Difference between revisions of "Oxygen"

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'''Oxygen''' is the 8th element on the periodic table and is the second strongest [[oxidizer]], second to fluorine. It has the atomic weight of ~16 (15.9949), but as a gas it is diatomic with a molar mass of ~32.
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{{Infobox element
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<!-- General properties -->
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|name=Oxygen
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|symbol=O
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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=Dioxygen, [[ozone]], tetraoxygen
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|appearance=Colorless (gas)<br>Blueish liquid (liquid)
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<!-- Periodic table -->
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|above=-
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|below=[[Sulfur|S]]
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|left=[[Nitrogen]]
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|right=[[Fluorine]]
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|number=8
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|atomic mass=15.999
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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=16
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|group ref=
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|group comment=(chalcogens)
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|period=2
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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=[He] 2s<sup>2</sup> 2p<sup>4</sup>
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|electron configuration ref=
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|electron configuration comment=
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|electrons per shell=2, 6
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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=Colorless
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|phase=Gas
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|phase ref=
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|phase comment=
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|melting point K=54.36
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|melting point C=−218.79
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|melting point F=−361.82
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|melting point ref=
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|melting point comment=
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|boiling point K=90.188
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|boiling point C=−182.962
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|boiling point F=−297.332
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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 comment=
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|density gplstp=1.429
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|density gpcm3nrt=
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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=1.141
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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=54.361
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|triple point kPa=0.1463
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|triple point K 2=
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|triple point 2 comment=
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|critical point K=154.581
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|critical point MPa=5.043
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|critical point ref=
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|critical point comment=
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|heat fusion=0.444
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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=6.82
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|heat vaporization ref=
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|heat vaporization comment=
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|heat capacity=29.378
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|heat capacity ref=
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|heat capacity comment=
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|vapor pressure 1=
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|vapor pressure 10=
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|vapor pressure 100=
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|vapor pressure 1 k=61
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|vapor pressure 10 k=73
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|vapor pressure 100 k=90
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<!-- Atomic properties -->
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|atomic properties comment=
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|oxidation states=2, 1, −1, '''−2'''
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|oxidation states ref=
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|oxidation states comment=
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|electronegativity=3.44
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|electronegativity ref=
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|electronegativity comment=
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|ionization energy 1=1313.9
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|ionization energy 1 ref=
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|ionization energy 1 comment=
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|ionization energy 2=3388.3
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|ionization energy 2 ref=
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|ionization energy 2 comment=
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|ionization energy 3=5300.5
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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 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=66±2
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|covalent radius ref=
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|covalent radius comment=
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|Van der Waals radius=152
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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=Cubic
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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=330 m/s (gas, at 27 °C)
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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 r.t.=
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|thermal expansion at 25=
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|thermal conductivity=26.58×10<sup>−3</sup>
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|Curie point K=
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|magnetic ordering=Paramagnetic
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|CAS number=7782-44-7
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<!-- History -->
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|predicted by=
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|discovered by=Carl Wilhelm Scheele (1771)
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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= Antoine Lavoisier (1777)
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<!-- Isotopes -->
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|engvar=
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}}
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'''Oxygen''' (symbol: '''O''') is the 8th element on the periodic table and is the second strongest [[oxidizer]], second to [[fluorine]]. It has the atomic weight of ~16 (15.9949), but as a gas it is diatomic with a molar mass of ~32.
  
 
==Properties==
 
==Properties==
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It is highly electronegative, with a 3.44 on the Pauling scale. It reacts directly with almost every element, a major exception being most of the noble metals and gases (except for [[xenon]]).
 
It is highly electronegative, with a 3.44 on the Pauling scale. It reacts directly with almost every element, a major exception being most of the noble metals and gases (except for [[xenon]]).
  
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It reacts with many metals to form oxides. These reactions can be slow and gradual (as is the rusting of [[iron]]) or extremely fast, as in the combustion of [[cesium]].
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It reacts with many metals to form oxides. These reactions can be slow and gradual (as is the rusting of [[iron]]) or extremely fast, as in the combustion of [[caesium|cesium]].
  
 
===Physical===
 
===Physical===
 
Although in gas form it is indistinguishable from other common gases, in liquid form it is pale blue (and highly reactive). Oxygen is paramagnetic.
 
