helium

• Formula: He
• Molecular weight: 4.002602
• IUPAC Standard InChI: InChI=1S/He Copy

  
• IUPAC Standard InChIKey: SWQJXJOGLNCZEY-UHFFFAOYSA-N Copy
• CAS Registry Number: 7440-59-7
• Chemical structure:
  This structure is also available as a 2d Mol file
• Permanent link for this species. Use this link for bookmarking this species for future reference.
• Information on this page:
  • Gas phase thermochemistry data
  • Reaction thermochemistry data
  • Gas phase ion energetics data
  • References
  • Notes
• Other data available:
  • Phase change data
  • Henry's Law data
  • Ion clustering data
  • Fluid Properties
• Data at other public NIST sites:
  • NIST Atomic Spectra Database - Lines Holdings (on physics web site)
  • NIST Atomic Spectra Database - Levels Holdings (on physics web site)
  • NIST Atomic Spectra Database - Ground states and ionization energies (on physics web site)
  • Electron-Impact Ionization Cross Sections (on physics web site)
  • Gas Phase Kinetics Database
• Options:
  • Switch to SI units

Data at NIST subscription sites:

• NIST / TRC Web Thermo Tables, "lite" edition (thermophysical and thermochemical data)
• NIST / TRC Web Thermo Tables, professional edition (thermophysical and thermochemical data)

NIST subscription sites provide data under the NIST Standard Reference Data Program, but require an annual fee to access. The purpose of the fee is to recover costs associated with the development of data collections included in such sites. Your institution may already be a subscriber. Follow the links above to find out more about the data in these sites and their terms of usage.

Gas phase thermochemistry data

Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Gas Phase Heat Capacity (Shomate Equation)

C_p° = A + B*t + C*t² + D*t³ + E/t²
H° − H°_298.15= A*t + B*t²/2 + C*t³/3 + D*t⁴/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t²/2 + D*t³/3 − E/(2*t²) + G
    C_p = heat capacity (cal/mol*K)
    H° = standard enthalpy (kcal/mol)
    S° = standard entropy (cal/mol*K)
    t = temperature (K) / 1000.

View plot Requires a JavaScript / HTML 5 canvas capable browser.

View table.

Reaction thermochemistry data

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: Michael M. Meot-Ner (Mautner) and Sharon G. Lias

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

 +  = ( • )

By formula: Li⁺ + He = (Li⁺ • He)

Free energy of reaction

( • 2) +  = ( • 3)

By formula: (Ni⁺ • 2He) + He = (Ni⁺ • 3He)

( • 2) +  = ( • 3)

By formula: (Co⁺ • 2He) + He = (Co⁺ • 3He)

( • ) +  = ( • 2)

By formula: (Ni⁺ • He) + He = (Ni⁺ • 2He)

( • ) +  = ( • 2)

By formula: (Co⁺ • He) + He = (Co⁺ • 2He)

 +  = ( • )

By formula: Cr⁺ + He = (Cr⁺ • He)

 +  = ( • )

By formula: Ni⁺ + He = (Ni⁺ • He)

 +  = ( • )

By formula: Co⁺ + He = (Co⁺ • He)

(He⁺ • ) +  = (He⁺ • 2)

By formula: (He⁺ • He) + He = (He⁺ • 2He)

Free energy of reaction

 +  = ( • )

By formula: Na⁺ + He = (Na⁺ • He)

 +  = ( • )

By formula: K⁺ + He = (K⁺ • He)

(He⁺ • 2) +  = (He⁺ • 3)

By formula: (He⁺ • 2He) + He = (He⁺ • 3He)

Free energy of reaction

(He⁺ • 3) +  = (He⁺ • 4)

By formula: (He⁺ • 3He) + He = (He⁺ • 4He)

(He⁺ • 4) +  = (He⁺ • 5)

By formula: (He⁺ • 4He) + He = (He⁺ • 5He)

 +  = ( • )

By formula: N₂⁺ + He = (N₂⁺ • He)

He⁺ +  = (He⁺ • )

By formula: He⁺ + He = (He⁺ • He)

 +  = ( • )

By formula: Cs⁺ + He = (Cs⁺ • He)

HN₂⁺ +  = (HN₂⁺ • )

By formula: HN₂⁺ + He = (HN₂⁺ • He)

Ne⁺ +  = (Ne⁺ • )

By formula: Ne⁺ + He = (Ne⁺ • He)

Ar⁺ +  = (Ar⁺ • )

By formula: Ar⁺ + He = (Ar⁺ • He)

Gas phase ion energetics data

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

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

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

Data compiled as indicated in comments:
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
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

Ionization energy determinations

References

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

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

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]

Chase, 1998
Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

Gatland, 1984
Gatland, I.R., Swarms of Ions and Electrons in Gases, W. Lindinger, T. D. Mark and F. Howorka, eds. (Springer, New York, 1984, 1984, 44. [all data]

Gislason, 1984
Gislason, E.A., Quoted in I. R. Gatland in Swarms of Ions and Electrons in Gases, W. Lindinger, T. D. Mark and F. Howorka, eds. (Springer, New York, 1984, 1984, 44. [all data]

Viehland, 1984
Viehland, L.A., Interaction Potentials for Li+ - Rare - Gas Systems, Chem. Phys., 1984, 78, 2, 279, https://doi.org/10.1016/0301-0104(83)85114-3 . [all data]

Mason and Sharp, 1958
Mason, E.A.; Sharp, H.W., Mobility of gaseous lons in weak electric fields, Ann. Phys., 1958, 4, 3, 233, https://doi.org/10.1016/0003-4916(58)90049-6 . [all data]

