## Acetaldehyde, CH3CH=O

 H3 H6 \ / H5 - C1 - C2 / \\ H4 O7
Tell me about the atomic charges, dipole moment, bond lengths, angles, bond orders,
molecular orbital energies, or total energy.
Tell me about the best Lewis structure.

## Atomic Charges and Dipole Moment

C1 charge=-0.420
C2 charge= 0.532
H3 charge= 0.125
H4 charge= 0.145
H5 charge= 0.119
H6 charge=-0.025
O7 charge=-0.477
with a dipole moment of 3.03216 Debye

## Bond Lengths:

between C1 and C2: distance=1.509 ang___ between C1 and H3: distance=1.107 ang___
between C1 and H4: distance=1.101 ang___ between C1 and H5: distance=1.106 ang___
between C2 and H4: distance=2.167 ang___ between C2 and H6: distance=1.124 ang___
between C2 and O7: distance=1.225 ang___

## Bond Angles:

for H3-C1-C2: angle=108.8 deg___ for H4-C1-C2: angle=111.2 deg___
for H5-C1-C2: angle=109.9 deg___ for H6-C2-C1: angle=115.3 deg___
for O7-C2-C1: angle=124.5 deg___

## Bond Orders (Mulliken):

between C1 and C2: order=0.817___ between C1 and H3: order=0.957___
between C1 and H4: order=0.994___ between C1 and H5: order=0.965___
between C2 and H4: order=-0.056___ between C2 and H6: order=0.953___
between C2 and O7: order=1.869___

## Best Lewis Structure

The Lewis structure that is closest to your structure is determined. The hybridization of the atoms in this idealized Lewis structure is given in the table below.

### Hybridization in the Best Lewis Structure

1. A bonding orbital for C1-C2 with 1.9955 electrons
__has 51.72% C 1 character in a sp2.65 hybrid
__has 48.28% C 2 character in a sp1.72 hybrid

2. A bonding orbital for C1-H3 with 1.9782 electrons
__has 60.25% C 1 character in a s0.91 p3 hybrid
__has 39.75% H 3 character in a s orbital

3. A bonding orbital for C1-H4 with 1.9930 electrons
__has 60.90% C 1 character in a sp2.88 hybrid
__has 39.10% H 4 character in a s orbital

4. A bonding orbital for C1-H5 with 1.9818 electrons
__has 60.11% C 1 character in a s0.93 p3 hybrid
__has 39.89% H 5 character in a s orbital

5. A bonding orbital for C2-H6 with 1.9889 electrons
__has 56.24% C 2 character in a sp2.34 hybrid
__has 43.76% H 6 character in a s orbital

6. A bonding orbital for C2-O7 with 1.9984 electrons
__has 34.99% C 2 character in a sp1.94 hybrid
__has 65.01% O 7 character in a sp1.47 hybrid

7. A bonding orbital for C2-O7 with 1.9936 electrons
__has 30.53% C 2 character in a p-pi orbital ( 99.42% p 0.58% d)
__has 69.47% O 7 character in a p-pi orbital ( 99.81% p 0.18% d)

11. A lone pair orbital for O7 with 1.9832 electrons

12. A lone pair orbital for O7 with 1.9100 electrons

-With core pairs on: C 1 C 2 O 7 -

#### Donor Acceptor Interactions in the Best Lewis Structure

The localized orbitals in your best Lewis structure can interact strongly. A filled bonding or lone pair orbital can act as a donor and an empty or filled bonding, antibonding, or lone pair orbital can act as an acceptor. These interactions can strengthen and weaken bonds. For example, a lone pair donor->antibonding acceptor orbital interaction will weaken the bond associated with the antibonding orbital. Conversly, an interaction with a bonding pair as the acceptor will strengthen the bond. Strong electron delocalization in your best Lewis structure will also show up as donor-acceptor interactions.
Interactions greater than 20 kJ/mol for bonding and lone pair orbitals are listed below.

The interaction of bonding donor orbital, 2, for C1-H3 with the second antibonding acceptor orbital, 96, for C2-O7 is 30.7 kJ/mol.

The interaction of bonding donor orbital, 4, for C1-H5 with the second antibonding acceptor orbital, 96, for C2-O7 is 22.9 kJ/mol.

The interaction of the second lone pair donor orbital, 12, for O7 with the antibonding acceptor orbital, 90, for C1-C2 is 98.6 kJ/mol.

The interaction of the second lone pair donor orbital, 12, for O7 with the antibonding acceptor orbital, 94, for C2-H6 is 124. kJ/mol.

## Molecular Orbital Energies

The orbital energies are given in eV, where 1 eV=96.49 kJ/mol. Orbitals with very low energy are core 1s orbitals. More antibonding orbitals than you might expect are sometimes listed, because d orbitals are always included for heavy atoms and p orbitals are included for H atoms. Up spins are shown with a ^ and down spins are shown as v.

16 ----- 2.605

15 ----- 1.935

14 ----- 1.649

13 ----- -2.272

12 -^-v- -5.982

11 -^-v- -9.117

10 -^-v- -9.715

9 -^-v- -10.67

8 -^-v- -11.07

7 -^-v- -11.76

6 -^-v- -14.23

5 -^-v- -18.64

4 -^-v- -26.01

3 -^-v- -266.7

2 -^-v- -268.9

1 -^-v- -506.5

## Total Electronic Energy

The total electronic energy is a very large number, so by convention the units are given in atomic units, that is Hartrees (H). One Hartree is 2625.5 kJ/mol. The energy reference is for totally dissociated atoms. In other words, the reference state is a gas consisting of nuclei and electrons all at infinite distance from each other. The electronic energy includes all electric interactions and the kinetic energy of the electrons. This energy does not include translation, rotation, or vibration of the the molecule.

Total electronic energy = -153.8860360491 Hartrees