Although in gas form it is indistinguishable from other common gases, in liquid form it is pale blue (and highly reactive). Oxygen is paramagnetic.
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Oxygen has several allotrope forms, with dioxygen and [[ozone]] (trioxygen) being the most important.
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Under normal conditions dioxygen exists in a triplet state denoted by the term symbol <sup>3</sup>Σ<sup>-</sup><sub>g</sub> or simplified chemically <sup>3</sup>O<sub>2</sub>. However, it is possible to create dioxygen in the singlet state usually denoted by <sup>1</sup>Δ<sub>g</sub> (or simplified <sup>1</sup>O<sub>2</sub>) photochemically or from, for example, the reaction of hypochlorite and hydrogen peroxide. At high concentrations of singlet oxygen, a red chemiluminescence is observed when the oxygen returns to the ground state:
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: NaOCl + H<sub>2</sub>O<sub>2</sub> → NaCl + H<sub>2</sub>O + <sup>1</sup>O<sub>2</sub>
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: <sup>1</sup>O<sub>2</sub> → <sup>3</sup>O<sub>2</sub> + hv
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To be precise, two transitions cause the red glow:<ref> P. Lechtken, ''Chemie in unserer Zeit'' '''1974''', 8, 11-16, [https://doi.org/10.1002/ciuz.19740080103 doi:10.1002/ciuz.19740080103]</ref>
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: 2 O<sub>2</sub> (<sup>1</sup>Δ<sub>g</sub>) → 2 O<sub>2</sub> (<sup>3</sup>Σ<sup>-</sup><sub>g</sub>) + hv (λ = 633.4 nm)
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: O<sub>2</sub> (<sup>3</sup>Σ<sup>+</sup><sub>g</sub>) → O<sub>2</sub> (<sup>3</sup>Σ<sup>-</sup><sub>g</sub>) + hv (λ = 703.2 nm)
  
 
==Availability==
 
==Availability==
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A way to make liquid oxygen involves liquifying normal air with liquid nitrogen and collecting the oxygen-rich layer on top.
 
A way to make liquid oxygen involves liquifying normal air with liquid nitrogen and collecting the oxygen-rich layer on top.
  
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==Safety==
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==Handling==
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===Safety===
 
Atmospheric oxygen is not a hazard to health, however at high concentration it becomes dangerous to the lungs and can cause blindness. At concentrations over 50%, it will greatly amplify any exothermic reaction. Liquid oxygen is a fire and explosive hazard when in contact with organic materials and a fire source. It can also cause frostbites if it touches the skin.
 
Atmospheric oxygen is not a hazard to health, however at high concentration it becomes dangerous to the lungs and can cause blindness. At concentrations over 50%, it will greatly amplify any exothermic reaction. Liquid oxygen is a fire and explosive hazard when in contact with organic materials and a fire source. It can also cause frostbites if it touches the skin.
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===Storage===
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Oxygen tanks and dewars should be kept in dark and cool places, away from any combustible materials. Periodically check the valves for any leaks.
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===Disposal===
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Oxygen can be safely released in open air, but never in closed places.
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==Gallery==
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<gallery widths="200" position="center" columns="4" orientation="none">
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Singlet_oxygen.jpg|Chemiluminescence of singlet oxygen
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</gallery>
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==See also==
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*[[Ozone]]
  
 
==References==
 
==References==
 
<references/>
 
<references/>
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==Relevant Sciencemadness threads==
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===Relevant Sciencemadness threads===
 
*[http://www.sciencemadness.org/talk/viewthread.php?tid=23211 LOX (Liquid Oxygen)]
 
*[http://www.sciencemadness.org/talk/viewthread.php?tid=23211 LOX (Liquid Oxygen)]
  

