Difference between revisions of "Phosphorus"

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[[File:Phosphorus main allotropes.jpg|thumb|400px|White, red powder, red chunk and violet phosphorus. (left to right.)]]
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{{Infobox element
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|image name=Phosphorus main allotropes.jpg
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|image alt=
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|image size=295
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|image name comment=White, red powder, red chunk and violet phosphorus (left to right).
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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=Phosphorus
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|symbol=P
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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=White, red, violet, black
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|appearance=Colorless or waxy white, yellow, scarlet, red, violet, black
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<!-- Periodic table -->
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|above=[[Nitrogen|N]]
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|below=[[Arsenic|As]]
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|left=[[Silicon]]
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|right=[[Sulfur]]
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|number=15
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|atomic mass=30.973761998(5)
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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=15
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|group ref=
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|group comment=
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|period=3
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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=[Ne] 3s<sup>2</sup> 3p<sup>3</sup>
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|electron configuration ref=
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|electron configuration comment=
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|electrons per shell=2, 8, 5
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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=White, yellow, scarlet, red, violet, black
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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=317.25
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|melting point C=44.1
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|melting point F=111.38
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|melting point ref=
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|melting point comment=(white)<br>883.15-898.15 K (610-625 °C; 1130-1157 °F) (red)
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|boiling point K=553.15
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|boiling point C=280
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|boiling point F=536
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|boiling point ref=
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|boiling point comment=(white)
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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=1.823
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|density gpcm3nrt ref=
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|density gpcm3nrt comment=(white)
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|density gpcm3nrt 2=2.2–2.34
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|density gpcm3nrt 2 ref=
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|density gpcm3nrt 2 comment=(red)
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|density gpcm3nrt 3=2.36
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|density gpcm3nrt 3 ref=
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|density gpcm3nrt 3 comment=(violet)
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|density gpcm3nrt 4=2.69
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|density gpcm3nrt 4 ref=
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|density gpcm3nrt 4 comment=(black)
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|density gpcm3mp=
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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=0.66
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|heat fusion ref=
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|heat fusion comment=(white)
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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=51.9
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|heat vaporization ref=
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|heat vaporization comment=(white)
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|heat capacity=23.824
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|heat capacity ref=
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|heat capacity comment=(white)
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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=279
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|vapor pressure 10=307
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|vapor pressure 100=342
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|vapor pressure 1 k=388
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|vapor pressure 10 k=453
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|vapor pressure 100 k=549
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|vapor pressure ref=
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|vapor pressure comment=(white)
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|vapor pressure 1 2=455
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|vapor pressure 10 2=489
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|vapor pressure 100 2=529
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|vapor pressure 1 k 2=576
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|vapor pressure 10 k 2=635
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|vapor pressure 100 k 2=704
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|vapor pressure 2 ref=
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|vapor pressure 2 comment=(red)
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<!-- Atomic properties -->
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|atomic properties comment=
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|oxidation states= '''5''', 4, '''3''', 2, 1, −1, −2, '''−3'''
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|oxidation states ref=
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|oxidation states comment=(a mildly acidic oxide)
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|electronegativity=2.19
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|electronegativity ref=
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|electronegativity comment=
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|ionization energy 1=1011.8
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|ionization energy 1 ref=
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|ionization energy 1 comment=
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|ionization energy 2=1907
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|ionization energy 2 ref=
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|ionization energy 2 comment=
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|ionization energy 3=2914.1
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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=
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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=107±3
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|covalent radius ref=
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|covalent radius comment=
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|Van der Waals radius=180
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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=
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|thermal expansion at 25 ref=
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|thermal expansion at 25 comment=
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|thermal conductivity=0.236
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|thermal conductivity ref=
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|thermal conductivity comment=(white)
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|thermal conductivity 2=12.1
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|thermal conductivity 2 ref=
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|thermal conductivity 2 comment=(black)
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|thermal diffusivity=
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|thermal diffusivity ref=
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|thermal diffusivity comment=
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|electrical resistivity=
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|electrical resistivity unit prefix=
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|electrical resistivity ref=
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|electrical resistivity comment=
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|electrical resistivity at 0=
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|electrical resistivity at 0 ref=
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|electrical resistivity at 0 comment=
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|electrical resistivity at 20=
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|electrical resistivity at 20 ref=
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|electrical resistivity at 20 comment=
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|band gap=
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|band gap ref=
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|band gap comment=
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|Curie point K=
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|Curie point ref=
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|Curie point comment=
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|magnetic ordering=Diamagnetic
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|magnetic ordering ref=
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|magnetic ordering comment=(white, red, violet, black)
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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=
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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=white: 5 GPa<br>red: 11 GPa
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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=
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|Mohs hardness ref=
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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=
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|Brinell hardness ref=
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|Brinell hardness comment=
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|CAS number=7723-14-0 (red)<br>12185-10-3 (white)
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|CAS number ref=
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|CAS number comment=
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<!-- History -->
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|naming=
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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= Hennig Brand
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|discovery date ref=
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|discovery date=1669
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|first isolation by=
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|first isolation date=
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|discovery and first isolation by=
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|named by=
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|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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}}
 
