Difference between revisions of "Oxygen"

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The discovery of oxygen is often credited to English chemist [[Joseph Priestley]], although the full story is somewhat more involved. That there is a component of air which is necessary for combustion and respiration was recognized by [[Leonardo da Vinci]] in the fifteenth century, and confirmed by English chemist [[John Mayow]] in the mid-seventeenth century.<ref>{{citation | contribution = De sal-nitro et spiritu nitro-aereo | title = Tractatus quinque medico-physici | last = Mayow | first = John | authorlink = John Mayow | year = 1674 | location = Oxford}}, summarized in {{citation | journal = Phil. Trans. R. Soc. London | year = 1674 | volume = 9 | pages = 101–113 | url = http://gallica.bnf.fr/ark:/12148/bpt6k558143.image.f110.langEN}}.</ref> However, the interpretation of these results was hampered by the rise of [[phlogiston]] theory, which stated that substances gave off phlogiston during combustion: air that was no longer capable of supporting combustion was said to be saturated with phlogiston. The unequivocal identification of oxygen as a chemical substance would have to wait for its preparation by chemical means.
 
The discovery of oxygen is often credited to English chemist [[Joseph Priestley]], although the full story is somewhat more involved. That there is a component of air which is necessary for combustion and respiration was recognized by [[Leonardo da Vinci]] in the fifteenth century, and confirmed by English chemist [[John Mayow]] in the mid-seventeenth century.<ref>{{citation | contribution = De sal-nitro et spiritu nitro-aereo | title = Tractatus quinque medico-physici | last = Mayow | first = John | authorlink = John Mayow | year = 1674 | location = Oxford}}, summarized in {{citation | journal = Phil. Trans. R. Soc. London | year = 1674 | volume = 9 | pages = 101–113 | url = http://gallica.bnf.fr/ark:/12148/bpt6k558143.image.f110.langEN}}.</ref> However, the interpretation of these results was hampered by the rise of [[phlogiston]] theory, which stated that substances gave off phlogiston during combustion: air that was no longer capable of supporting combustion was said to be saturated with phlogiston. The unequivocal identification of oxygen as a chemical substance would have to wait for its preparation by chemical means.
  
−
The preparation was first carried out by Swedish chemist [[Carl Scheele]] on several occasions during the period 1771–73. Scheele heated various compounds such as [[Potassium nitrate|KNO<sub>3</sub>]], [[Magnesium nitrate|Mg(NO<sub>3</sub>)<sub>2</sub>]] and [[Mercury(II) oxide|HgO]] and found that they gave off a gas that he named "vitriol air", which supported combustion better than normal air.<ref name="G&E">{{Greenwood&Earnshaw1st|pages=698–756}}.</ref> Scheele's results, however, were not published until 1777. In the meantime, Priestley had isolated the gas given off by heating HgO and named it "dephlogistonated air", and published his results in 1775 after proving that the gas was different from [[nitrous oxide]].
+
The preparation was first carried out by Swedish chemist [[Carl Scheele]] on several occasions during the period 1771–73. Scheele heated various compounds such as [[Potassium nitrate|KNO<sub>3</sub>]], [[Magnesium nitrate|Mg(NO<sub>3</sub>)<sub>2</sub>]] and [[Mercury(II) oxide|HgO]] and found that they gave off a gas that he named "vitriol air", which supported combustion better than normal air.<ref name="G&E">{{Greenwood&Earnshaw1st|pages=698–756}}.</ref> Scheele's results, however, were not published until 1777.<ref>{{citation | first = Carl Wilhelm | last = Scheele | author link = Carl Scheele | title = Chemische Abhandlung von der Luft und dem Feuer | location = Uppsala and Leipzig | year = 1777}}; [http://web.lemoyne.edu/~giunta/scheele77.html Translated extracts].</ref> In the meantime, Priestley had isolated the gas given off by heating HgO and named it "dephlogistonated air", and published his results in 1775 after proving that the gas was different from [[nitrous oxide]].
  
 
Priestley's work certainly had the greater impact, as he was able to discuss it with French chemist [[Antoine Lavoisier]] in October 1774 during a visit to Paris with his mentor and employer the Earl of Shelbourne.
 
