AP Biology / Unit 1: Chemistry of Life
1.1 Structure of Water and Hydrogen Bonding
Notes
Water is polar: oxygen pulls electrons and is slightly negative; the hydrogens are slightly positive. Neighboring molecules form hydrogen bonds.
- Cohesion: water sticks to water (surface tension).
- Adhesion: water sticks to other surfaces (capillary action in xylem).
- High specific heat: stabilizes temperature.
- Ice is less dense than liquid water, so it floats.
Practice
Hydrogen bonds between water molecules form between:
Opposite partial charges attract.
Water climbing up thin xylem tubes is mainly due to:
Water sticks to itself and to the tube walls.
Coastal areas have milder temperatures because water:
Water absorbs and releases lots of heat with little temperature change.
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