'''Phosphorus''' is a chemical element with symbol '''P''' and atomic number 15. It is a solid nonmetal, consisting of two main allotrope forms, white and red. The white form is highly reactive in the atmosphere, while the other forms of phosphorus much less.
 
'''Phosphorus''' is a chemical element with symbol '''P''' and atomic number 15. It is a solid nonmetal, consisting of two main allotrope forms, white and red. The white form is highly reactive in the atmosphere, while the other forms of phosphorus much less.
  
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White phosphorus reacts with air and can spontaneously ignite, if heated slightly, forming [[phosphorus pentoxide]]. Red phosphorus is much more stable in air, but will react with halogens.
 
White phosphorus reacts with air and can spontaneously ignite, if heated slightly, forming [[phosphorus pentoxide]]. Red phosphorus is much more stable in air, but will react with halogens.
  
Phosphorus chloride, for example, is formed from the reaction of white phosphorus and chlorine gas
+
Phosphorus chlorides, for example, are formed from the reaction of white phosphorus and [[chlorine]] gas
  
 
:P<sub>4</sub> + 6 Cl<sub>2</sub> → 4 PCl<sub>3</sub>
 
:P<sub>4</sub> + 6 Cl<sub>2</sub> → 4 PCl<sub>3</sub>
  
White phosphorus will react with nitric acid to produce [[phosphoric acid]] and nitrogen dioxide.
+
White phosphorus will react with nitric acid to produce [[phosphoric acid]] and [[nitrogen dioxide]].
  
 
:P + 5 HNO<sub>3</sub> → H<sub>2</sub>O + H<sub>3</sub>PO<sub>4</sub> + 5 NO<sub>2</sub>
 
:P + 5 HNO<sub>3</sub> → H<sub>2</sub>O + H<sub>3</sub>PO<sub>4</sub> + 5 NO<sub>2</sub>
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===Physical===
 
===Physical===
 
Phosphorus is solid at standard conditions and exhibits several [[allotrope]] forms:
 
Phosphorus is solid at standard conditions and exhibits several [[allotrope]] forms:
*'''White phosphorus''' - also known as '''yellow phosphorus''', '''WP '''or simply '''tetraphosphorus''' (P<sub>4</sub>) is a white waxy solid, that becomes yellow when exposed to light. When exposed to oxygen, it glows green in the dark, is extremely flammable and pyrophoric upon contact with air, and is very toxic, having the potential to cause morbidity and death through high enough exposures. It is almost always stored underwater to prevent ignition. White phosphorus is highly soluble in [[carbon disulfide]] and [[disulfur dichloride]], somewhat soluble in [[chloroform]] and [[benzene]], and slightly soluble in [[diethyl ether]]. Evaporation of these solutions yields scarlet-colored phosphorus.
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*'''White phosphorus''' - also known as '''yellow phosphorus''', '''WP '''or simply '''tetraphosphorus''' (P<sub>4</sub>) is a white waxy solid, that becomes yellow when exposed to light. When exposed to oxygen, it glows green in the dark, is extremely flammable and pyrophoric upon contact with air, and is very toxic, having the potential to cause morbidity and death through high enough exposures. It is almost always stored underwater to prevent ignition. White phosphorus is highly soluble in [[carbon disulfide]] and [[disulfur dichloride]], soluble in anh. [[ammonia]], [[ethanol]], [[thionyl chloride]], [[toluene]], somewhat soluble in [[benzene]] and [[chloroform]], and slightly soluble in [[acetone]], [[carbon tetrachloride]], [[diethyl ether]], [[heptane]], [[mineral oil|paraffin]], anh. [[phosphine]]. Evaporation of these solutions yields scarlet-colored phosphorus.
*'''Red phosphorus '''is an amorphous red solid at standard conditions, and is considerably more stable than the white form. It is formed by heating white phosphorus to 250 °C in inert conditions. It is insoluble in all solvents, though it can form a solution with phosphorus tribromide<ref>A Laboratory History of Narcotics, Amphetamines and Derivatives Vol. 1, 2007, Jared Ledgard, p. 65. </ref>.
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*'''Red phosphorus ''' - also called '''red P''', is an amorphous red solid at standard conditions, and is considerably more stable than the white form. It is formed by heating white phosphorus to 250 °C in inert conditions. It is insoluble in all solvents, though it may react with some chemicals.
 
