Oxygen, atomic

Formula: O
Molecular weight: 15.9994
IUPAC Standard InChI: InChI=1S/O
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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Other data available:
- Gas phase ion energetics data
- Ion clustering data
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Gas phase thermochemistry data

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Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	59.555 ± 0.024	kcal/mol	Review	Cox, Wagman, et al., 1984	CODATA Review value
Quantity	Value	Units	Method	Reference	Comment
S°_{gas,1 bar}	38.4940 ± 0.0007	cal/mol*K	Review	Cox, Wagman, et al., 1984	CODATA Review value

Reaction thermochemistry data

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Data compiled by: John E. Bartmess

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.

Individual Reactions

( • 4294967295 Oxygen, atomic ) + =

By formula: (HO^- • 4294967295O) + O = HO^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	127.44	kcal/mol	N/A	Smith, Kim, et al., 1997	gas phase; Given: 14741.02(3) cm-1. dHacid(0K) = 389.11±0.014
Δ_rH°	127.60 ± 0.20	kcal/mol	Ther	Schulz, Mead, et al., 1982	gas phase; Given: 1.82767±0.00021 eV

(CAS Reg. No. 661-20-1 • 4294967295 Oxygen, atomic ) + = CAS Reg. No. 661-20-1

By formula: (CAS Reg. No. 661-20-1 • 4294967295O) + O = CAS Reg. No. 661-20-1

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	126.91	kcal/mol	N/A	Bradforth, Kim, et al., 1993	gas phase; D-EA cycle requires a DH ca 4 kcal/mol weaker
Δ_rH°	123.35	kcal/mol	Ther	Wight and Beauchamp, 1980	gas phase

( • 4294967295 Oxygen, atomic ) + =

By formula: (O₂^- • 4294967295O) + O = O₂^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	95.78	kcal/mol	N/A	Ervin, Anusiewicz, et al., 2003	gas phase
Δ_rH°	95.8 ± 1.0	kcal/mol	Ther	Travers, Cowles, et al., 1989	gas phase

(CAS Reg. No. 13981-20-9 • 4294967295 Oxygen, atomic ) + = CAS Reg. No. 13981-20-9

By formula: (CAS Reg. No. 13981-20-9 • 4294967295O) + O = CAS Reg. No. 13981-20-9

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	125.2 ± 7.1	kcal/mol	CIDT	Bell, Zemski, et al., 2001	gas phase

(CAS Reg. No. 14380-61-1 • 4294967295 Oxygen, atomic ) + = CAS Reg. No. 14380-61-1

By formula: (CAS Reg. No. 14380-61-1 • 4294967295O) + O = CAS Reg. No. 14380-61-1

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	33.47	kcal/mol	N/A	Distelrath and Boesl, 2000	gas phase

(CAS Reg. No. 12763-66-5 • 4294967295 Oxygen, atomic ) + = CAS Reg. No. 12763-66-5

By formula: (CAS Reg. No. 12763-66-5 • 4294967295O) + O = CAS Reg. No. 12763-66-5

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	26.44	kcal/mol	N/A	Gilles, Polak, et al., 1992	gas phase

(CAS Reg. No. 14380-62-2 • 4294967295 Oxygen, atomic ) + = CAS Reg. No. 14380-62-2

By formula: (CAS Reg. No. 14380-62-2 • 4294967295O) + O = CAS Reg. No. 14380-62-2

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	32.54	kcal/mol	N/A	Gilles, Polak, et al., 1992	gas phase

(CAS Reg. No. 15065-65-3 • 4294967295 Oxygen, atomic ) + = CAS Reg. No. 15065-65-3

By formula: (CAS Reg. No. 15065-65-3 • 4294967295O) + O = CAS Reg. No. 15065-65-3

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	40.19	kcal/mol	N/A	Gilles, Polak, et al., 1991	gas phase

References

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Notes

Cox, Wagman, et al., 1984
Cox, J.D.; Wagman, D.D.; Medvedev, V.A., CODATA Key Values for Thermodynamics, Hemisphere Publishing Corp., New York, 1984, 1. [all data]

Smith, Kim, et al., 1997
Smith, J.R.; Kim, J.B.; Lineberger, W.C., High-resolution Threshold Photodetachment Spectroscopy of OH-, Phys. Rev. A, 1997, 55, 3, 2036, https://doi.org/10.1103/PhysRevA.55.2036 . [all data]

Schulz, Mead, et al., 1982
Schulz, P.A.; Mead, R.D.; Jones, P.L.; Lineberger, W.C., OH- and OD- threshold photodetachment, J. Chem. Phys., 1982, 77, 1153. [all data]

Bradforth, Kim, et al., 1993
Bradforth, S.E.; Kim, E.H.; Arnold, D.W.; Neumark, D.M., Photoelectron Spectroscopy of CN-, NCO-, and NCS-, J. Chem. Phys., 1993, 98, 2, 800, https://doi.org/10.1063/1.464244 . [all data]

Wight and Beauchamp, 1980
Wight, C.A.; Beauchamp, J.L., Acidity, basicity, and ion/molecule reactions of isocyanic acid in the gas phase by ICR spectroscopy, J. Phys. Chem., 1980, 84, 2503. [all data]

Ervin, Anusiewicz, et al., 2003
Ervin, K.M.; Anusiewicz, W.; Skurski, P.; Simons, J.; Lineberger, W.C., The only stable state of O-2(-) is the X (2)Pi(g) ground state and it (still!) has an adiabatic electron detachment energy of, J. Phys. Chem. A, 2003, 107, 41, 8521-8529, https://doi.org/10.1021/jp0357323 . [all data]

Travers, Cowles, et al., 1989
Travers, M.J.; Cowles, D.C.; Ellison, G.B., Reinvestigation of the Electron Affinities of O2 and NO, Chem. Phys. Lett., 1989, 164, 5, 449, https://doi.org/10.1016/0009-2614(89)85237-6 . [all data]

Bell, Zemski, et al., 2001
Bell, R.C.; Zemski, K.A.; Justes, D.R.; Castleman, A.W., Formation, structure and bond dissociation thresholds of gas- phase vanadium oxide cluster ions, J. Chem. Phys., 2001, 114, 2, 798-811, https://doi.org/10.1063/1.1329643 . [all data]

Distelrath and Boesl, 2000
Distelrath, V.; Boesl, U., Mass selective gas phase study of ClO, OClO, ClOO and ClAr by anion-ZEKE-photoelectron spectroscopy, Faraday Disc. Chem. Soc., 2000, 115, 161-174, https://doi.org/10.1039/a909618c . [all data]

Gilles, Polak, et al., 1992
Gilles, M.K.; Polak, M.L.; Lineberger, W.C., Photoelectron Spectroscopy of the Halogen Oxide Anions FO-, ClO-, BrO-, IO-, OClO-, and OIO-, J. Chem. Phys., 1992, 96, 11, 8012, https://doi.org/10.1063/1.462352 . [all data]

Gilles, Polak, et al., 1991
Gilles, M.K.; Polak, M.L.; Lineberger, W.C., Photoelectron Spectroscopy of IO-, J. Chem. Phys., 1991, 95, 6, 4723, https://doi.org/10.1063/1.461746 . [all data]

Notes

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Symbols used in this document:

S°_{gas,1 bar} Entropy of gas at standard conditions (1 bar)

Δ_fH°_gas Enthalpy of formation of gas at standard conditions

Δ_rH° Enthalpy of reaction at standard conditions
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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S°_{gas,1 bar}	Entropy of gas at standard conditions (1 bar)
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions