Given the relatively small uncertainties in the best 'absolute' measurements (0.25 ‰) and in typical relative measurements (0.1 ‰ or less), it is evident that the uncertainty of the standard atomic weight of oxygen is dominated by real natural variations. World Wide Web version of atomic weight data originally prepared by G. Moss, from a file provided by D. Previous values may be consulted from the 1993 table, the 1995 table, the 1997 table, the 1999 table, the 2001 table, the 2005 table, the 2007 table, the 2009 table, the 2011 table, the 2013 table or the 2015 table. 'Everybody knows that the binding energy of atomic oxygen is very important,' says Jiao He, an experimental astrophysicist at Syracuse University in New York. 'But there was no experimental.

The key difference between atomic oxygen and molecular oxygen is that the atomic oxygen is highly reactive and does not exist in the atmosphere as it is whereas the molecular oxygen is less reactive and exists in the atmosphere as it is. Moreover, atomic oxygen is a free radical having the symbol O(3P) while the molecular oxygen is a diatomic oxygen having the symbol O₂.

Oxygen is a chemical element having the atomic number 8. But when we refer to oxygen in common use, we are talking about molecular oxygen that we breathe. It has two oxygen atoms bonded to each other via covalent bond. Atomic oxygen has one oxygen atom. Therefore, it cannot exist as an individual chemical species because of its high reactivity.

1. Overview and Key Difference
2. What is Atomic Oxygen
3. What is Molecular Oxygen
4. Side by Side Comparison – Atomic Oxygen vs Molecular Oxygen in Tabular Form
5. Summary

Atomic No Of Oxygen In Blood

What is Atomic Oxygen?

Atomic No Of Oxygen Gas

Atomic oxygen is a very reactive chemical species having the symbol O(3P). It is a free radical. This means atomic oxygen has an unpaired electron that makes this atom highly reactive. Therefore, this atom does not exist naturally for even a short period; it tends to react with other chemical elements or compounds to become stable by pairing its unpaired electron.

However, in outer space, about 96% of oxygen exists as atomic oxygen because there UV radiation results in a low earth orbits atmosphere. This chemical species plays a major role in corrosion in space. Corrosion in space is the corrosion of materials occurring in outer space.

What is Molecular Oxygen?

Molecular oxygen is diatomic oxygen having the symbol O₂. It contains two oxygen atoms bonded to each other via covalent bonding. There is a double bond between these two atoms. Since the two oxygen atoms have eight electrons around them, the oxygen molecule is less reactive.

Figure 02: Formation of Molecular Oxygen

Therefore, this chemical species exist in the atmosphere itself. Our atmosphere has about 21% molecular oxygen. This amount of oxygen is essential for all the organisms for their respiration. It exists as a colorless gas and the boiling point is −183 °C.

What is the Difference Between Atomic Oxygen and Molecular Oxygen?

Atomic oxygen is a very reactive chemical species having the symbol O(3P). It does not exist naturally for even a short period, but in outer space, it is the predominant form of oxygen. Moreover, it is highly reactive. Molecular oxygen is diatomic oxygen which has the symbol O₂. It exists as itself in our atmosphere (about 21%). In addition, it is less reactive.

Summary – Atomic Oxygen vs Molecular Oxygen

Atomic and molecular oxygen are chemical species derived from the chemical element, oxygen which has the atomic number 8. The difference between atomic oxygen and molecular oxygen is that atomic oxygen is highly reactive and does not exist in the atmosphere as it is whereas molecular oxygen is less reactive and exists in the atmosphere as it is.

Reference:

1. “Allotropes of Oxygen.” Wikipedia, Wikimedia Foundation, 26 May 2018. Available here
2. Leenhouts, Doug. “The Differences of Oxygen & Oxygen Gas.” Sciencing, 24 Apr. 2017. Available here

Image Courtesy:

1.’Electron shell 008 Oxygen – no label’By Pumbaa (original work by Greg Robson) (CC BY-SA 2.0 uk) via Commons Wikimedia
2.’Figure 02 01 09’By CNX OpenStax,(CC BY 4.0) via Commons Wikimedia

Formula: O
Molecular weight: 15.9994
IUPAC Standard InChI:
InChI=1S/O
Download the identifier in a file.
IUPAC Standard InChIKey:QVGXLLKOCUKJST-UHFFFAOYSA-N
CAS Registry Number: 17778-80-2
Chemical structure:
This structure is also available as a 2d Mol file
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Gas phase ion energetics data

Go To:Top, References, Notes

Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias
L - Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess
LL - Sharon G. Lias and Joel F. Liebman
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	13.61806	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	485.2	kJ/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	459.6	kJ/mol	N/A	Hunter and Lias, 1998	HL

Electron affinity determinations

EA (eV)	Method	Reference	Comment
1.439157 ± 0.000004	LPD	Joiner, Mohr, et al., 2011	Given: 11607.75(28) cm-1. In 1.0 T field, 0.5 kcal/mol lower than 'best' EA; B
1.4610 ± 0.0010	LPES	Cavanagh, Gibson, et al., 2007	B
1.460982 ± 0.000044	LPD	Blondel, Chaibi, et al., 2005	(16)O: 1.4611135(12) eV: revised analysis of Blondel, Delsart, et al., 2001; B
1.461112 ± 0.000044	LPD	Neumark, Lykke, et al., 1985	Given: 1.461122(3) eV; revised to 1.4611107(17) eV, 95BLO, based on missing term+86CODATA; B
1.461112 ± 0.000044	N/A	Valli, Blondel, et al., 1999	16O: 11784.682(20) cm-1; 18O: 11784.612(29) cm-1 or 8.7μeV lower.; B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
13.61806	EVAL	Lide, 1992	LL
13.618	S	Kelly, 1987	LBLHLM
13.0 ± 0.5

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