1.17
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|electronegativity ref=
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|electronegativity comment=
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|ionization energy 1=544.5
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|ionization energy 1 ref=
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|ionization energy 1 comment=
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|ionization energy 2=1070
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|ionization energy 2 ref=
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|ionization energy 2 comment=
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|ionization energy 3=2260
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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±8
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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=Rhombohedral
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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=2130
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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=12.7
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|thermal expansion ref=
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|thermal expansion comment=(α, 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=13.3
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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=9.4·10<sup>-7</sup>
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|electrical resistivity unit prefix=
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|electrical resistivity ref=
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|electrical resistivity comment=(α, 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 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=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=49.7
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|Young's modulus ref=
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|Young's modulus comment=(α form)
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|Shear modulus=19.5
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|Shear modulus ref=
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|Shear modulus comment=(α form)
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|Bulk modulus=37.8
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|Bulk modulus ref=
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|Bulk modulus comment=(α form)
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|Poisson ratio=0.274
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|Poisson ratio ref=
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|Poisson ratio comment=(α form)
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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=410–440
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|Vickers hardness ref=
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|Vickers hardness comment=
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|Brinell hardness=440–600
 +
|Brinell hardness ref=
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|Brinell hardness comment=
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|CAS number=7440-19-9
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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 the mineral samarskite (itself named after Vassili Samarsky-Bykhovets)
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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=
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|discovery date ref=
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|discovery date=
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|first isolation by=
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|first isolation date ref=
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|first isolation date=
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|discovery and first isolation by=Lecoq de Boisbaudran (1879)
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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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}}
 +
'''Samarium''' is a lanthanide with the symbol '''Sm''' and atomic number 62. It is a grayish-silvery metal, with similar reactivity to [[magnesium]]. Its chemical behavior is similar to most other [[rare earth metal]]s, but it is notable for the presence of a blood-red samarium (II) ion in reducing conditions.
  
 
==Properties==
 
==Properties==
 
===Physical properties===
 
===Physical properties===
−
Samarium is a grayish metal that is about as dense as [[iron]] or [[manganese]]. Freshly cut pieces are very shiny and lustrous, while older ones are generally darker from a thin oxide layer. It is very slightly paramagnetic - more so than [[vanadium]], but less than [[europium]], and can be very easily demonstrated by placing a piece on a styrofoam block on water and pulling it with a [[neodymium magnet]].
+
Samarium is a grayish metal that is about as dense as [[iron]] or [[manganese]]. Freshly cut pieces are very shiny and lustrous, while older ones are generally darker from a thin oxide layer. It is very slightly paramagnetic - more so than [[vanadium]], but less than [[europium]], and can be very easily demonstrated by placing a piece on a styrofoam block on water and pulling it with a [[Neodymium iron boron magnet|neodymium magnet]].
 +
 
 
===Chemical properties===
 
===Chemical properties===
−
[[File:SmI3_05-1-.jpg|thumb|300px|Samarium after being heated with iodine. Photo by blogfast25.]]
+
As a lanthanide, samarium is quite reactive, but its corrosion resistance is between that of the light and heavy rare earth metals. Exposure to air will eventually turn it to a white powdery oxide, but it is nowhere near as reactive as europium or [[lanthanum]]. It burns in air to from yellowish [[samarium(III) oxide]] in a bright red flame. It reacts only sluggishly with some reagents, like [[iodine]] to form [[samarium(III) iodide]].
−
As a lanthanide, samarium is quite reactive, but its corrosion resistance is between that of the light and heavy rare earth metals. Exposure to air will eventually turn it to a white powdery oxide, but it is nowhere near as reactive as europium or [[lanthanum]]. It burns in air to from yellowish [[samarium(III) oxide]] in a bright red flame. It reacts only sluggishly with [[iodine]] to form [[samarium(III) iodide]].
+
  
−
Samarium is notable for the existence of a dipositive ion, samarium(II), which is a strong reducing agent, as the tripositive ion is more stable. Its most common form, [[samarium(II) iodide]], will reduce water and acids to [[hydrogen]], and is an effective one-electron reductor for organic synthesis (the Barbier reaction is its most notable use). Its dramatic color change from nearly black to pale yellow in [[Tetrahydrofuran|THF]] makes it an excellent redox indicator as well. The dipositive ion, which forms a blood-red to mauve coloration, has occasionally been observed when samarium metal is placed in [[hydrochloric acid]], though it appears to be quickly oxidized upon production.
+
Samarium is notable for the existence of a dipositive ion, samarium(II), which is a strong reducing agent, as the tripositive ion is more stable. Its most common form, [[samarium(II) iodide]], will reduce water and acids to [[hydrogen]], and is an effective one-electron reductor for organic synthesis (the Barbier reaction is its most notable use, and it's well known for catalyzing the [[pinacol coupling reaction]]). Its dramatic color change from nearly black to pale yellow in [[Tetrahydrofuran|THF]] makes it an excellent redox indicator as well. The dipositive ion, which forms a blood-red to mauve coloration, has occasionally been observed when samarium metal is placed in [[hydrochloric acid]], though it appears to be quickly oxidized upon production. A standard laboratory prep for the compound is addition of the metal to a solution of [[1,2-diiodoethane]] in [[tetrahydrofuran]].
  