*'''Violet phosphorus''' - also known as '''monoclinic phosphorus''', it is solid brown-violet. It is formed by heating red phosphorus in a sealed tube at 530 °C or white phosphorus at 500 °C in molten lead for 18 hours. Insoluble in all solvents, violet phosphorus has low reactivity and ignites in air at 300 °C.
 
*'''Violet phosphorus''' - also known as '''monoclinic phosphorus''', it is solid brown-violet. It is formed by heating red phosphorus in a sealed tube at 530 °C or white phosphorus at 500 °C in molten lead for 18 hours. Insoluble in all solvents, violet phosphorus has low reactivity and ignites in air at 300 °C.
 
*'''Black phosphorus''' - it is thermodynamically stable at standard conditions. The black form is obtained by heating white phosphorus under incredibly high pressures (12,000 atmospheres). It is similar to graphite in appearance and properties, as a flaky black solid that conducts electricity. It is the least reactive allotrope form.
 
*'''Black phosphorus''' - it is thermodynamically stable at standard conditions. The black form is obtained by heating white phosphorus under incredibly high pressures (12,000 atmospheres). It is similar to graphite in appearance and properties, as a flaky black solid that conducts electricity. It is the least reactive allotrope form.
 
*'''Diphosphorus''' - Unlike the other forms, it is gaseous. Diphosphorus can be obtained normally only under extreme conditions (from P<sub>4</sub> at 1100 K). Is is only stable between 1200 °C - 2000 °C.
 
*'''Diphosphorus''' - Unlike the other forms, it is gaseous. Diphosphorus can be obtained normally only under extreme conditions (from P<sub>4</sub> at 1100 K). Is is only stable between 1200 °C - 2000 °C.
  
Only the first two forms are of importance.
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Only the first two forms are of importance to chemists, while violet and black phosphorus are mostly sought for [[element collecting|element collection]], due to their rarity.
  
 
White phosphorus is soluble in many organic solvents, whereas the other varieties are insoluble in any solvent.
 
White phosphorus is soluble in many organic solvents, whereas the other varieties are insoluble in any solvent.
  
 
==Availability==
 
==Availability==
In the US, the sale of red and white phosphorus is restricted, as it can reduce elemental [[iodine]] to [[hydroiodic acid]], which is a reagent effective for reducing ephedrine or pseudoephedrine to methamphetamine. It is classified as List I precursor chemicals under 21 CFR 1310.02 by the DEA.
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Red phosphorus can be extracted from the striker strips found on match boxes, that consist of red phosphorus, ground glass and glue. The strips are soaked with [[acetone]] to remove the glue, then scraped from the sides. However, there are some types of striker strips that use a very strong adhesive which cannot be dissolved with acetone, and instead [[chloroform]] or [[dichloromethane]] should be used. As the scraped paste also contains ground glass and other impurities, purification is required. Red phosphorus is not soluble in any solvents, so the purification is a bit more complicated. One way to remove the glass is to add a solution of sodium hydroxide to dissolve the glass, although this will take some time. The resulting RP is filtered, collected and dried. This method however requires a large number of striker strips: a typical matchbox has between 0.005-0.05 g RP, depending on the type of matchbox, thus it takes around 200 matchboxes to obtain 1 g of RP). However, matchboxes with full surface striker strips have much more red P, in the case of large matchboxes, you may even get 0.1 g per striker strip.<ref>http://williestop.tripod.com/generalchemdata/redphosphorus.html</ref> It is much more efficient in the long run to invest in making your own phosphorus-producing apparatus to make white phosphorus. Buying huge amounts of matches is also likely to be noticed and attract attention, as it is something often done by drug manufacturers.
 
