Magnesium dimer
- Formula: Mg2
- Molecular weight: 48.6100
- IUPAC Standard InChI: InChI=1S/2Mg
- IUPAC Standard InChIKey: HZZOEADXZLYIHG-UHFFFAOYSA-N
- CAS Registry Number: 29904-79-8
- Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
The 3d structure may be viewed using Java or Javascript. - Permanent link for this species. Use this link for bookmarking this species for future reference.
- Information on this page:
- Options:
Gas phase thermochemistry data
Go To: Top, Gas phase ion energetics data, Constants of diatomic molecules, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔfH°gas | 68.745 | kcal/mol | Review | Chase, 1998 | Data last reviewed in September, 1983 |
| Quantity | Value | Units | Method | Reference | Comment |
| S°gas,1 bar | 57.407 | cal/mol*K | Review | Chase, 1998 | Data last reviewed in September, 1983 |
Gas Phase Heat Capacity (Shomate Equation)
Cp° = 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
Cp = 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.
| Temperature (K) | 298. to 800. | 800. to 2000. | 2000. to 4000. | 4000. to 6000. |
|---|---|---|---|---|
| A | 5.129518 | 3.463385 | 163.2063 | -876.1759 |
| B | -0.586566 | 2.482696 | -113.0935 | 387.8848 |
| C | 0.764283 | -1.518289 | 28.62500 | -60.24570 |
| D | -0.344343 | 0.326733 | -2.287254 | 3.196631 |
| E | 0.070467 | 0.285968 | -113.3970 | 1587.345 |
| F | 67.47108 | 68.41157 | -146.6826 | 1973.150 |
| G | 64.15392 | 62.11042 | 115.0143 | 199.1150 |
| H | 68.74403 | 68.74403 | 68.74403 | 68.74403 |
| Reference | Chase, 1998 | Chase, 1998 | Chase, 1998 | Chase, 1998 |
| Comment | Data last reviewed in September, 1983 | Data last reviewed in September, 1983 | Data last reviewed in September, 1983 | Data last reviewed in September, 1983 |
Gas phase ion energetics data
Go To: Top, Gas phase thermochemistry data, Constants of diatomic molecules, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data evaluated by: Edward P. Hunter and Sharon G. Lias
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| Proton affinity (review) | 220. | kcal/mol | N/A | Hunter and Lias, 1998 | |
| Quantity | Value | Units | Method | Reference | Comment |
| Gas basicity | 211.9 | kcal/mol | N/A | Hunter and Lias, 1998 |
Constants of diatomic molecules
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: Klaus P. Huber and Gerhard H. Herzberg
Data collected through March, 1977
| Symbol | Meaning |
|---|---|
| State | electronic state and / or symmetry symbol |
| Te | minimum electronic energy (cm-1) |
| ωe | vibrational constant – first term (cm-1) |
| ωexe | vibrational constant – second term (cm-1) |
| ωeye | vibrational constant – third term (cm-1) |
| Be | rotational constant in equilibrium position (cm-1) |
| αe | rotational constant – first term (cm-1) |
| γe | rotation-vibration interaction constant (cm-1) |
| De | centrifugal distortion constant (cm-1) |
| βe | rotational constant – first term, centrifugal force (cm-1) |
| re | internuclear distance (Å) |
| Trans. | observed transition(s) corresponding to electronic state |
| ν00 | position of 0-0 band (units noted in table) |
| State | Te | ωe | ωexe | ωeye | Be | αe | γe | De | βe | re | Trans. | ν00 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| C (1Σu+) | [0.1354] 1 | [0.4E-6] 1 | [3.222] 1 | C ← X V | [38048.8] 1 Z | |||||||
| ↳Balfour and Douglas, 1970 | ||||||||||||
| B (1Πu) 2 | B ← X | |||||||||||
| ↳Weniger, 1964; Edelhoff, Kusch, et al., 1968; Balfour and Douglas, 1970 | ||||||||||||
| A 1Σu+ | 26068.76 | 190.615 Z | 1.1456 3 | 0.001772 | 0.147999 | 0.0013164 | 0.1474E-5 | 0.334E-6 4 | 3.08186 | A ↔ X 5 6 V | 26138.63 Z | |
| ↳Hamada, 1931; missing citation; missing citation | ||||||||||||
