Properties of Water and pH Chapter 3 Section 3.1

WATER 1. Covers more than 70% of Earth’s surface 2. Major reason there is life on our planet 3. Unique compound with several unusual properties

Properties of Water 1. Polar molecule - a partial negative charge at the oxygen and partial positive charge at the two hydrogen ends a) This creates a special type of attraction called a “hydrogen bond”. b) The positive end of a water molecule is attracted to the negative end of another water molecule

a) Water sticks to itself b) Allows the transport of material inside of cells c) Such a powerful attraction that certain insects can “walk on water” d) Adhesion- water molecules “stick to” or adhere to other substances (ex. Glass window) 2. Cohesion

3. Resistance to Temperature Change a) Water can absorb a large amount of energy with only small changes in its temperature. b) Stabilizes aquatic ecosystems c) Helps stabilize the climate d) This is why coastal areas are cooler in the summer and warmer in the winter.

4. Ice density a) In ice, water molecules are farther apart than in liquid water so ice is less dense than liquid water b) Reason why ice floats

5. Universal Solvent a) Water molecules will bond with other polar molecules b) As a result, water will dissolve with many other molecules

Acids, Bases, and pH 1. When a water molecule is separated, it separates into ions 2. Ions are slightly charged particles 3. Water---- Hydrogen Ion (H+) and Hydroxide Ion (OH)- 4. Acid= lots of hydrogen ions 5. Base= lots of hydroxide ions

6. pH scale runs from 0 to = perfectly neutral 8. Pure water= 7 9. Tap water has ions in it (chlorine kills germs and flourine is good for our teeth)