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:
  • Phase change data
  • Henry's Law data
  • Gas phase ion energetics data
  • References
  • Notes
• Other data available:
  • Gas phase thermochemistry data
  • Reaction thermochemistry 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)
  • Computational Chemistry Comparison and Benchmark Database
  • Gas Phase Kinetics Database
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Phase change data

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

Data compiled by: Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director

Henry's Law data

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

Data compiled by: Rolf Sander

Henry's Law constant (water solution)

k_H(T) = k°_H exp(d(ln(k_H))/d(1/T) ((1/T) - 1/(298.15 K)))
k°_H = Henry's law constant for solubility in water at 298.15 K (mol/(kg*bar))
d(ln(k_H))/d(1/T) = Temperature dependence constant (K)

Gas phase ion energetics data

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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

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

Angus, de Reuck, et al., 1977
Angus, S.; de Reuck, K.M.; McCarty, R.D., International Thermodynamic Tables of the Fluid State - 4 Helium, Pergamon, New York, 1977. [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, Phase change data, Henry's Law data, Gas phase ion energetics data, References

• Symbols used in this document:
  

  IE (evaluated)	Recommended ionization energy
  Pc	Critical pressure
  Tc	Critical temperature
  d(ln(kH))/d(1/T)	Temperature dependence parameter for Henry's Law constant
  k°H	Henry's Law constant at 298.15K
  ρc	Critical density

• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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