Oxygen Element Facts

15.9994
Oxygen

Oxygen cylinders.

General:

Name: Oxygen	Symbol: O
Type: Non-Metal, Chalcogen	Atomic weight: 15.9994
Density @ 293 K: 0.001429 g/cm³	Atomic volume: 14.0 cm³/mol
Discovery of Oxygen Oxygen was discovered in 1774 by Joseph Priestley in England and two years earlier, but unpublished, by Carl W. Scheele in Sweden. Scheele heated several compounds including potassium nitrate, manganese oxide, and mercury oxide and found they released a gas which enhanced combustion. Priestley heated mercury oxide and found it yielded a gas that made a candle burn five times faster than normal. He wrote: "But what surprised me more than I can well express was that a candle burned in this air with a remarkably vigourous flame. I was utterly at a loss how to account for it." ⁽¹⁾ In addition to noticing the effect of oxygen on combustion, Priestley noted the new gas's biological role. In March 1775 he placed a mouse in a jar of oxygen, expecting it would survive for 15 minutes maximum before it suffocated. The mouse survived for 30 minutes in the jar and was revived none the worse for wear. ⁽²⁾ Antoine Lavoisier repeated Priestley's experiments, discovering that air contains 20 percent oxygen and that when any substance burns, it actually combines chemically with oxygen. It was Lavoisier who first gave the element its name oxygen. ^(2a) The word oxygen is derived from the Greek words 'oxys' meaning acid and 'genes' meaning forming.

States

State (s, l, g): gas
Melting point: 54.8 K (-218.3 ^oC)	Boiling point: 90.2 K (-182.9 ^oC)

Energies

Specific heat capacity: 0.918 J g^-1 K^-1	Heat of atomization: 249 kJ mol^-1
Heat of fusion: 0.444 kJ mol^-1 of O₂	Heat of vaporization: 6.82 kJ mol^-1 of O₂
1^st ionization energy: 1313.9 kJ mol^-1	2^nd ionization energy: 3388.2 kJ mol^-1
3^rd ionization energy: 5300.3 kJ mol^-1	Electron affinity: 140.97875 kJ mol^-1

Oxidation & Electrons

Shells: 2, 6	Electron configuration: [He] 2s² 2p⁴
Minimum oxidation number: -2	Maximum oxidation number: 25
Min. common oxidation no.: -2	Max. common oxidation no.: 0
Electronegativity (Pauling Scale): 3.44	Polarizability volume: 0.793 Å³

Appearance & Characteristics

Structure:	Color: Colorless
Harmful effects: O₂ is non-toxic under normal conditions. However, exposure to oxygen at higher than normal pressures, e.g. scuba divers, can lead to convulsions. Ozone (O₃) is toxic and if inhaled can damage the lungs.	Hardness: mohs
Watch steel melt when charcoal (carbon) burns in liquid oxygen. (Liquid oxygen is much more concentrated than the gas. Higher concentrations lead to faster reaction rates.) Liquid oxygen is pale blue and paramagnetic. Watch it stick to a magnet. (3 min 15 secs and onwards.)	Characteristics: Oxygen in its common form (O₂) is a colorless, odorless and tasteless diatomic gas. Oxygen is extremely reactive and forms oxides with nearly all other elements except noble gases. Earth's atmosphere at first contained no free oxygen. It only contains free oxygen now because green plants - not initially present on Earth - produce it during photosynthesis. If green plants were to disappear, all the oxygen in Earth's atmosphere would react over a period of time and the atmosphere would once again contain no free oxygen. If we discover any other planets with atmospheres rich in oxygen, we will be able to infer that life is almost certainly present on these planets. Liquid and solid oxygen are pale blue and are strongly paramagnetic. Ozone (O₃), another form (allotrope) of oxygen, occurs naturally in the Earth's upper atmosphere. The reaction with oxygen is one of the critera we use to distinguish between metals (these form basic oxides) and non-metals (these form acidic oxides). Uses: The major commercial use of oxygen is in steel production. Carbon impurities are removed from steel by reaction with oxygen to form carbon dioxide gas. Oxygen is also used in oxyacetylene welding, as an oxidant for rocket fuel, and in methanol and ethylene oxide production. Plants and animals rely on oxygen for respiration. Oxygen is frequently used to help breathing in patients with respiratory ailments. Naturally occurring ozone in the upper atmosphere shields the earth from ultraviolet radiation.

Reactions

Reaction with air: none	Reaction with 6 M HCl: none
Reaction with 15 M HNO₃: none	Reaction with 6 M NaOH: none

Compounds

Oxide(s): O₂, O₃	Chloride(s): Cl₂O, ClO₂
Hydride(s): H₂O

Radius

Atomic radius: 60 pm	Ionic radius (1+ ion): pm
Ionic radius (2+ ion): pm	Ionic radius (3+ ion): pm
Ionic radius (2- ion): 126 pm	Ionic radius (1- ion): pm

Conductivity

Thermal conductivity: 0.02583 W m^-1 K^-1

Electrical conductivity: S cm^-1

Abundance & Isotopes

Laboratory electrolysis of water. Electrical energy is used to split water. Watch out for the different ways the two gases are collected.

Abundance earth's crust: 46 % by weight, 60 % by moles

Abundance solar system: 9,000 ppm by weight, 700 ppm by moles

Cost, pure: $0.3 per 100g

Cost, bulk: $0.02 per 100g

Source: Oxygen is the most abundant element in the Earth's crust, accounting for almost half of it by mass. More than half of the atoms in the Earth's crust are oxygen atoms. About 86 percent of the mass of Earth's oceans is oxygen - mainly in the form of water. Oxygen is the third most common element in the Universe, behind hydrogen and helium. It is obtained commercially from liquefied air separation plants. It can be prepared in the laboratory by electrolysis of water.

Isotopes: 13 whose half-lives are known, with mass numbers 12 to 24. Of these, three are stable: ¹⁶O, ¹⁷O and ¹⁸O.

References

1. Francis Preston Venable: A Short History of Chemistry., (2009) p66. Bibliobazaar.
2. Leslie Alan Horvitz, Eureka!: Scientific Breakthroughs that Changed the World., (2002) p19. Wiley.
2a. Leslie Alan Horvitz, Eureka!: Scientific Breakthroughs that Changed the World., (2002) p20. Wiley.

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