1. The Nature Of Water By Mary Dann

2. Physical Properties of Water Water is necessary for life and is the most abundant component of living things Most marine organisms are between 70% and 80% water by mass Excellent solvent High boiling and freezing point

3. Water molecules are composed of two atoms of hydrogen and one atom of oxygen Oxygen carries a slight negative electrical Hydrogen atom carries a slight positive electrical charge Water molecule is polar: positive and negative end

4. Because water molecules are polar, they have a tendency to form hydrogen bonds The high boiling point of water (100⁰C) reflects the amount of energy needed to overcome the attractive forces of the hydrogen bonds When water freezes the molecules move away from each other Solid water (ice) is less dense then liquid water This allows oceans not to freeze completely and for marine life to continue

5. The polar nature of water molecules also accounts for water’s solvent properties Salt is a polar substance that dissolves easily in water Ions are individually charged particles Water is not able to dissolve molecules that are nonpolar like oils and petroleum products

6. Hydrogen bonds cause water molecules to be very cohesive Water has a high surface tension Contributes to the high boiling point of water Many small organisms like water strides have adapted to using surface tension so that they can live on the surface of the water

7. Water is attracted to the surface of objects that carry electrical charges.. This is called adhesion Water can rise in narrow spaces which is called capillary action

8. The amount of heat energy required to change the temperature of 1 gram of a substance 1 degree C is called specific heat or thermal capacity Large bodies of water maintain a constant temperature because of the large amount of heat it takes to change the temperature.

9. Chemical Properties of Water Compounds are classified as acids or bases based on how they iodize when put into water Acids form hydrogen ions Bases form hydroxide ions pH scale is an indicator of the number of hydrogen ions in a volume of a solution Ranges from 0-14

10. Water The End