1. O
96 pm
104.5o
H H
Fig. 1. A Model for the Water Molecule

2. Fig. 2. Molecules of CH4, NH3 and H2O
Lone pair electrons
• •
• •
• •
CH4
C–H, 110 pm H-C-H, 109.5o
NH3
H–N, 100 pm H-N-H, 107o
H2O
H–O, 96 pm H-O-H, 104.5o
Fig. 2. Molecules of CH4, NH3 and H2O

3. 1 2 3
Fig. 3. The three principle vibration modes of the water molecule, H2O: 1, symmetric stretching, 2, bending, and 3, asymmetric stretching.

4. Fig. 4. Infrared absorption spectrum of Gas-phase H2O plotted using NIST/EPA Gas-phase infrared database (webbok.nist.gov/chemistry)

5. H O H
H O
(a)
H H O O
H H
(b)
Fig. 5. Two possible structures of the water dimer, (H2O)2