 
==Availability and preparation==
 
==Availability and preparation==
Line 15: Line 286:
  
 
==Projects==
 
==Projects==
 +
*Make Sm compounds
 
*Red pyrotechnic mixtures
 
*Red pyrotechnic mixtures
 
*Reductions with samarium(II) iodide
 
*Reductions with samarium(II) iodide
 
*Dissolving samarium in liquid [[ammonia]] to produce [[solvated electrons]]
 
*Dissolving samarium in liquid [[ammonia]] to produce [[solvated electrons]]
 +
 
===The mysteries of samarium(II)===
 
===The mysteries of samarium(II)===
 
Work has been done on the stability of the samarium(II) ion in aqueous solution, but research is incomplete. It is also unknown how to coax samarium to react with iodine, as the reaction is very sluggish.
 
Work has been done on the stability of the samarium(II) ion in aqueous solution, but research is incomplete. It is also unknown how to coax samarium to react with iodine, as the reaction is very sluggish.
 +
 
==Safety==
 
==Safety==
 
===Storage===
 
===Storage===
 
Samarium metal tends to corrode, so sealing it in an airtight container is recommended. Mineral oil also helps with preservation of the metal. Samarium does not corrode as fast as europium, [[calcium]], or [[sodium]], so taking it out in air for a few minutes at a time will not affect the sample.
 
Samarium metal tends to corrode, so sealing it in an airtight container is recommended. Mineral oil also helps with preservation of the metal. Samarium does not corrode as fast as europium, [[calcium]], or [[sodium]], so taking it out in air for a few minutes at a time will not affect the sample.
 +
 
===Toxicity===
 
===Toxicity===
 
Samarium compounds have not been investigated for their toxicity, and should be treated as mildly toxic. Salts of samarium, especially the halides, tend to hydrolyze at elevated temperatures and may emit noxious or strongly acidic vapors.
 
Samarium compounds have not been investigated for their toxicity, and should be treated as mildly toxic. Salts of samarium, especially the halides, tend to hydrolyze at elevated temperatures and may emit noxious or strongly acidic vapors.
 +
 
===Flammability===
 
===Flammability===
 
Samarium as small pieces will ignite in the presence of an open flame, and samarium dust and powder may ignite spontaneously in air. Samarium and europium fires can be identified due to their bright red flames. Class D [http://sciencemadness.wikia.com/wiki/Fire_extinguisher?veaction=edit&redlink=1 fire extingushers] should be at hand. Water may aggravate burning samarium and should never be used.
 
Samarium as small pieces will ignite in the presence of an open flame, and samarium dust and powder may ignite spontaneously in air. Samarium and europium fires can be identified due to their bright red flames. Class D [http://sciencemadness.wikia.com/wiki/Fire_extinguisher?veaction=edit&redlink=1 fire extingushers] should be at hand. Water may aggravate burning samarium and should never be used.
 +
 +
==Gallery==
 +
<gallery widths="200" position="center" columns="4" orientation="none">
 +
Samarium_tree_by_diddi.png|A truly massive 750g chunk of samarium owned by diddi.
 +
Samarium iodine by blogfast25.jpg|Samarium after being heated with iodine. Photo by blogfast25.
 +
</gallery>
  
 
==References==
 
==References==
 
<references/>
 
<references/>
 
===Relevant Sciencemadness threads===
 
===Relevant Sciencemadness threads===
 +
*[https://www.sciencemadness.org/whisper/viewthread.php?tid=17986 Samarium from SmCo5 Magnets]
 +
 +
[[Category:Elements]]
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[[Category:Metals]]
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[[Category:Rare earth metals]]
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[[Category:Lanthanides]]
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[[Category:Reducing agents]]
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[[Category:Materials that react with water]]
 +
[[Category:Materials unstable in acidic solution]]
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[[Category:Air-sensitive materials]]
 +
[[Category:F-block]]

