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Molecular Data

Bond lengths, bond angles, dissociation energies, vibrational frequencies, dipole moments, and polarizabilities for common molecules.

Source: NIST CCCBDB; JANAF Thermochemical Tables

Diatomic Molecule Constants

H₂ (hydrogen)
Bond length re0.741 44 ± 0.000 01Å
Dissociation energy De4.7483 ± 0.0001eV (458.0 kJ/mol)
Vibrational frequency ωe4 401.21 cm⁻¹
Rotational constant Be60.853 cm⁻¹
D₂ (deuterium)
Bond length re0.741 52 Å
Dissociation energy De4.7561 eV
Vibrational frequency ωe3 115.50 cm⁻¹
Rotational constant Be30.444 cm⁻¹
N₂ (nitrogen)
Bond length re1.097 68 ± 0.000 01Å
Dissociation energy De9.7586 ± 0.0010eV (941.7 kJ/mol)
Vibrational frequency ωe2 358.57 cm⁻¹
Rotational constant Be1.9983 cm⁻¹
O₂ (oxygen)
Bond length re1.207 52 ± 0.000 01Å
Dissociation energy De5.1157 ± 0.0010eV (493.7 kJ/mol)
Vibrational frequency ωe1 580.19 cm⁻¹
Rotational constant Be1.4457 cm⁻¹
Electronic ground state³Σg⁻ (triplet, paramagnetic)
F₂ (fluorine)
Bond length re1.411 90 ± 0.000 05Å
Dissociation energy De1.602 ± 0.002eV (154.6 kJ/mol)
Vibrational frequency ωe916.64 cm⁻¹
Cl₂ (chlorine)
Bond length re1.987 9 ± 0.000 1Å
Dissociation energy De2.4783 ± 0.0010eV (239.2 kJ/mol)
Vibrational frequency ωe559.72 cm⁻¹
Br₂ (bromine)
Bond length re2.2810 ± 0.0001Å
Dissociation energy De1.971 ± 0.002eV (190.1 kJ/mol)
Vibrational frequency ωe325.32 cm⁻¹
I₂ (iodine)
Bond length re2.6663 ± 0.0001Å
Dissociation energy De1.5724 ± 0.0010eV (151.7 kJ/mol)
Vibrational frequency ωe214.50 cm⁻¹
HF (hydrogen fluoride)
Bond length re0.916 80 ± 0.000 05Å
Dissociation energy De5.869 ± 0.001eV (566.3 kJ/mol)
Vibrational frequency ωe4 138.32 cm⁻¹
Rotational constant Be20.956 cm⁻¹
Electric dipole moment μ1.826 2 ± 0.000 5D
HCl (hydrogen chloride)
Bond length re1.274 55 ± 0.000 01Å
Dissociation energy De4.4338 ± 0.0010eV (427.8 kJ/mol)
Vibrational frequency ωe2 990.95 cm⁻¹
Rotational constant Be10.5934 cm⁻¹
Electric dipole moment μ1.084 9 ± 0.000 5D
HBr (hydrogen bromide)
Bond length re1.414 44 ± 0.000 02Å
Dissociation energy De3.757 ± 0.002eV (362.4 kJ/mol)
Vibrational frequency ωe2 648.97 cm⁻¹
Rotational constant Be8.4649 cm⁻¹
Electric dipole moment μ0.827 2 ± 0.000 6D
HI (hydrogen iodide)
Bond length re1.609 16 ± 0.000 01Å
Dissociation energy De3.064 ± 0.001eV (295.7 kJ/mol)
Vibrational frequency ωe2 309.01 cm⁻¹
Rotational constant Be6.5117 cm⁻¹
Electric dipole moment μ0.448 1 ± 0.000 2D
CO (carbon monoxide)
Bond length re1.128 32 ± 0.000 01Å
Dissociation energy De11.108 ± 0.002eV (1 071.8 kJ/mol)
Vibrational frequency ωe2 169.81 cm⁻¹
Rotational constant Be1.9225 cm⁻¹
Electric dipole moment μ0.1098 ± 0.0002D (C⁻O⁺ polarity)
NO (nitric oxide)
Bond length re1.150 77 ± 0.000 01Å
Dissociation energy De6.487 ± 0.001eV (625.8 kJ/mol)
Vibrational frequency ωe1 904.20 cm⁻¹
Electronic ground state²Π (doublet, paramagnetic)
Electric dipole moment μ0.1591 ± 0.0002D
OH (hydroxyl radical)
Bond length re0.969 66 ± 0.000 02Å
Dissociation energy De4.399 ± 0.001eV (424.4 kJ/mol)
Vibrational frequency ωe3 737.76 cm⁻¹
Electric dipole moment μ1.655 ± 0.001D
Li₂ (dilithium)
Bond length re2.6729 ± 0.0002Å
Dissociation energy De1.028 5 ± 0.000 1eV
Vibrational frequency ωe351.43 cm⁻¹

