silicon

Formula: Si
Molecular weight: 28.0855
IUPAC Standard InChI: InChI=1S/Si
IUPAC Standard InChIKey: XUIMIQQOPSSXEZ-UHFFFAOYSA-N
CAS Registry Number: 7440-21-3
Chemical structure:
This structure is also available as a 2d Mol file
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Phase change data

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Antoine Equation Parameters

log₁₀(P) = A − (B / (T + C))
P = vapor pressure (atm)
T = temperature (K)

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Temperature (K)	A	B	C	Reference	Comment
1997. to 2560.	9.55865	23308.848	-123.133	Stull, 1947	Coefficents calculated by NIST from author's data.

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

(Si₄^- • 4294967295 silicon ) + silicon = Si₄^-

By formula: (Si₄^- • 4294967295Si) + Si = Si₄^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	98.2 ± 6.9	kcal/mol	N/A	Nakajima, Taguwa, et al., 1995	gas phase; Vertical Detachment Energy: 2.15±0.04 eV.

(CAS Reg. No. 11080-58-3 • 4294967295 silicon ) + silicon = CAS Reg. No. 11080-58-3

By formula: (CAS Reg. No. 11080-58-3 • 4294967295Si) + Si = CAS Reg. No. 11080-58-3

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	72.8 ± 3.3	kcal/mol	N/A	Kawamata, Neigishi, et al., 1996	gas phase; Vertical Detachment Energy: 0.81±0.05 eV.

(CAS Reg. No. 106389-62-2 • 4294967295 silicon ) + silicon = CAS Reg. No. 106389-62-2

By formula: (CAS Reg. No. 106389-62-2 • 4294967295Si) + Si = CAS Reg. No. 106389-62-2

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	112.2 ± 8.2	kcal/mol	N/A	Xu, Taylor, et al., 1998	gas phase

(Si₃^- • 4294967295 silicon ) + silicon = Si₃^-

By formula: (Si₃^- • 4294967295Si) + Si = Si₃^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	4.6 ± 4.3	kcal/mol	N/A	Arnold and Neumark, 1994	gas phase

(CAS Reg. No. 64236-73-3 • 4294967295 silicon ) + silicon = CAS Reg. No. 64236-73-3

By formula: (CAS Reg. No. 64236-73-3 • 4294967295Si) + Si = CAS Reg. No. 64236-73-3

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	124.9 ± 4.0	kcal/mol	N/A	Nimlos, Harding, et al., 1987	gas phase

(HSi^- • 4294967295 silicon ) + silicon = HSi^-

By formula: (HSi^- • 4294967295Si) + Si = HSi^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	83.6 ± 3.2	kcal/mol	N/A	Kasdan, Herbst, et al., 1975	gas phase

Gas phase ion energetics data

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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
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron
B - John E. Bartmess

View reactions leading to Si⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	8.15169	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	200.	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	194.6	kcal/mol	N/A	Hunter and Lias, 1998	HL

Electron affinity determinations

EA (eV)	Method	Reference	Comment
1.389517 ± 0.000044	LPD	Blondel, Chaibi, et al., 2005	(28)Si: 1.3895213(13) eV; revised analysis of Blondel, Delsart, et al., 2001; B
1.38952	LPD	Blondel, Delsart, et al., 2001	Given: 1.3895220(24) eV, or 11207.252(18) cm-1; B
1.389517 ± 0.000044	LPD	Scheer, Bilodeau, et al., 1998	Given: 1.389521(20) eV; B
1.3850 ± 0.0050	LPES	Kasdan, Herbst, et al., 1975	B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
8.15169	EVAL	Lide, 1992	LL
8.152	S	Kelly, 1987	LBLHLM
8.2 ± 0.5	EI	Muenow, 1974	LLK
8.15166 ± 0.00003	S	Brown, Tilford, et al., 1974	LLK
8.1 ± 0.5	EI	Guido and Gigli, 1973	LLK
8.5 ± 0.5	EI	Hildenbrand, 1972	LLK
8.15169	S	Moore, 1970	RDSH

References

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Stull, 1947
Stull, Daniel R., Vapor Pressure of Pure Substances. Organic and Inorganic Compounds, Ind. Eng. Chem., 1947, 39, 4, 517-540, https://doi.org/10.1021/ie50448a022 . [all data]