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Red phosphorus can be extracted from the striker strips found on match boxes, that consist of red phosphorus, ground glass and glue. The strips are soaked with [[acetone]] to remove the glue, then scraped from the sides. As the scraped paste also contains ground glass and other impurities, purification is required. Red phosphorus is not soluble in any solvents, so the purification is a bit more complicated. One way to remove the glass is to add a solution of sodium hydroxide to dissolve the glass, although this will take some time. The resulting RP is filtered, collected and dried. This method however requires a large number of striker strips (a typical matchbox has around 0.005g RP, thus it takes around 200 matchboxes to obtain 1 g of RP).<ref>http://williestop.tripod.com/generalchemdata/redphosphorus.html</ref>It is much more efficient in the long run to invest in making your own phosphorus-producing apparatus to make white phosphorus. Buying huge amounts of matches is also likely to be noticed and attract attention, as it is something often done by drug manufacturers.
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===Legality===
 
===Legality===
Phosphorus of any kind, especially red phosphorus, is highly restricted in the United States, where it is a DEA List I chemical. As such, phosphorus is illegal to distribute and those that possess any are highly suspect for illicit drug manufacture.
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==== United States ====
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In the US, the sale of red and white phosphorus is restricted, as it can reduce elemental [[iodine]] to [[hydroiodic acid]], which is a reagent effective for reducing ephedrine or pseudoephedrine to methamphetamine. It is classified as List I precursor chemicals under 21 CFR 1310.02 by the DEA.
  
 
==Preparation==
 
==Preparation==
Elemental phosphorus is difficult to prepare by the home chemist, because extracting it requires very high temperatures. A mixture of [[calcium phosphate]], [[silicon dioxide]] and [[carbon]] reacts at 1500 °C to form calcium silicate, carbon monoxide and white phosphorus:
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===White phosphorus===
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Elemental phosphorus is difficult, but not impossible to prepare by the home chemist, because extracting it requires very high temperatures. A mixture of [[calcium phosphate]], [[silicon dioxide]] and [[carbon]] reacts at 1500 °C to form calcium silicate, carbon monoxide and white phosphorus:
  
 
:2 Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> + 6 SiO<sub>2</sub> + 10 C → 6 CaSiO<sub>3</sub> + 10 CO + P<sub>4</sub>
 
:2 Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> + 6 SiO<sub>2</sub> + 10 C → 6 CaSiO<sub>3</sub> + 10 CO + P<sub>4</sub>
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:3 Na<sub>3</sub>PO<sub>4</sub> + 5 Al + 2 SiO<sub>2</sub> → 3/4 P<sub>4</sub> + 5 NaAlO<sub>2</sub> + 2 Na<sub>2</sub>SiO<sub>3</sub>
 
:3 Na<sub>3</sub>PO<sub>4</sub> + 5 Al + 2 SiO<sub>2</sub> → 3/4 P<sub>4</sub> + 5 NaAlO<sub>2</sub> + 2 Na<sub>2</sub>SiO<sub>3</sub>
 +
 +
Various sources of phosphates can be used as starting material. [[Sodium hexametaphosphate]] is also used due to its high percentage of phoshporus.
 +
 +
: (NaPO<sub>3</sub>)<sub>6</sub> + 10 Al + 3 SiO<sub>2</sub> → 3/2 P<sub>4</sub> + Al<sub>2</sub>O<sub>3</sub> + 3 Na<sub>2</sub>SiO<sub>3</sub> Na<sub>2</sub>SiO<sub>3</sub>
  
 
A less thermal method involves the reaction of calcium phosphate with [[sulfuric acid]], which produces [[phosphoric acid]]. This is reduced with carbon and the phosphorus vapors are condensed underwater.
 