Polyatomic Bond Lengths & Angles

H₂O (water, gas phase)
O–H bond length0.9572 ± 0.0003Å
H–O–H bond angle104.52 ± 0.05°
GeometryC₂v (bent)
H₂O₂ (hydrogen peroxide, gas)
O–O bond length1.4523 ± 0.0003Å
O–H bond length0.9655 ± 0.0003Å
H–O–O angle101.9 ± 0.3°
Dihedral angle119.8 ± 0.5°
NH₃ (ammonia, gas)
N–H bond length1.0124 ± 0.0002Å
H–N–H bond angle106.67 ± 0.05°
GeometryC₃v (trigonal pyramidal)
CH₄ (methane)
C–H bond length1.087 ± 0.001Å
H–C–H bond angle109.471 ° (exact tetrahedral)exact
GeometryTd (tetrahedral)
CO₂ (carbon dioxide)
C=O bond length1.1600 ± 0.0002Å
O=C=O bond angle180 ° (linear, D∞h)exact
SO₂ (sulfur dioxide)
S=O bond length1.4308 ± 0.0005Å
O=S=O bond angle119.33 ± 0.05°
GeometryC₂v (bent)
SO₃ (sulfur trioxide)
S=O bond length1.4198 ± 0.0003Å
O=S=O bond angle120.0 ° (D₃h, planar)exact
NO₂ (nitrogen dioxide)
N=O bond length1.1946 ± 0.0002Å
O–N–O bond angle134.10 ± 0.05°
HCN (hydrogen cyanide)
C≡N bond length1.1532 ± 0.0002Å
C–H bond length1.0655 ± 0.0002Å
GeometryC∞v (linear)
H₂CO (formaldehyde)
C=O bond length1.2078 ± 0.0002Å
C–H bond length1.1161 ± 0.0003Å
H–C–H bond angle116.52 ± 0.05°
C₂H₂ (acetylene)
C≡C bond length1.2033 ± 0.0002Å
C–H bond length1.0605 ± 0.0003Å
GeometryD∞h (linear)
C₂H₄ (ethylene)
C=C bond length1.3394 ± 0.0002Å
C–H bond length1.0824 ± 0.0005Å
H–C=C bond angle121.3 ± 0.3°
C₂H₆ (ethane)
C–C bond length1.5351 ± 0.0005Å
C–H bond length1.0940 ± 0.0005Å
H–C–C bond angle111.2 ± 0.3°
C₆H₆ (benzene)
C–C bond length (aromatic)1.3961 ± 0.0002Å
C–H bond length1.0830 ± 0.0005Å
GeometryD₆h (planar hexagonal)
N₂O (nitrous oxide)
N≡N bond length1.1280 ± 0.0001Å
N=O bond length1.1841 ± 0.0001Å
GeometryC∞v (linear: N–N–O)
OCS (carbonyl sulfide)
C=O bond length1.1561 ± 0.0001Å
C=S bond length1.5601 ± 0.0001Å
GeometryC∞v (linear: O–C–S)
H₂S (hydrogen sulfide)
S–H bond length1.3356 ± 0.0003Å
H–S–H bond angle92.11 ± 0.05°
PH₃ (phosphine)
P–H bond length1.4200 ± 0.0005Å
H–P–H bond angle93.36 ± 0.05°

