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1. Two water molecules involved in a hydrogen bond:
Remember to draw your hydrogen bond as a dashed line and NOT a solid line (solid lines are reserved for covalent bonds).
2. When a water molecule forms a hydrogen bond with another water molecule, this is called cohesion; when a water molecule hydrogen bonds to another substance, it is called adhesion.
3. Water becomes less dense when it freezes (which is why your ice floats on the surface of your drink).
4. Water resists quick changes in temperature and doesn’t easily evaporate (or freeze); this is due to water’s high heat capacity.
5. It is only a partial charge (either negative or positive) because electrons are not evenly distributed throughout the molecule. If you said a full positive or negative charge, you would mean a complete loss (or gain) of an electron, which would make a water molecule an ion (which it’s not!).
6. The polarity of a water molecule (as described in the previous question) allows the partially positive side of one molecule to attract the partially negative side of another molecule. It’s like two magnets sticking to one another.
7. Cohesion creates surface tension because the water molecules are holding on to one another.
8. The ice floating on the surface acts as insulation to the water below, keeping it warmer. Furthermore, if ice sank, entire bodies of water would freeze solid in the winter, killing all life within it.
9. When water melts or boils, the hydrogen bonds between individual water molecules are being broken apart. The covalent bonds within individual water molecules do NOT break; otherwise, when you boil water, you would be producing oxygen and hydrogen gases (you’re not!).