A less thermal method involves the reaction of calcium phosphate with [[sulfuric acid]], which produces [[phosphoric acid]]. This is reduced with carbon and the phosphorus vapors are condensed underwater.
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Another method would require the thermal decomposition of copper phosphide:
 
Another method would require the thermal decomposition of copper phosphide:
:4Cu<sub>3</sub>P<sub>2</sub> → 4Cu<sub>3</sub>P + P<sub>4</sub>
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 +
: 4 Cu<sub>3</sub>P<sub>2</sub> → 4 Cu<sub>3</sub>P + P<sub>4</sub>
 +
 
 
The copper phosphide can be obtained by reducing [[copper(II) phosphate]] with a metal, (aluminium e.g.).
 
The copper phosphide can be obtained by reducing [[copper(II) phosphate]] with a metal, (aluminium e.g.).
  
The final product of all these methods produce the white form, so the condensation of the phosphorus must be done underwater.
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The the phosphorus obtained from all these methods is the gaseous diphosphorus form which, upon condensation, gives the white form, so the condensation of the raw phosphorus must be done underwater. Very little red P if any is produced during these routes.
 +
 
 +
===Red phosphorus===
 +
To obtain red P, white phosphorus is placed in a thick stainless steel retort, with potassium iodide being added as a catalyst. The retort is heated to 250 °C for several hours, which results in impure red P, with plenty of unreacted white P. Upon opening, contact with air may cause the white P to catch fire, so it's best to open the container underwater.<ref>https://www.youtube.com/watch?v=Cqn2szaTOUQ</ref>
 +
 
 +
To safely remove the white P from the mixture, an organic solvent, like toluene or carbon disulfide is added to dissolve it. Decant the liquid and use a separatory funnel to separate the aqueous layer from the hazardous organic layer. Remove any large impurities by hand or with tweezers and finely grind the red P into a powder to see if there are any impurities left in the hardened blocks.
  
 
==Projects==
 
==Projects==
 
*Fenian fire and [[KS Fluid]] (WP solution self-ignition via evaporation of solvent)
 
*Fenian fire and [[KS Fluid]] (WP solution self-ignition via evaporation of solvent)
 
*Metal phosphides
 
*Metal phosphides
*[[Phosphorus pentachloride]] synthesis
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*Synthesis of phosphorus halides, like [[phosphorus trichloride]], [[phosphorus pentachloride]], [[phosphorus tribromide]], [[phosphorus triiodide]]
  
 
==Handling==
 
==Handling==
 
===Safety===
 
===Safety===
The white phosphorus allotrope presents a significant hazard because it's pyrophoric and produces phosphorus pentoxide and phosphoric acid fumes as residue, that are potent irritants. Chronic white phosphorus poisoning leads to necrosis of the jaw called "phossy jaw". Ingestion of white phosphorus may cause a medical condition known as "Smoking Stool Syndrome" (no, it is not a joke name, it refers to fuming feces, not smoldering furniture).
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The white phosphorus allotrope presents a significant hazard because it's pyrophoric and produces [[phosphorus pentoxide]] and [[phosphoric acid]] fumes as residue, that are potent irritants. Chronic white phosphorus poisoning leads to necrosis of the jaw called "phossy jaw". Ingestion of white phosphorus may cause a medical condition known as "Smoking Stool Syndrome". White phosphorus also has some neurotoxic properties.
  
Certain combinations of phosphorus with halides are extremely toxic. Organophosphate compounds are known nerve toxins as are its precursors. White phosphorus itself has some neurotoxic properties.
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Make sure you never add white phosphorus in a sodium or potassium hydroxide solution, as it will release the toxic [[phosphine]] gas.<ref>Rose, H.; Annalen der Physik (Weinheim, Germany); vol. 6; (1826); p. 199 - 214</ref>
  
Make sure you never add white phosphorus in a sodium or potassium hydroxide solution, as it will release the toxic phosphine gas.<ref>Rose, H.; Annalen der Physik (Weinheim, Germany); vol. 6; (1826); p. 199 - 214</ref>
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Certain combinations of phosphorus with halides are extremely toxic.  
 +
 
 +
Many organophosphate compounds are known nerve toxins as are its precursors.
  
 
===Storage===
 
===Storage===
White phosphorus should be stored in an inert atmosphere, underwater is best. The other type of phosphorus do not require special storage, and can be safely stored in open air.
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White phosphorus should be stored in an inert atmosphere, underwater is best, and in dark, to prevent it from turning into red P. The other types of phosphorus do not require special storage, and can be safely stored in ordinary plastic or glass bottles.
  