Latest revision as of 20:36, 26 December 2022

Samarium,  62Sm
Samarium shards 4k.jpg
Samarium metal
General properties
Name, symbol Samarium, Sm
Appearance Silvery gray
Samarium in the periodic table
-
↑
Sm
↓
Pu
Promethium ← Samarium → Europium
Atomic number 62
Standard atomic weight (Ar) 150.36(2)
Group, block n/a; f-block
Period period 6
Electron configuration [Xe] 4f6 6s2
per shell
 2, 8, 18, 24, 8, 2
Physical properties
Silvery-gray
Phase Solid
Melting point 1345 K ​(1072 °C, ​​1962 °F)
Boiling point 2173 K ​(1900 °C, ​​3452 °F)
Density near r.t. 7.52 g/cm3
when liquid, at  7.16 g/cm3
Heat of fusion 8.62 kJ/mol
Heat of 192 kJ/mol
Molar heat capacity 29.54 J/(mol·K)
 pressure
Atomic properties
Oxidation states 4, 3, 2, 1 ​(a mildly basic oxide)
Electronegativity Pauling scale: 1.17
energies 1st: 544.5 kJ/mol
2nd: 1070 kJ/mol
3rd: 2260 kJ/mol
Atomic radius empirical: 180 pm
Covalent radius 198±8 pm
Miscellanea
Crystal structure ​Rhombohedral
Speed of sound thin rod 2130 m/s (at 20 °C)
Thermal expansion 12.7 µm/(m·K) (α, poly)
Thermal conductivity 13.3 W/(m·K)
Electrical resistivity 9.4·10-7 Ω·m (α, poly)
Magnetic ordering Paramagnetic
Young's modulus 49.7 GPa (α form)
Shear modulus 19.5 GPa (α form)
Bulk modulus 37.8 GPa (α form)
Poisson ratio 0.274 (α form)
Vickers hardness 410–440 MPa
Brinell hardness 440–600 MPa
CAS Registry Number 7440-19-9
History
Naming After the mineral samarskite (itself named after Vassili Samarsky-Bykhovets)
Discovery and first isolation Lecoq de Boisbaudran (1879)
· references

Samarium is a lanthanide with the symbol Sm and atomic number 62. It is a grayish-silvery metal, with similar reactivity to magnesium. Its chemical behavior is similar to most other rare earth metals, but it is notable for the presence of a blood-red samarium (II) ion in reducing conditions.

Properties

Physical properties

Samarium is a grayish metal that is about as dense as iron or manganese. Freshly cut pieces are very shiny and lustrous, while older ones are generally darker from a thin oxide layer. It is very slightly paramagnetic - more so than vanadium, but less than europium, and can be very easily demonstrated by placing a piece on a styrofoam block on water and pulling it with a neodymium magnet.

Chemical properties

As a lanthanide, samarium is quite reactive, but its corrosion resistance is between that of the light and heavy rare earth metals. Exposure to air will eventually turn it to a white powdery oxide, but it is nowhere near as reactive as europium or lanthanum. It burns in air to from yellowish samarium(III) oxide in a bright red flame. It reacts only sluggishly with some reagents, like iodine to form samarium(III) iodide.

Samarium is notable for the existence of a dipositive ion, samarium(II), which is a strong reducing agent, as the tripositive ion is more stable. Its most common form, samarium(II) iodide, will reduce water and acids to hydrogen, and is an effective one-electron reductor for organic synthesis (the Barbier reaction is its most notable use, and it's well known for catalyzing the pinacol coupling reaction). Its dramatic color change from nearly black to pale yellow in THF makes it an excellent redox indicator as well. The dipositive ion, which forms a blood-red to mauve coloration, has occasionally been observed when samarium metal is placed in hydrochloric acid, though it appears to be quickly oxidized upon production. A standard laboratory prep for the compound is addition of the metal to a solution of 1,2-diiodoethane in tetrahydrofuran.

Availability and preparation

Samarium is more common than iodine on Earth, but it is hard to find and expensive. It is, however, one of the cheapest lanthanides, along with gadolinium. One source for samarium, as well as other rare earth metals, is Metallium. It is sold in 5 and 40 gram sizes, as well as rods, ampoules, and coins. Samarium metal is sold in even larger amounts on eBay, but Metallium also takes custom orders of turnings, large cast ingots, and powders. Samarium(III) oxide is relatively cheap among rare-earth compounds, and can be reduced to samarium metal with lanthanum powder in a thermite-like reaction. The most common way to extract elemental samarium, however, is the electrolysis of molten anhydrous samarium(III) chloride.

Projects

  • Make Sm compounds
  • Red pyrotechnic mixtures
  • Reductions with samarium(II) iodide
  • Dissolving samarium in liquid ammonia to produce solvated electrons

The mysteries of samarium(II)

Work has been done on the stability of the samarium(II) ion in aqueous solution, but research is incomplete. It is also unknown how to coax samarium to react with iodine, as the reaction is very sluggish.

Safety

Storage

Samarium metal tends to corrode, so sealing it in an airtight container is recommended. Mineral oil also helps with preservation of the metal. Samarium does not corrode as fast as europium, calcium, or sodium, so taking it out in air for a few minutes at a time will not affect the sample.

Toxicity

Samarium compounds have not been investigated for their toxicity, and should be treated as mildly toxic. Salts of samarium, especially the halides, tend to hydrolyze at elevated temperatures and may emit noxious or strongly acidic vapors.

Flammability

Samarium as small pieces will ignite in the presence of an open flame, and samarium dust and powder may ignite spontaneously in air. Samarium and europium fires can be identified due to their bright red flames. Class D fire extingushers should be at hand. Water may aggravate burning samarium and should never be used.

Gallery

  • A truly massive 750g chunk of samarium owned by diddi.

  • Samarium after being heated with iodine. Photo by blogfast25.

References

Relevant Sciencemadness threads

Retrieved from "https://www.sciencemadness.org/smwiki/index.php?title=Samarium&oldid=14873"