Priestley's work certainly had the greater impact, as he was able to discuss it with French chemist [[Antoine Lavoisier]] in October 1774 during a visit to Paris with his mentor and employer the Earl of Shelbourne.

Revision as of 17:02, 3 April 2010

nitrogen ← oxygen → fluorine
–
↑
O
↓
S
Atomic properties
Atomic number 8
Standard atomic weight 15.9994(3)
Electron configuration [He] 2s2 2p4
Physical properties (O2)[1][2]
Melting point 54.8(2) K (−218.8 °C)
Boiling point 90.2(2) K (−183.0 °C)
Triple point 54.35 K, 1.52 mbar
Critical point 154.58 K, 50.43 bar
Density 1.354 kg m−3 (1 atm, 15 °C)
4.475 kg m−3 (1 atm, 90.2 K)
1.141 g cm−3 (l, 90.2 K)
Chemical properties[3]
Electronegativity 3.44 (Pauling)
Solubility in water 48.9 cm3 dm−3 (1 atm, 0 °C)
Ionization energies[4][5]
1st 13.618 06 eV,
1313.943 kJ mol−1
2nd 35.1211 eV,
3388.67 kJ mol−1
3rd 54.9355 eV,
5300.47 kJ mol−1
4th 77.4135 eV,
7469.27 kJ mol−1
5th 113.8989 eV,
10 989.57 kJ mol−1
6th 138.1196 eV,
13 326.52 kJ mol−1
7th 739.3268 eV,
71 334.20 kJ mol−1
8th 871.4097 eV,
84 078.26 kJ mol−1
Total 2043.8432 eV,
197 200.9 kJ mol−1
Electron affinity[4]
140.9759(42) kJ mol−1
Atomic radii [6][7][8]
Covalent radius 66(2) pm
Ionic radius 140 pm (O2−, Oh)
Van der Waals radius 152 pm
Thermodynamic properties (O2)[1][9]
Standard entropy 205.152(5) J K−1 mol−1
Enthalpy change of atomization 249.18(10) kJ mol−1
Entropy change of atomization −44.093(6) J K−1 mol−1
Enthalpy change of fusion 0.444 kJ mol−1
Enthalpy change of vaporization 6.82 kJ mol−1
Molar heat capacity (Cp) 29.378 J K−1 mol−1
Miscellaneous
CAS number 7782-44-7 (O2)
17778-80-2 (atomic)
EC number 231-956-9
Where appropriate, and unless otherwise stated, data are given for 100 kPa (1 bar) and 298.15 K (25 °C).
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Oxygen (ˈɒksɨdʒɨn) is a colourless gas which makes up about one fifth of the Earth's atmosphere. Its name comes from the Greek ὀξύς (oxys; acid, literally "sharp", from the taste of acids) and -γενής (-genēs; producer, literally "begetter").

History

The discovery of oxygen is often credited to English chemist Joseph Priestley, although the full story is somewhat more involved. That there is a component of air which is necessary for combustion and respiration was recognized by Leonardo da Vinci in the fifteenth century, and confirmed by English chemist John Mayow in the mid-seventeenth century.[10] However, the interpretation of these results was hampered by the rise of phlogiston theory, which stated that substances gave off phlogiston during combustion: air that was no longer capable of supporting combustion was said to be saturated with phlogiston. The unequivocal identification of oxygen as a chemical substance would have to wait for its preparation by chemical means.

The preparation was first carried out by Swedish chemist Carl Scheele on several occasions during the period 1771–73. Scheele heated various compounds such as KNO3, Mg(NO3)2 and HgO and found that they gave off a gas that he named "vitriol air", which supported combustion better than normal air.[11] Scheele's results, however, were not published until 1777.[12] In the meantime, Priestley had isolated the gas given off by heating HgO and named it "dephlogistonated air", and published his results in 1775 after proving that the gas was different from nitrous oxide.

Priestley's work certainly had the greater impact, as he was able to discuss it with French chemist Antoine Lavoisier in October 1774 during a visit to Paris with his mentor and employer the Earl of Shelbourne.