Electric Dipole Moments

Electric Dipole Moment μ (gas phase)
H₂ (hydrogen)0 D (homonuclear, zero by symmetry)exact
N₂ (nitrogen)0 D (homonuclear, zero by symmetry)exact
O₂ (oxygen)0 D (homonuclear, zero by symmetry)exact
Cl₂ (chlorine)0 D (homonuclear, zero by symmetry)exact
CO₂ (carbon dioxide)0 D (linear, D∞h symmetry)exact
CH₄ (methane)0 D (Td symmetry)exact
C₂H₄ (ethylene)0 D (D₂h symmetry)exact
C₂H₂ (acetylene)0 D (D∞h symmetry)exact
C₆H₆ (benzene)0 D (D₆h symmetry)exact
CO (carbon monoxide)0.1098 ± 0.0002D (C⁻O⁺ polarity)
NO (nitric oxide)0.1591 ± 0.0002D
H₂S (hydrogen sulfide)0.9733 ± 0.0003D
HI (hydrogen iodide)0.4481 ± 0.0002D
HBr (hydrogen bromide)0.8272 ± 0.0006D
NF₃ (nitrogen trifluoride)0.2346 ± 0.0003D
PH₃ (phosphine)0.5740 ± 0.0003D
NO₂ (nitrogen dioxide)0.3160 ± 0.0010D
N₂O (nitrous oxide)0.1608 ± 0.0006D
SO₂ (sulfur dioxide)1.6330 ± 0.0010D
HCl (hydrogen chloride)1.0849 ± 0.0005D
OH (hydroxyl radical)1.6550 ± 0.0010D
NH₃ (ammonia)1.4718 ± 0.0002D
H₂O (water)1.8546 ± 0.0004D
HF (hydrogen fluoride)1.8262 ± 0.0005D
CH₃Cl (chloromethane)1.8930 ± 0.0020D
CH₃F (fluoromethane)1.8580 ± 0.0020D
CH₃OH (methanol)1.6990 ± 0.0020D
H₂CO (formaldehyde)2.3321 ± 0.0003D
HCN (hydrogen cyanide)2.9851 ± 0.0002D
CH₃CN (acetonitrile)3.9240 ± 0.0030D
Debye unit (1 D)
Value in SI3.335 641 × 10⁻³⁰ C·m

Molecular Polarizabilities

Electric Dipole Polarizability α (static)
He (helium)0.2051 ų
Ne (neon)0.3946 ų
Ar (argon)1.6411 ų
Kr (krypton)2.484 ų
Xe (xenon)4.044 ų
H₂ (hydrogen)0.787 ų
N₂ (nitrogen)1.740 ų
O₂ (oxygen)1.562 ų
F₂ (fluorine)1.200 ų
Cl₂ (chlorine)4.617 ų
HF (hydrogen fluoride)0.820 ų
HCl (hydrogen chloride)2.515 ų
HBr (hydrogen bromide)3.488 ų
HI (hydrogen iodide)5.430 ų
CO (carbon monoxide)1.953 ų
CO₂ (carbon dioxide)2.911 ų
H₂O (water)1.501 ų
NH₃ (ammonia)2.103 ų
SO₂ (sulfur dioxide)3.882 ų
CH₄ (methane)2.593 ų
C₂H₂ (acetylene)3.487 ų
C₂H₄ (ethylene)4.252 ų
C₂H₆ (ethane)4.474 ų
C₆H₆ (benzene)10.00 ų
HCN (hydrogen cyanide)2.593 ų
Polarizability unit: 1 ų = 1 ų
Value in SI1.112 650 × 10⁻³⁰ C² s² kg⁻¹ (= 4πε₀ × 10⁻³⁰ m³)

Standard Enthalpies of Formation ΔfH° (298.15 K)

ΔfH° — Elements in standard state
H₂(g)0 kJ mol⁻¹exact
N₂(g)0 kJ mol⁻¹exact
O₂(g)0 kJ mol⁻¹exact
C(graphite)0 kJ mol⁻¹exact
S(rhombic)0 kJ mol⁻¹exact
ΔfH° — Atoms & Radicals (gas phase)
H(g)+218.00 ± 0.01kJ mol⁻¹
O(g)+249.18 ± 0.10kJ mol⁻¹
N(g)+472.68 ± 0.10kJ mol⁻¹
C(g)+716.68 ± 0.45kJ mol⁻¹
F(g)+79.38 ± 0.30kJ mol⁻¹
Cl(g)+121.30 ± 0.06kJ mol⁻¹
Br(g)+111.87 ± 0.12kJ mol⁻¹
I(g)+106.76 ± 0.04kJ mol⁻¹
OH(g)+39.00 ± 0.20kJ mol⁻¹
ΔfH° — Hydrogen Compounds
H₂O(g)−241.826 ± 0.040kJ mol⁻¹
H₂O(l)−285.830 ± 0.040kJ mol⁻¹
H₂O₂(l)−187.780 ± 0.080kJ mol⁻¹
HF(g)−273.300 ± 0.700kJ mol⁻¹
HCl(g)−92.310 ± 0.100kJ mol⁻¹
HBr(g)−36.290 ± 0.160kJ mol⁻¹
HI(g)+26.500 ± 0.100kJ mol⁻¹
H₂S(g)−20.600 ± 0.500kJ mol⁻¹
ΔfH° — Nitrogen Compounds
NH₃(g)−46.110 ± 0.200kJ mol⁻¹
NO(g)+90.290 ± 0.180kJ mol⁻¹
NO₂(g)+33.180 ± 0.800kJ mol⁻¹
N₂O(g)+82.050 ± 0.300kJ mol⁻¹
N₂O₄(g)+11.100 ± 0.800kJ mol⁻¹
HNO₃(l)−174.100 ± 0.600kJ mol⁻¹
ΔfH° — Carbon Compounds
CO(g)−110.527 ± 0.017kJ mol⁻¹
CO₂(g)−393.509 ± 0.013kJ mol⁻¹
HCN(g)+135.100 ± 0.700kJ mol⁻¹
CH₄(g)−74.600 ± 0.300kJ mol⁻¹
C₂H₂(g)+226.730 ± 0.800kJ mol⁻¹
C₂H₄(g)+52.400 ± 0.500kJ mol⁻¹
C₂H₆(g)−84.000 ± 0.300kJ mol⁻¹
C₃H₈(g) propane−103.800 ± 0.600kJ mol⁻¹
H₂CO(g)−108.600 ± 0.500kJ mol⁻¹
CH₃OH(l)−239.200 ± 0.400kJ mol⁻¹
C₂H₅OH(l)−277.700 ± 0.700kJ mol⁻¹
C₆H₆(l) benzene+49.000 ± 0.900kJ mol⁻¹
C(diamond)+1.895 ± 0.003kJ mol⁻¹
ΔfH° — Sulfur Compounds
SO₂(g)−296.830 ± 0.200kJ mol⁻¹
SO₃(g)−395.720 ± 0.650kJ mol⁻¹
H₂SO₄(l)−813.989 ± 0.400kJ mol⁻¹
ΔfH° — Other
O₃(g) ozone+142.670 ± 0.800kJ mol⁻¹
C(fullerene C₆₀, s)+2340 ± 30kJ mol⁻¹