 
===Disposal===
 
===Disposal===
White phosphorus should be converted to phosphate ions, which are far less hazardous and can be safely disposed of.
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White phosphorus should be converted to phosphate ions, which are far less hazardous and can be safely disposed of, via different means, depending on the allotrope.  
 +
 
 +
White phosphorus can be neutralized using a 1 M aqueous solution of [[copper(II) sulfate]], using a 100% excess. Bleach can be used to neutralize any leftover phosphides, to prevent the formation of [[phosphine]] gas.
 +
 
 +
: 2 P + 5 Cu<sup>2+</sup> + 8 H<sub>2</sub>O → 2 H<sub>3</sub>PO<sub>4</sub> + 5 Cu + 10 H<sup>+</sup>
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Red phosphorus can be neutralized using an aqueous solution of [[potassium chlorate]]:<ref>[https://pdfs.semanticscholar.org/6ab2/05dda8f781363d79a30ec531728a46d212fe.pdf Prudent Practices for Disposal of Chemicals from Laboratories]</ref>
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: 6 P + KClO<sub>3</sub> + 9 H<sub>2</sub>O → 6 H<sub>3</sub>PO<sub>4</sub> + 5 KCl
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==Gallery==
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<gallery widths="200" position="center" columns="4" orientation="none">
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Red_phosphorus.jpg|Sample of red P
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</gallery>
  
 
==References==
 
==References==
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*[http://www.sciencemadness.org/talk/viewthread.php?tid=65 Preparation of elemental phosphorus]
 
*[http://www.sciencemadness.org/talk/viewthread.php?tid=65 Preparation of elemental phosphorus]
 
*[http://www.sciencemadness.org/talk/viewthread.php?tid=10926 Question: Red phosphorus purification]
 
*[http://www.sciencemadness.org/talk/viewthread.php?tid=10926 Question: Red phosphorus purification]
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*[http://www.sciencemadness.org/talk/viewthread.php?tid=145122 The Wump Incident]
  
 
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[[Category:Elements]]
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[[Category:Things that can kill you very quickly]]
 
[[Category:Things that can kill you very quickly]]
 
[[Category:Contact poisons]]
 
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[[Category:Air-sensitive materials]]
 
[[Category:Pyrophoric materials]]
 
[[Category:Pyrophoric materials]]
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[[Category:DEA List I chemicals]]

Latest revision as of 16:44, 20 June 2019

Phosphorus,  15P
Phosphorus main allotropes.jpg
White, red powder, red chunk and violet phosphorus (left to right).
General properties
Name, symbol Phosphorus, P
Allotropes White, red, violet, black
Appearance Colorless or waxy white, yellow, scarlet, red, violet, black
Phosphorus in the periodic table
N

P

As
SiliconPhosphorusSulfur
Atomic number 15
Standard atomic weight (Ar) 30.973761998(5)
Group, block , p-block
Period period 3
Electron configuration [Ne] 3s2 3p3
per shell
2, 8, 5
Physical properties
White, yellow, scarlet, red, violet, black
Phase Solid
Melting point 317.25 K ​(44.1 °C, ​111.38 °F) (white)
883.15-898.15 K (610-625 °C; 1130-1157 °F) (red)
Boiling point 553.15 K ​(280 °C, ​536 °F) (white)
Density near r.t. 1.823 g/cm3 (white)
2.2–2.34 g/cm3 (red)
2.36 g/cm3 (violet)
Heat of fusion 0.66 kJ/mol (white)
Heat of 51.9 kJ/mol (white)
Molar heat capacity 23.824 J/(mol·K) (white)
 pressure (white)
 pressure (red)
Atomic properties
Oxidation states 5, 4, 3, 2, 1, −1, −2, −3 ​(a mildly acidic oxide)
Electronegativity Pauling scale: 2.19
energies 1st: 1011.8 kJ/mol
2nd: 1907 kJ/mol
3rd: 2914.1 kJ/mol
Covalent radius 107±3 pm
Van der Waals radius 180 pm
Miscellanea
Crystal structure ​Body-centred cubic (bcc)
Thermal conductivity 0.236 W/(m·K) (white)
12.1 W/(m·K) (black)
Magnetic ordering Diamagnetic (white, red, violet, black)
CAS Registry Number 7723-14-0 (red)
12185-10-3 (white)
History
Discovery Hennig Brand (1669)
· references

Phosphorus is a chemical element with symbol P and atomic number 15. It is a solid nonmetal, consisting of two main allotrope forms, white and red. The white form is highly reactive in the atmosphere, while the other forms of phosphorus much less.

