Difference between revisions of "Gallium"

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'''Gallium''' is a chemical element with symbol Ga and atomic number 31.
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{{Infobox element
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<!-- General properties -->
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|name=Gallium
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|symbol=Ga
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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=[[Aluminium|Al]]
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|below=[[Indium|In]]
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|left=[[Zinc]]
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|right=[[Germanium]]
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|number=31
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|atomic mass=69.723(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 ref=
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|series comment=
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|series color=
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|group= 13
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|group ref=
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|group comment=(boron group)
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|period=4
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|period ref=
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|period comment=
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|block=p
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|block ref=
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|block comment=
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|electron configuration=[Ar] 3d<sup>10</sup> 4s<sup>2</sup> 4p<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, 3
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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=302.9146
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|melting point C=29.7646
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|melting point F=85.5763
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|melting point ref=
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|melting point comment=
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|boiling point K=2673
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|boiling point C=2400
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|boiling point F=​4352
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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=5.91
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|density gpcm3nrt ref=
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|density gpcm3nrt 3=
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|density gpcm3nrt 3 comment=
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|density gpcm3mp=6.095
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|density gpcm3mp ref=
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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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|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=5.59
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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=256
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|heat vaporization ref=
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|heat vaporization comment=
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|heat capacity=25.86
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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=1310
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|vapor pressure 10=1448
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|vapor pressure 100=1620
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|vapor pressure 1 k=1838
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|vapor pressure 10 k=2125
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|vapor pressure 100 k=2518
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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='''3''', 2, 1, −1, −2, −4, −5
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|oxidation states ref=​(an amphoteric oxide)
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|oxidation states comment=
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|electronegativity=1.81
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|electronegativity ref=
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|electronegativity comment=
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|ionization energy 1=578.8
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|ionization energy 1 ref=
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|ionization energy 1 comment=
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|ionization energy 2=1979.3
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|ionization energy 2 ref=
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|ionization energy 2 comment=
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|ionization energy 3=2963
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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=135
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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=122±3
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|covalent radius ref=
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|covalent radius comment=
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|Van der Waals radius=187
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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=Orthorhombic
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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=2740
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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=18
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|thermal expansion at 25 ref=
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|thermal expansion at 25 comment=
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|thermal conductivity=40.6
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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 diffusivity=
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|electrical resistivity=
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|electrical resistivity at 0=
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|electrical resistivity at 0 comment=
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|electrical resistivity at 20=2.7·10<sup>-7</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=Diamagnetic
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|magnetic ordering ref=
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|magnetic ordering comment=
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|tensile strength=
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|tensile strength ref=
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|tensile strength comment=
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|Young's modulus=9.8
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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=
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|Bulk modulus ref=
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|Bulk modulus comment=
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|Poisson ratio=0.47
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|Poisson ratio ref=
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|Poisson ratio comment=
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|Mohs hardness=1.5
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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 comment=
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|Brinell hardness=56.8–68.7
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|Brinell hardness ref=
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|Brinell hardness comment=
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|CAS number=7440-55-3
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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 Gallia (Latin for: France), homeland of the discoverer
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|predicted by= Dmitri Mendeleev
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|prediction date ref=
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|prediction date=1871
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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 (1875)
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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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'''Gallium''' is a chemical element with symbol '''Ga''' and atomic number 31.
  