Standard Enthalpies of Combustion ΔcH° (298.15 K)

ΔcH° (products: CO₂(g), H₂O(l))
H₂(g)−285.8 kJ mol⁻¹
C(graphite)−393.5 kJ mol⁻¹
CO(g)−283.0 kJ mol⁻¹
CH₄(g) methane−890.4 kJ mol⁻¹
C₂H₂(g) acetylene−1 301.1 kJ mol⁻¹
C₂H₄(g) ethylene−1 410.9 kJ mol⁻¹
C₂H₆(g) ethane−1 559.8 kJ mol⁻¹
C₃H₈(g) propane−2 220.0 kJ mol⁻¹
C₄H₁₀(g) n-butane−2 878.5 kJ mol⁻¹
C₆H₆(l) benzene−3 267.4 kJ mol⁻¹
C₈H₁₈(l) octane (gasoline representative)−5 471 kJ mol⁻¹
CH₃OH(l) methanol−726.5 kJ mol⁻¹
C₂H₅OH(l) ethanol−1 366.8 kJ mol⁻¹
C₁₂H₂₂O₁₁(s) sucrose−5 640.9 kJ mol⁻¹
C₆H₁₂O₆(s) glucose−2 803.0 kJ mol⁻¹

Fundamental Vibrational Frequencies

H₂O (3 modes, C₂v)
ν₁ symmetric O–H stretch (A₁)3 657.05 cm⁻¹
ν₂ H–O–H bending (A₁)1 594.59 cm⁻¹
ν₃ asymmetric O–H stretch (B₁)3 755.79 cm⁻¹
All modes IR activeYes (C₂v has no IR-inactive modes)
CO₂ (4 modes, D∞h)
ν₁ symmetric C=O stretch (Σg⁺, IR inactive)1 388.2 cm⁻¹
ν₂ bending (Πu, doubly degenerate, IR active)667.4 cm⁻¹
ν₃ asymmetric C=O stretch (Σu⁺, IR active)2 349.1 cm⁻¹
Mutual exclusion rule appliesIR and Raman active modes are mutually exclusive
NH₃ (6 modes, C₃v)
ν₁ symmetric N–H stretch (A₁)3 336.2 cm⁻¹
ν₂ umbrella inversion (A₁)950.0 cm⁻¹
ν₃ asymmetric N–H stretch (E, doubly degenerate)3 443.8 cm⁻¹
ν₄ asymmetric bending (E, doubly degenerate)1 626.8 cm⁻¹
CH₄ (9 modes, Td)
ν₁ symmetric C–H stretch (A₁, Raman only)2 916.5 cm⁻¹
ν₂ bending (E, Raman only)1 534.0 cm⁻¹
ν₃ asymmetric C–H stretch (F₂, IR + Raman)3 019.0 cm⁻¹
ν₄ bending (F₂, IR + Raman)1 306.2 cm⁻¹
HCN (linear, 4 modes)
ν₁ C–H stretch (σ, IR active)3 311.5 cm⁻¹
ν₂ bending (π, doubly degenerate, IR active)713.5 cm⁻¹
ν₃ C≡N stretch (σ, IR active)2 096.8 cm⁻¹
SO₂ (3 modes, C₂v)
ν₁ symmetric S=O stretch (A₁)1 151.4 cm⁻¹
ν₂ bending (A₁)517.7 cm⁻¹
ν₃ asymmetric S=O stretch (B₁)1 361.8 cm⁻¹
Characteristic IR Group Frequencies
O–H stretch (alcohol, free)3 580–3 650 cm⁻¹
O–H stretch (H-bonded)3 200–3 550 cm⁻¹
N–H stretch (amine)3 300–3 500 cm⁻¹
C–H stretch (alkane)2 850–2 960 cm⁻¹
C≡N stretch (nitrile)2 200–2 260 cm⁻¹
C≡C stretch (alkyne)2 100–2 260 cm⁻¹
C=O stretch (aldehyde/ketone)1 700–1 750 cm⁻¹
C=O stretch (carboxylic acid)1 700–1 725 cm⁻¹
C=O stretch (ester)1 735–1 750 cm⁻¹
C=C stretch (alkene)1 620–1 680 cm⁻¹
C=C stretch (aromatic)1 450–1 600 cm⁻¹
C–O stretch (ether/alcohol)1 000–1 300 cm⁻¹
C–Cl stretch600–800 cm⁻¹

