2. Properties of Water The most important inorganic compound for living organisms!

3. Water is POLAR! Water has an unequal distribution of charges…the O atom has a (-) charge & each H atom has a (+) charge. Water has an unequal distribution of charges…the O atom has a (-) charge & each H atom has a (+) charge. Polarity refers to the property of having 2 opposite poles. Polarity refers to the property of having 2 opposite poles. HOW DOES THIS RELATE?

4. Hydrogen Bonds The oppositely charged ends of a water molecule can form weak interactions with each other known as HYDROGEN BONDS! The oppositely charged ends of a water molecule can form weak interactions with each other known as HYDROGEN BONDS! Opposites Attract!

5. Cohesive An attraction of molecules of the same substance An attraction of molecules of the same substance Water can “stick” to itself….surface tension! Water can “stick” to itself….surface tension! Explains why some insects can “walk on water” Explains why some insects can “walk on water”

6. Adhesive An attraction between molecules of different substances. An attraction between molecules of different substances. Allows for capillary action….draws water out of roots up into the stems. Allows for capillary action….draws water out of roots up into the stems.

7. Water has a high heat capacity…what does that mean? Water is able to absorb large amounts of heat. Water is able to absorb large amounts of heat. As a result, lakes and oceans stabilize air and land temperatures. As a result, lakes and oceans stabilize air and land temperatures.

8. Ice floats? Yes, Water is more dense as a liquid than a solid! Yes, Water is more dense as a liquid than a solid! Prevents lakes & ponds from freezing solid…life can survive at the bottom Prevents lakes & ponds from freezing solid…life can survive at the bottom Also allows for mixing of nutrients in water Also allows for mixing of nutrients in water

9. Universal Solvent Most all of our chemical reactions take place in SOLUTIONS….comprised of a solute (the substance dissolved) and a solvent (the substance in which the solute dissolves)…water is the greatest solvent on Earth! Most all of our chemical reactions take place in SOLUTIONS….comprised of a solute (the substance dissolved) and a solvent (the substance in which the solute dissolves)…water is the greatest solvent on Earth!

10. In summation, Water is essential for life on Earth! Water is essential for life on Earth!

11. pH and the Importance to Life

12. Acids Bases Acids Bases Produces H + ions in solution and have pH values less than 7 Produces H + ions in solution and have pH values less than 7 Produces OH - ions in solution and have ph values greater than 7 H 2 O  H + + OH - Waterhydrogenhydroxide *Pure water is NEUTRAL and has a pH of 7.

13. pH Scale: NOTE: Every # is a factor of 10X ! 0 Acid 7 Base 14 Stronger Neutral Stronger

14. Why do we care in BIOLOGY? Stomach is acidic (help break down food) Stomach is acidic (help break down food) Soil pH is key to plant life (Hydrangeas change color based on pH of soil) Soil pH is key to plant life (Hydrangeas change color based on pH of soil) Acid Precipitation (affects both aquatic life and plants) Acid Precipitation (affects both aquatic life and plants) Most biological processes take place in pH close to NEUTRAL (6.5-7.5), some slightly basic or acidic Most biological processes take place in pH close to NEUTRAL (6.5-7.5), some slightly basic or acidic Enzymes function at certain pH Enzymes function at certain pH

15. What is a buffer? Mixtures that can react with acids or bases to keep the pH within a certain range Mixtures that can react with acids or bases to keep the pH within a certain range Example – buffers in blood to keep pH about 7.4 Example – buffers in blood to keep pH about 7.4

16. Let’s Watch!! http://www.youtube.com/watch?v=zTLi JE-j1- I&feature=PlayList&p=37CBB4FE24FC3 885&playnext=1&playnext_from=PL&in dex=42 http://www.youtube.com/watch?v=zTLi JE-j1- I&feature=PlayList&p=37CBB4FE24FC3 885&playnext=1&playnext_from=PL&in dex=42 http://www.youtube.com/watch?v=zTLi JE-j1- I&feature=PlayList&p=37CBB4FE24FC3 885&playnext=1&playnext_from=PL&in dex=42 http://www.youtube.com/watch?v=zTLi JE-j1- I&feature=PlayList&p=37CBB4FE24FC3 885&playnext=1&playnext_from=PL&in dex=42