1. Chemistry of Life
What are some of the basic physical and chemical processes that allow energy to be stored and utilized by living things?

2. Chemistry of Life Atom – composed of Nucleus
Proton – positive charge
Neutron – neutral charge
Electrons – orbiting nucleus, negative charge

4. Chemistry of Life
Element – a substance consisting entirely of one type of atom.
Molecule – two or more atoms joined together by a chemical bond.
Chemical compounds – two or more elements joined together (can be the same or different type of element)

5. Types of Chemical Bonds
Chemical bonds – how atoms are held together. Energy is stored in the bonds!
Types of Chemical Bonds
Ionic bonds: electrons are transferred
one atom (or compound) loses electron; becomes positive
one atom (or compound) gains electron; becomes negative

6. Salt: NaCl  Na Cl-
Example of Ionic Bond

7. Covalent bonds: electrons are shared between atoms to form molecules
(not as strong as ion bonds! )
Water: H2O Each hydrogen atom bonds with the Oxygen atom

8. Hydrogen Bonding
Special type of bonding / attraction between water molecules.
It is the reason water will “beads up” (cohesion) or climbs up sides of graduated cylinder (adhesion) to form the meniscus.

9. Chemical Bonds
Van der Waals Forces - not as strong as ionic or covalent but are responsible for the Gecko’s ability to climb up a glass window

10. ACIDS, BASES, BUFFERS
pH – measurement the concentration of the H+ (hydrogen ions) in solution.
pH equal to 7: The Solution is Neutral

11. ACIDS, BASES, BUFFERS Acids: pH is less than 7
Release hydrogen ions H+ in solution
Has positive charge,
Juices, vinegar
Taste sour

12. ACIDS, BASES, BUFFERS Base pH greater than 7
Releases hydroxide ions OH- in solution
Ex. are ammonia, some soaps, lye
Taste bitter, feel slimey
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13. pH Scale

14. Buffers
Buffers: solutions that react with acids or bases and prevent sudden changes in pH, for example bicarbonate of soda, Tums