Nakajima, Taguwa, et al., 1995
Nakajima, A.; Taguwa, T.; Nakao, K.; Gomei, M.; Kishi, R.; Iwata, S.; Kaya, K., Photoelectron Spectroscopy of silicon-carbon cluster Anions (SinCm-), J. Chem. Phys., 1995, 103, 6, 2050, https://doi.org/10.1063/1.469731 . [all data]

Kawamata, Neigishi, et al., 1996
Kawamata, H.; Neigishi, Y.; Kishi, R.; Iwata, S.; Nakajima, A.; Kaya, K., Photoelectron Spectroscopy of Silicon-Fluorine Binary Cluster Anions (SinFm-), J. Chem. Phys., 1996, 105, 13, 5369, https://doi.org/10.1063/1.472377 . [all data]

Xu, Taylor, et al., 1998
Xu, C.S.; Taylor, T.R.; Burton, G.R.; Neumark, D.M., Vibrationally reserved photoelectron spectroscopy of silicon cluster anions Si-n(-) (n=3-7), J. Chem. Phys., 1998, 108, 4, 1395-1406, https://doi.org/10.1063/1.475511 . [all data]

Arnold and Neumark, 1994
Arnold, C.C.; Neumark, D.M., Threshold Photodetachment Zero-Electron Kinetic Energy Spectroscopy of Si-3(-), J. Chem. Phys., 1994, 100, 3, 1797, https://doi.org/10.1063/1.466532 . [all data]

Nimlos, Harding, et al., 1987
Nimlos, M.R.; Harding, L.B.; Ellison, G.B., The Electronic States of Si₂ and Si₂^- as Revealed by Photoelectron Spectroscopy, J. Chem. Phys., 1987, 87, 9, 5116, https://doi.org/10.1063/1.453679 . [all data]

Kasdan, Herbst, et al., 1975
Kasdan, A.; Herbst, E.; Lineberger, W.C., Laser photoelectron spectrometry of the negative ions of silicon and its hydrides, J. Chem. Phys., 1975, 62, 541. [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]

Blondel, Chaibi, et al., 2005
Blondel, C.; Chaibi, W.; Delsart, C.; Drag, C.; Goldfarb, F.; Kroger, S., The electron affinities of O, Si, and S revisited with the photodetachment microscope, Eur. Phys. J. D, 2005, 33, 3, 335-342, https://doi.org/10.1140/epjd/e2005-00069-9 . [all data]

Blondel, Delsart, et al., 2001
Blondel, C.; Delsart, C.; Goldfarb, F., Electron spectrometry at the mu eV level and the electron affinities of Si and F, J. Phys. B: Atom. Mol. Opt. Phys., 2001, 34, 9, L281-L288, https://doi.org/10.1088/0953-4075/34/9/101 . [all data]

Scheer, Bilodeau, et al., 1998
Scheer, M.; Bilodeau, R.C.; Brodie, C.A.; Haugen, H.K., Systematic study of the stable states of C-, Si-, Ge-, and Sn- via infrared laser spectroscopy, Phys. Rev. A, 1998, 58, 4, 2844-2856, https://doi.org/10.1103/PhysRevA.58.2844 . [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]

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

Muenow, 1974
Muenow, D.W., Mass spectrometric determination of the heats of formation and atomization energies of the molecules Ge₂N and GeSiN, J. Chem. Phys., 1974, 60, 3382. [all data]

Brown, Tilford, et al., 1974
Brown, C.M.; Tilford, S.G.; Tousey, R.; Ginter, M.L., Absorption spectrum of Si I between 1500 and 1900 A, J. Opt. Soc. Am., 1974, 64, 1665. [all data]

Guido and Gigli, 1973
Guido, M.; Gigli, G., Mass spectrometric study of the CeSiC molecules, J. Chem. Phys., 1973, 59, 3437. [all data]

Hildenbrand, 1972
Hildenbrand, D.L., The gaseous equilibrium Ge + SiO = GeO + Si and the dissociation energy of SiO, High Temp. Sci., 1972, 4, 244. [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]

Notes

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Symbols used in this document:

EA Electron affinity

IE (evaluated) Recommended ionization energy

Δ_rH° Enthalpy of reaction at standard conditions
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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EA	Electron affinity
IE (evaluated)	Recommended ionization energy
Δ_rH°	Enthalpy of reaction at standard conditions