3. Water Basics Polar: part of the molecule is slightly positive… other part slightly negative – Oxygen (-) – Hydrogen (+) Oxygen “hogs” hydrogen electrons & becomes negative Hydrogen Bond: Positive hydrogen attracted to negative oxygen - - - - + + + + + + + +

4. Water Basics Polar: part of the molecule is slightly positive… other part slightly negative – Oxygen (-) – Hydrogen (+) Oxygen “hogs” hydrogen electrons & becomes negative Hydrogen Bond: Positive hydrogen attracted to negative oxygen - - - - + + + + + + + +

5. Water Basics Polar: part of the molecule is slightly positive… other part slightly negative – Oxygen (-) – Hydrogen (+) Oxygen “hogs” hydrogen electrons & becomes negative Hydrogen Bond: Positive hydrogen attracted to negative oxygen - - - - + + + + + + + +

6. Water Basics Polar: part of the molecule is slightly positive… other part slightly negative – Oxygen (-) – Hydrogen (+) Oxygen “hogs” hydrogen electrons & becomes negative Hydrogen Bond: Positive hydrogen attracted to negative oxygen - - - - + + + + + + + +

7. Water Properties Energy (heat, chemicals, etc…) needed to break H bonds High specific heat: Resists temp changes – Helps to maintain a constant body temp Cohesion: polar water molecules attracted to other polar water molecules (see bug picture) Adhesion: polar water sticks to other molecules

8. Solutions Solution: mixture where 1 substance dissolves in another 2 parts to a solution 1) Solute: substance that dissolves in a solution Atoms, ions, molecules 2) Solvent: substance in which the solute is dissolved, present in greater amounts Usually water Ex: Human blood – Plasma (water) is the solvent – Carbs, proteins, sugars, etc… is the solute

9. pH Scale pH scale measures the amount of H+ ions Some molecules release H+ ion when dissolved H+ ions accumulate (acids) Some molecules release OH- ions when dissolved OH- ions accumulate (bases) pH balance vital to life – Ex: Proteins break apart when outside normal pH