 
==Properties==
 
==Properties==

Revision as of 20:27, 15 October 2017

Gallium,  31Ga
General properties
Name, symbol Gallium, Ga
Appearance Silvery white
Gallium in the periodic table
Al
↑
Ga
↓
In
Zinc ← Gallium → Germanium
Atomic number 31
Standard atomic weight (Ar) 69.723(1)
Group, block (boron group); p-block
Period period 4
Electron configuration [Ar] 3d10 4s2 4p1
per shell
 2, 8, 18, 3
Physical properties
Silvery-white
Phase Solid
Melting point 302.9146 K ​(29.7646 °C, ​85.5763 °F)
Boiling point 2673 K ​(2400 °C, ​​4352 °F)
Density near r.t. 5.91 g/cm3
when liquid, at  6.095 g/cm3
Heat of fusion 5.59 kJ/mol
Heat of 256 kJ/mol
Molar heat capacity 25.86 J/(mol·K)
 pressure
Atomic properties
Oxidation states 3, 2, 1, −1, −2, −4, −5​(an amphoteric oxide)
Electronegativity Pauling scale: 1.81
energies 1st: 578.8 kJ/mol
2nd: 1979.3 kJ/mol
3rd: 2963 kJ/mol
Atomic radius empirical: 135 pm
Covalent radius 122±3 pm
Van der Waals radius 187 pm
Miscellanea
Crystal structure ​Orthorhombic
Speed of sound thin rod 2740 m/s (at 20 °C)
Thermal expansion 18 µm/(m·K) (at 25 °C)
Thermal conductivity 40.6 W/(m·K)
Electrical resistivity 2.7·10-7 Ω·m (at 20 °C)
Magnetic ordering Diamagnetic
Young's modulus 9.8 GPa
Poisson ratio 0.47
Mohs hardness 1.5
Brinell hardness 56.8–68.7 MPa
CAS Registry Number 7440-55-3
History
Naming After Gallia (Latin for: France), homeland of the discoverer
Prediction Dmitri Mendeleev (1871)
Discovery and first isolation Lecoq de Boisbaudran (1875)
· references

Gallium is a chemical element with symbol Ga and atomic number 31.

Properties

Chemical

Gallium is attacked by acids and free halogens, but does not react with air or water at room temperature, only at high temperatures, producing gallium(III) oxide Ga2O3. If Ga2O3 is reduced with elemental gallium in vacuum at 500-700 °C, it will yield the dark brown gallium(I) oxide, Ga2O.

Ga2O3 + 4 Ga → 3 Ga2O

Gallium(I) oxide is a strong reducing agent, capable of reducing sulfuric acid to hydrogen sulfide.

Gallium attacks most other metals by diffusing into their metal lattice. Aluminium is highly susceptible, as well as zinc, aluminium-zinc alloys, certain steel grades[1], making them very brittle.

Physical

Gallium is a soft silvery metal, brittle at low temperatures. If it is held in the human hand long enough, gallium will melt, since its melting point is 29.76 °C. Gallium expands by 3.1% when it solidifies, and therefore storage in either glass or metal containers should be avoided. Liquid gallium has a strong tendency to supercool below its melting point/freezing point. Unlike mercury, liquid gallium wets glass and skin, making it mechanically more difficult to handle. For this reason, as well as the metal contamination and freezing-expansion problems, samples of gallium metal are usually supplied in polyethylene packets within other containers.

Availability

LED's contain a minute amount of gallium nitride, but the quantity is too small to be of importance. Certain low melting alloys contain gallium.

The best source of metallic gallium is GalliumSource, that sells gallium samples, a 100 g sample costs around 65$, though the price does not include shipping. For international shipping, the price is higher and the shipping is included in the price.

Preparation

Gallium can be prepared by reducing its halides.

Projects

  • Inducing embrittlement in susceptible metals, such as aluminium
  • Gallium nitride synthesis
  • Gallium spoon prank
  • Gallium beating heart
  • Hydrogen generation

Handling

Safety

Pure gallium has little toxicity, but its tendency to wet most materials can be frustrating, so gloves should be worn when handling the pure metal, especially since it will melt in the hand if held too long. Some of its compounds have been shown to cause renal problems in tested animals. Bulk gallium nitride has been shown to be non-toxic and even bio-compatible.[2]

Storage

Because gallium tends to expand when it solidifies, it's best stored in thick polyethylene bottles or if it's a small sample, in top lid boxes.

Disposal

Gallium is best recycled, when possible.

References

  1. ↑ handle.dtic.mil/100.2/ADA365497
  2. ↑ http://news.ncsu.edu/2011/10/wmsivanisevicganpeptides/

Relevant Sciencemadness threads

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