| X 1Σg+ | 0 | 51.121 Z | 1.645 7 | 0.01624 | 0.09287 | 0.003776 8 | 1.217E-6 9 | 3.8905 | 10 11 | |||
Notes
| 1 | Lowest observed level, vibrational numbering uncertain. |
| 2 | Continuous absorption and diffusion bands, 35050 - 37600 cm-1, tentatively assigned to the 1Π state arising from 1S + 1P. |
| 3 | Vibrational numbering established by the observed 24Mg2 - 26Mg2 isotope shifts Balfour and Douglas, 1970. |
| 4 | He = +0.23E-11. |
| 5 | Franck-Condon factors and their dependence on rotation Balfour and Whitlock, 1972. |
| 6 | Observed in Kr and Xe matrices by Brewer and Wang, 1971 and in Ne, Ar, N2 matrices by Knight and Ebener, 1976. The same authors also observe other absorptions probably related to B-X and C-X in the gas. |
| 7 | ωeze = -0.000611. |
| 8 | missing note |
| 9 | -0.031E-6(v+1/2) + 0.021E-6(v+1/2)2; Hv = -0.26E-10 - 0.085E- 10(v+1/2). |
| 10 | Term values of ro-vibrational levels, RKR potential functions Balfour and Douglas, 1970, Li and Stwalley, 1973. For other potential functions see Brett and Chan, 1972, Muhlhausen and Konowalow, 1975. |
| 11 | Long range potential studied by Stwalley, 1971, Li and Stwalley, 1973. |
| 12 | From the convergence of the vibrational levels v=0...12 of the ground state Balfour and Douglas, 1970 including the slight extension (v=13) and correction by Li and Stwalley, 1973. |
| 13 | 0.0001068(v+1/2)2 - 0.00000968(v+1/2)3. |
References
Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Constants of diatomic molecules, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Chase, 1998
Chase, M.W., Jr.,
NIST-JANAF Themochemical Tables, Fourth Edition,
J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [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]
Balfour and Douglas, 1970
Balfour, W.J.; Douglas, A.E.,
Absorption spectrum of the Mg2 molecule,
Can. J. Phys., 1970, 48, 901. [all data]
Weniger, 1964
Weniger, S.,
Spectre d'absorption de la vapeur de magnesium dans l'ultra-violet proche,
J. Phys. (Paris), 1964, 25, 946. [all data]
Edelhoff, Kusch, et al., 1968
Edelhoff, B.; Kusch, H.J.; Lochte-Holtgreven, W.,
Untersuchung der absorption in der umgebung der MgI-resonanzlinie λ = 2852 Å im kingschen ofen,
Rev. Roum. Phys., 1968, 13, 2, 125-135. [all data]
Hamada, 1931
Hamada, H.,
III. On the molecular spectra of mercury, zinc, cadmium, magnesium, and thallium,
Philos. Mag., 1931, 12, 50. [all data]
Balfour and Whitlock, 1972
Balfour, W.J.; Whitlock, R.F.,
Rotational dependence of Franck-Condon factors in the A1Σu+ ← X1Σg+ system of 24Mg2,
Can. J. Phys., 1972, 50, 1648. [all data]
Brewer and Wang, 1971
Brewer, L.; Wang, J.L.-F.,
Absorption spectrum of the Mg2 molecule in solid rare gases,
J. Mol. Spectrosc., 1971, 40, 95. [all data]
Knight and Ebener, 1976
Knight, L.B.; Ebener, M.A.,
Matrix isolation of Mg2 and Mgn molecules in neon, argon, and nitrogen hosts,
J. Mol. Spectrosc., 1976, 61, 412. [all data]
Li and Stwalley, 1973
Li, K.C.; Stwalley, W.C.,
Vibrational levels near dissociation in Mg2 and long-range forces,
J. Chem. Phys., 1973, 59, 4423. [all data]
Brett and Chan, 1972
Brett, A.C.; Chan, C.,
The Mg2 potential: a curve fitting study,
Can. J. Phys., 1972, 50, 1587. [all data]
Muhlhausen and Konowalow, 1975
Muhlhausen, C.W.; Konowalow, D.D.,
Hybrid potentials for the 1Σg+ state of Mg2,
Chem. Phys., 1975, 7, 143. [all data]
Stwalley, 1971
Stwalley, W.C.,
Polarizability and long-range interactions of magnesium atoms,
J. Chem. Phys., 1971, 54, 4517. [all data]
Notes
Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Constants of diatomic molecules, References
- Symbols used in this document:
S°gas,1 bar Entropy of gas at standard conditions (1 bar) ΔfH°gas Enthalpy of formation of gas 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.