Occurance and production

Oxygen is almost ubiquitous at the surface of the Earth. The approximate mass fractions of oxygen are: crustal rocks 46%; the human body 61%; sea water 86%. The amount fraction of oxygen in the Earth's atmosphere (at sea level) is 21.0%, amounting to some 1015 tonnes. Apart from the atmosphere, the vast majority of this oxygen is chemically combined in a wide variety of inorganic and organic compounds: in the atmosphere, oxygen exists almost entirely as dioxygen (O2) molecules, its normal elemental state, with a small (but very important) amount of ozone (O3).

While it is difficult to obtain precise statistics, oxygen is believed to be the third most important bulk industrial chemical, after sulfuric acid and lime but ahead of ammonia and nitrogen, with production of at least 100 million tonnes per year.

Use

Allotropes

Main articles: Dioxygen and Ozone

Chemical properties

Water and hydrogen peroxide

Main articles: Water and Hydrogen peroxide

Oxides

Main article: Oxide

Dioxygen as a ligand

Main article: Dioxygen complexes

Organic compunds of oxygen

Biological role

Physical properties

Safety

Notes and references

Notes

References

  1. ↑ 1.0 1.1 Oxygen. In NIST Chemistry WebBook; National Institute for Standards and Technology, <http://webbook.nist.gov/cgi/inchi/InChI%3D1S/O2/c1-2>. (accessed 15 March 2010).
  2. ↑ Oxygen. In Gas Encyclopedia; Air Liquide, <http://encyclopedia.airliquide.com/encyclopedia.asp?GasID=48>. (accessed 3 April 2010).
  3. ↑ Allred, A. L. Electronegativity values from thermochemical data. J. Inorg. Nucl. Chem. 1961, 17 (3–4), 215–21. DOI: 10.1016/0022-1902(61)80142-5.
  4. ↑ 4.0 4.1 Oxygen, atomic. In NIST Chemistry WebBook; National Institute for Standards and Technology, <http://webbook.nist.gov/cgi/inchi/InChI%3D1S/O>. (accessed 15 March 2010).
  5. ↑ Mohr, Peter J.; Taylor, Barry N. CODATA recommended values of the fundamental physical constants: 2002. Rev. Mod. Phys. 2005, 77 (1), 1–107. DOI: 10.1103/RevModPhys.77.1.
  6. ↑ Cordero, Beatriz; Gómez, Verónica; Platero-Prats, Ana E.; Revés, Marc; Echeverría, Jorge; Cremades, Eduard; Barragán, Flavia; Alvarez, Santiago Covalent radii revisited. Dalton Trans. 2008 (5), 2832–38. DOI: 10.1039/b801115j.
  7. ↑ Shannon, R. D. Revised effective ionic radii and systematic studies of interatomic distances in halids and chalcogenides. Acta Crystallogr. A 1976, 32 (5), 751–67. DOI: 10.1107/S0567739476001551.
  8. ↑ Bondi, A. van der Waals Volumes and Radii. J. Phys. Chem. 1964, 68 (3), 441–51. DOI: 10.1021/j100785a001.
  9. ↑ Cox, J. D.; Wagman, D. D.; Medvedev, V. A. CODATA Key Values for Thermodynamics; Hemisphere: New York, 1989. ISBN 0891167587, <http://www.codata.org/resources/databases/key1.html>.
  10. ↑ Mayow, John De sal-nitro et spiritu nitro-aereo. In Tractatus quinque medico-physici; Oxford, 1674, summarized in Phil. Trans. R. Soc. London 1674, 9, 101–113, <http://gallica.bnf.fr/ark:/12148/bpt6k558143.image.f110.langEN>.
  11. ↑ Greenwood, Norman N.; Earnshaw, A. Chemistry of the Elements; Pergamon: Oxford, 1984; pp 698–756. ISBN 0-08-022057-6.
  12. ↑ Scheele, Carl Wilhelm Chemische Abhandlung von der Luft und dem Feuer; Uppsala and Leipzig, 1777; Translated extracts.

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