Properties

Chemical

White phosphorus reacts with air and can spontaneously ignite, if heated slightly, forming phosphorus pentoxide. Red phosphorus is much more stable in air, but will react with halogens.

Phosphorus chlorides, for example, are formed from the reaction of white phosphorus and chlorine gas

P4 + 6 Cl2 → 4 PCl3

White phosphorus will react with nitric acid to produce phosphoric acid and nitrogen dioxide.

P + 5 HNO3 → H2O + H3PO4 + 5 NO2

Physical

Phosphorus is solid at standard conditions and exhibits several allotrope forms:

  • White phosphorus - also known as yellow phosphorus, WP or simply tetraphosphorus (P4) is a white waxy solid, that becomes yellow when exposed to light. When exposed to oxygen, it glows green in the dark, is extremely flammable and pyrophoric upon contact with air, and is very toxic, having the potential to cause morbidity and death through high enough exposures. It is almost always stored underwater to prevent ignition. White phosphorus is highly soluble in carbon disulfide and disulfur dichloride, soluble in anh. ammonia, ethanol, thionyl chloride, toluene, somewhat soluble in benzene and chloroform, and slightly soluble in acetone, carbon tetrachloride, diethyl ether, heptane, paraffin, anh. phosphine. Evaporation of these solutions yields scarlet-colored phosphorus.
  • Red phosphorus - also called red P, is an amorphous red solid at standard conditions, and is considerably more stable than the white form. It is formed by heating white phosphorus to 250 °C in inert conditions. It is insoluble in all solvents, though it may react with some chemicals.
  • Violet phosphorus - also known as monoclinic phosphorus, it is solid brown-violet. It is formed by heating red phosphorus in a sealed tube at 530 °C or white phosphorus at 500 °C in molten lead for 18 hours. Insoluble in all solvents, violet phosphorus has low reactivity and ignites in air at 300 °C.
  • Black phosphorus - it is thermodynamically stable at standard conditions. The black form is obtained by heating white phosphorus under incredibly high pressures (12,000 atmospheres). It is similar to graphite in appearance and properties, as a flaky black solid that conducts electricity. It is the least reactive allotrope form.
  • Diphosphorus - Unlike the other forms, it is gaseous. Diphosphorus can be obtained normally only under extreme conditions (from P4 at 1100 K). Is is only stable between 1200 °C - 2000 °C.

Only the first two forms are of importance to chemists, while violet and black phosphorus are mostly sought for element collection, due to their rarity.

White phosphorus is soluble in many organic solvents, whereas the other varieties are insoluble in any solvent.

Availability

Red phosphorus can be extracted from the striker strips found on match boxes, that consist of red phosphorus, ground glass and glue. The strips are soaked with acetone to remove the glue, then scraped from the sides. However, there are some types of striker strips that use a very strong adhesive which cannot be dissolved with acetone, and instead chloroform or dichloromethane should be used. As the scraped paste also contains ground glass and other impurities, purification is required. Red phosphorus is not soluble in any solvents, so the purification is a bit more complicated. One way to remove the glass is to add a solution of sodium hydroxide to dissolve the glass, although this will take some time. The resulting RP is filtered, collected and dried. This method however requires a large number of striker strips: a typical matchbox has between 0.005-0.05 g RP, depending on the type of matchbox, thus it takes around 200 matchboxes to obtain 1 g of RP). However, matchboxes with full surface striker strips have much more red P, in the case of large matchboxes, you may even get 0.1 g per striker strip.[1] It is much more efficient in the long run to invest in making your own phosphorus-producing apparatus to make white phosphorus. Buying huge amounts of matches is also likely to be noticed and attract attention, as it is something often done by drug manufacturers.

Legality

United States

In the US, the sale of red and white phosphorus is restricted, as it can reduce elemental iodine to hydroiodic acid, which is a reagent effective for reducing ephedrine or pseudoephedrine to methamphetamine. It is classified as List I precursor chemicals under 21 CFR 1310.02 by the DEA.

Preparation

White phosphorus

Elemental phosphorus is difficult, but not impossible to prepare by the home chemist, because extracting it requires very high temperatures. A mixture of calcium phosphate, silicon dioxide and carbon reacts at 1500 °C to form calcium silicate, carbon monoxide and white phosphorus:

2 Ca3(PO4)2 + 6 SiO2 + 10 C → 6 CaSiO3 + 10 CO + P4

By replacing carbon with aluminium, the reaction can occur at lower temperatures:

3 Na3PO4 + 5 Al + 2 SiO2 → 3/4 P4 + 5 NaAlO2 + 2 Na2SiO3

Various sources of phosphates can be used as starting material. Sodium hexametaphosphate is also used due to its high percentage of phoshporus.

(NaPO3)6 + 10 Al + 3 SiO2 → 3/2 P4 + Al2O3 + 3 Na2SiO3 Na2SiO3

A less thermal method involves the reaction of calcium phosphate with sulfuric acid, which produces phosphoric acid. This is reduced with carbon and the phosphorus vapors are condensed underwater. [2]

Another method would require the thermal decomposition of copper phosphide:

4 Cu3P2 → 4 Cu3P + P4

The copper phosphide can be obtained by reducing copper(II) phosphate with a metal, (aluminium e.g.).

The the phosphorus obtained from all these methods is the gaseous diphosphorus form which, upon condensation, gives the white form, so the condensation of the raw phosphorus must be done underwater. Very little red P if any is produced during these routes.

Red phosphorus

To obtain red P, white phosphorus is placed in a thick stainless steel retort, with potassium iodide being added as a catalyst. The retort is heated to 250 °C for several hours, which results in impure red P, with plenty of unreacted white P. Upon opening, contact with air may cause the white P to catch fire, so it's best to open the container underwater.[3]

To safely remove the white P from the mixture, an organic solvent, like toluene or carbon disulfide is added to dissolve it. Decant the liquid and use a separatory funnel to separate the aqueous layer from the hazardous organic layer. Remove any large impurities by hand or with tweezers and finely grind the red P into a powder to see if there are any impurities left in the hardened blocks.

Projects

Handling

Safety

The white phosphorus allotrope presents a significant hazard because it's pyrophoric and produces phosphorus pentoxide and phosphoric acid fumes as residue, that are potent irritants. Chronic white phosphorus poisoning leads to necrosis of the jaw called "phossy jaw". Ingestion of white phosphorus may cause a medical condition known as "Smoking Stool Syndrome". White phosphorus also has some neurotoxic properties.

Make sure you never add white phosphorus in a sodium or potassium hydroxide solution, as it will release the toxic phosphine gas.[4]

Certain combinations of phosphorus with halides are extremely toxic.

Many organophosphate compounds are known nerve toxins as are its precursors.

Storage

White phosphorus should be stored in an inert atmosphere, underwater is best, and in dark, to prevent it from turning into red P. The other types of phosphorus do not require special storage, and can be safely stored in ordinary plastic or glass bottles.

Disposal

White phosphorus should be converted to phosphate ions, which are far less hazardous and can be safely disposed of, via different means, depending on the allotrope.

White phosphorus can be neutralized using a 1 M aqueous solution of copper(II) sulfate, using a 100% excess. Bleach can be used to neutralize any leftover phosphides, to prevent the formation of phosphine gas.

2 P + 5 Cu2+ + 8 H2O → 2 H3PO4 + 5 Cu + 10 H+

Red phosphorus can be neutralized using an aqueous solution of potassium chlorate:[5]

6 P + KClO3 + 9 H2O → 6 H3PO4 + 5 KCl

Gallery

References

  1. http://williestop.tripod.com/generalchemdata/redphosphorus.html
  2. Lange's Handbook of Chemistry
  3. https://www.youtube.com/watch?v=Cqn2szaTOUQ
  4. Rose, H.; Annalen der Physik (Weinheim, Germany); vol. 6; (1826); p. 199 - 214
  5. Prudent Practices for Disposal of Chemicals from Laboratories

Relevant Sciencemadness threads