Latest revision as of 19:23, 13 August 2022

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Oxygen,  8O
General properties
Name, symbol Oxygen, O
Allotropes Dioxygen, ozone, tetraoxygen
Appearance Colorless (gas)
Blueish liquid (liquid)
Oxygen in the periodic table
-
↑
O
↓
S
Nitrogen ← Oxygen → Fluorine
Atomic number 8
Standard atomic weight (Ar) 15.999
Group, block (chalcogens); p-block
Period period 2
Electron configuration [He] 2s2 2p4
per shell
 2, 6
Physical properties
Colorless
Phase Gas
Melting point 54.36 K ​(−218.79 °C, ​−361.82 °F)
Boiling point 90.188 K ​(−182.962 °C, ​−297.332 °F)
Density at  (0 °C and 101.325 kPa) 1.429 g/L
when liquid, at  1.141 g/cm3
Triple point 54.361 K, ​0.1463 kPa
Critical point 154.581 K, 5.043 MPa
Heat of fusion 0.444 kJ/mol
Heat of 6.82 kJ/mol
Molar heat capacity 29.378 J/(mol·K)
 pressure
Atomic properties
Oxidation states 2, 1, −1, −2
Electronegativity Pauling scale: 3.44
energies 1st: 1313.9 kJ/mol
2nd: 3388.3 kJ/mol
3rd: 5300.5 kJ/mol
Covalent radius 66±2 pm
Van der Waals radius 152 pm
Miscellanea
Crystal structure ​Cubic
Speed of sound 330 m/s (gas, at 27 °C)
Thermal conductivity 26.58×10−3 W/(m·K)
Magnetic ordering Paramagnetic
CAS Registry Number 7782-44-7
History
Discovery Carl Wilhelm Scheele (1771)
Named by Antoine Lavoisier (1777)
· references

Oxygen (symbol: O) is the 8th element on the periodic table and is the second strongest oxidizer, second to fluorine. It has the atomic weight of ~16 (15.9949), but as a gas it is diatomic with a molar mass of ~32.

Properties

Chemical

Oxygen has 6 valence electrons and typically exists with two lone pairs of electrons.

It is highly electronegative, with a 3.44 on the Pauling scale. It reacts directly with almost every element, a major exception being most of the noble metals and gases (except for xenon).

It reacts with many metals to form oxides. These reactions can be slow and gradual (as is the rusting of iron) or extremely fast, as in the combustion of cesium.

Physical

Although in gas form it is indistinguishable from other common gases, in liquid form it is pale blue (and highly reactive). Oxygen is paramagnetic.

Oxygen has several allotrope forms, with dioxygen and ozone (trioxygen) being the most important.

Under normal conditions dioxygen exists in a triplet state denoted by the term symbol 3Σ-g or simplified chemically 3O2. However, it is possible to create dioxygen in the singlet state usually denoted by 1Δg (or simplified 1O2) photochemically or from, for example, the reaction of hypochlorite and hydrogen peroxide. At high concentrations of singlet oxygen, a red chemiluminescence is observed when the oxygen returns to the ground state:

NaOCl + H2O2 → NaCl + H2O + 1O2
1O2 → 3O2 + hv

To be precise, two transitions cause the red glow:[1]

2 O2 (1Δg) → 2 O2 (3Σ-g) + hv (λ = 633.4 nm)
O2 (3Σ+g) → O2 (3Σ-g) + hv (λ = 703.2 nm)

Availability

Gaseous oxygen makes up 21% of the atmosphere. For higher concentrations, compressed oxygen can be procured from the companies that sell welding products as well as scuba diving stores. Cryogenic liquid oxygen is harder to get because unlike liquid nitrogen it is a fire and explosive hazard, when it (accidentally) enters in contact with organic materials.

Preparation

Oxygen is extracted from air by fractional distillation on an industrial scale.

In the lab, it can be isolated by:

  • electrolysis of water with containing ions
  • heating potassium chlorate with manganese dioxide,
  • decomposing hydrogen peroxide with manganese dioxide
  • Decomposition of hypochlorite solution (laundry bleach) using a small amount of cobalt chloride as a catalyst
  • heating potassium permanganate.

A way to make liquid oxygen involves liquifying normal air with liquid nitrogen and collecting the oxygen-rich layer on top.

Handling

Safety

Atmospheric oxygen is not a hazard to health, however at high concentration it becomes dangerous to the lungs and can cause blindness. At concentrations over 50%, it will greatly amplify any exothermic reaction. Liquid oxygen is a fire and explosive hazard when in contact with organic materials and a fire source. It can also cause frostbites if it touches the skin.

Storage

Oxygen tanks and dewars should be kept in dark and cool places, away from any combustible materials. Periodically check the valves for any leaks.

Disposal

Oxygen can be safely released in open air, but never in closed places.

Gallery

  • Chemiluminescence of singlet oxygen

See also

References

  1. ↑ P. Lechtken, Chemie in unserer Zeit 1974, 8, 11-16, doi:10.1002/ciuz.19740080103

Relevant Sciencemadness threads

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