Takebe, 1983
Takebe, M., The Generalized Mobility Curve for Alkali Ions in Rare Gases: Clustering Reactions and Mobility Curves, J. Chem. Phys., 1983, 78, 12, 7223, https://doi.org/10.1063/1.444763 . [all data]

Colonna-Romano and Keller, 1976
Colonna-Romano, L.M.; Keller, G.E., The Clustering of O2 and He to Li+, J. Chem. Phys., 1976, 64, 6, 2684, https://doi.org/10.1063/1.432522 . [all data]

Kemper, Hsu, et al., 1991
Kemper, P.R.; Hsu, M.T.; Bowers, M.T., Transition - Metal Ion - Rare Gas Clusters: Bond Strengths and Molecular Parameters for Co+(He/Ne)n, Ni+(He/Ne)n, and Cr+(He/Ne/Ar), J. Phys. Chem., 1991, 95, 26, 10600, https://doi.org/10.1021/j100179a022 . [all data]

Patterson, 1968
Patterson, P.L., Evidence of the Existence of an He3+ Ion, J. Chem. Phys., 1968, 48, 8, 3625, https://doi.org/10.1063/1.1669660 . [all data]

Gusinow, Gerber, et al., 1970
Gusinow, M.A.; Gerber, R.A.; Gerardo, J.B., He3+ and He4+ in 300K Helium Plasmas: Their Effect on Recombination Loss of Electrons, Phys. Rev. Lett., 1970, 25, 18, 1248, https://doi.org/10.1103/PhysRevLett.25.1248 . [all data]

Robson and Kumar, 1973
Robson, R.E.; Kumar, K., Mobility and Diffusion II. Dependence on Experimental Variables and Interaction Potential for Alkali Ions in Rare Gases, Aust. J. Phys., 1973, 26, 2, 187, https://doi.org/10.1071/PH730187 . [all data]

Hiraoka and Mori, 1990
Hiraoka, K.; Mori, T., Stability of Rare - Gas Cluster Ions, J. Chem. Phys., 1990, 92, 7, 4408, https://doi.org/10.1063/1.457751 . [all data]

Helm, 1976
Helm, H., The Mobilities and Equilibrium Reactions of Helium Ions in Helium at 77K, J. Phys. B, 1976, 9, 7, 1171, https://doi.org/10.1088/0022-3700/9/7/017 . [all data]

Bieske, Soliva, et al., 1990
Bieske, E.J.; Soliva, A.; Welker, M.A.; Maier, J.P., The B<---X Electronic Spectrum of N2+ He, J. Chem. Phys., 1990, 93, 6, 4477, https://doi.org/10.1063/1.458732 . [all data]

Miller, Tennyson, et al., 1988
Miller, S.; Tennyson, J.; Follmeg, B.; Rosmus, P.; Werner, H., Ab initio Investigation of the Bond Rovibrational States in the Electronic Ground State of HeN2+, J. Chem. Phys., 1988, 89, 4, 2178, https://doi.org/10.1063/1.455062 . [all data]

Dehmer and Pratt, 1982
Dehmer, P.M.; Pratt, S.T., Photoionization of ArKr, ArXe, and KrXe and bond dissociation energies of the rare gas dimer ions, J. Chem. Phys., 1982, 77, 4804. [all data]

Mittman and Weise, 1974
Mittman, H.U.; Weise, H.P., Scattering of Ions V. Elastic Scattering of the Symmetric Rare Gas Ion - Rare Gas Atom Systems, Z. Naturforsch., 1974, A29, 400. [all data]

Meuwly, Nizkorodov, et al., 1996
Meuwly, M.; Nizkorodov, S.A.; Maier, J.P.; Bieske, E.J., Mid-Infrared Spectra of He-HN2+ and He2-HN2+, J. Chem. Phys., 1996, 104, 11, 3876, https://doi.org/10.1063/1.471244 . [all data]

Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

Lide, 1992
Lide, D.R. (Editor), Ionization potentials of atoms and atomic ions in Handbook of Chem. and Phys., 1992, 10-211. [all data]

Wetzel, Baiocchi, et al., 1987
Wetzel, R.C.; Baiocchi, F.A.; Hayes, T.R.; Freund, R.S., Absolute cross sections for electron-impact ionization of the rare-gas atoms by the fast-neutral-beam method, Phys. Rev. A, 1987, 35, 559. [all data]

Kelly, 1987
Kelly, R.L., Atomic and ionic spectrum lines of hydrogen through kryton, J. Phys. Chem. Ref. Data, 1987, 16. [all data]

Moore, 1970
Moore, C.E., Ionization potentials and ionization limits derived from the analyses of optical spectra, Natl. Stand. Ref. Data Ser., (U.S. Natl. Bur. Stand.), 1970, 34, 1. [all data]

Kaneko, 1960
Kaneko, Y., Ionization efficiency curves for A⁺, Kr⁺, N₂⁺, and CO⁺ by electron impact, J. Phys. Soc. Japan, 1960, 16, 1587. [all data]

Weissler, Samson, et al., 1959
Weissler, G.L.; Samson, J.A.R.; Ogawa, M.; Cook, G.R., Photoionization analysis by mass spectroscopy, J. Opt. Soc. Am., 1959, 49, 338. [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, References

• Symbols used in this document:
  

  IE (evaluated)	Recommended ionization energy
  S°gas,1 bar	Entropy of gas at standard conditions (1 bar)
  T	Temperature
  ΔrG°	Free energy of reaction at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions
  ΔrS°	Entropy of reaction at standard conditions

• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
• The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database.
• Customer support for NIST Standard Reference Data products.