Physical Properties of Molecular Compounds

Helium (He)
Boiling point4.222 K (does not solidify at 1 atm)
Neon (Ne)
Melting / boiling point24.56 / 27.07 K
Argon (Ar)
Melting / boiling point83.80 / 87.30 K
Krypton (Kr)
Melting / boiling point115.79 / 119.93 K
Xenon (Xe)
Melting / boiling point161.4 / 165.13 K
H₂ (hydrogen)
Melting / boiling point13.99 / 20.27 K
Critical point (Tc, Pc)33.14 K, 1.296 MPa
N₂ (nitrogen)
Melting / boiling point63.15 / 77.36 K
Critical point (Tc, Pc)126.19 K, 3.390 MPa
O₂ (oxygen)
Melting / boiling point54.36 / 90.19 K
Critical point (Tc, Pc)154.60 K, 5.046 MPa
F₂ (fluorine)
Melting / boiling point53.48 / 85.03 K
Cl₂ (chlorine)
Melting / boiling point171.65 / 239.11 K
HF (hydrogen fluoride)
Melting / boiling point189.60 / 292.67 K
HCl (hydrogen chloride)
Melting / boiling point158.97 / 188.12 K
HBr (hydrogen bromide)
Melting / boiling point186.30 / 206.43 K
HI (hydrogen iodide)
Melting / boiling point222.38 / 237.60 K
NH₃ (ammonia)
Melting / boiling point195.40 / 239.82 K
Critical point (Tc, Pc)405.56 K, 11.357 MPa
H₂O (water)
Melting point (1 atm)273.150 K (0.000 °C)exact
Boiling point (1 atm)373.124 ± 0.010K (99.974 °C)
Triple point273.1600 ± 0.0001K, 611.73 Pa
Critical point (Tc, Pc)647.10 K, 22.064 MPa
Density (4 °C)999.972 kg m⁻³
Heat of vaporization (100 °C)40.65 kJ mol⁻¹
Heat of fusion (0 °C)6.008 kJ mol⁻¹
CO₂ (carbon dioxide)
Sublimation point (1 atm)194.65 K (−78.5 °C)
Triple point216.58 K, 0.5185 MPa
Critical point (Tc, Pc)304.13 K, 7.375 MPa
H₂S (hydrogen sulfide)
Melting / boiling point187.61 / 213.61 K
SO₂ (sulfur dioxide)
Melting / boiling point197.69 / 263.13 K
CH₄ (methane)
Melting / boiling point90.67 / 111.65 K
Critical point (Tc, Pc)190.56 K, 4.599 MPa
C₂H₄ (ethylene)
Melting / boiling point104.00 / 169.42 K
C₂H₆ (ethane)
Melting / boiling point90.35 / 184.57 K
C₃H₈ (propane)
Melting / boiling point85.47 / 231.04 K
CH₃OH (methanol)
Melting / boiling point175.61 / 337.85 K
C₂H₅OH (ethanol)
Melting / boiling point159.05 / 351.44 K
C₆H₆ (benzene)
Melting / boiling point278.68 / 353.22 K
Critical point (Tc, Pc)562.05 K, 4.895 MPa