1. Energy and Reactions
Honors Biology

2. Energy Energy – ability to do work or cause a change
Kinetic Energy  energy of motion
Ex: Heat, moving ball
Potential Energy  stored energy as a result of position or location
Ex: Sitting ball
ATP – adenosine triphosphate
Unit of energy cells use
3 phosphates; 3rd P has high energy bond

3. ATP
Adenine
Triphosphate
Ribose

4. Chemical Reactions
Bonds between atoms are made or broken and the substances change into something else
Represented by chemical equations
Ex: Methane burning in air
CH4 + 2O2 → CO2 + 2H2O
(reactants) (products)
Equation must be balanced (coefficient vs. subscript)… PRACTICE!!!
Atoms are never created or destroyed, only change form

5. PRACTICE PROBLEMS
1) ____ H2 + ____ O2  ____ H2O 2) __ AlBr3 + __ Cl2  __ AlCl3 + Br2 **3) __Ca(OH)2 + __H3PO4  __ Ca3(PO4)2 + __H2O

6. Answers WRONG: 4AlBr3 + 6 Cl2  4 AlCl3 + 6 Br2

7. Answers 1) 2 H2 + 1 O2  2 H2O 2) 2 AlBr3 + 3 Cl2  2 AlCl3 + 3 Br2
**3) 3 Ca(OH)2 + 2 H3PO4  1 Ca3(PO4)2 + 6 H2O

8. Endergonic Reactions – absorbs energy
Energy absorbed from surroundings and stored in bonds
Ex: Photosynthesis
Products have more ENERGY than reactants
Exergonic Reactions – releases energy
Releases ENERGY to environment
Ex: Cellular Respiration
Reactants have more ENERGY than products
Energy Coupling – Energy released from exergonic rxns powers endergonic ones

9. Real Life Examples… Exergonic (Exothermic) Cellular Respiration
Energy (ATP) is released when glucose is broken down
Endergonic (Endothermic)
Photosynthesis
Energy (ATP) is NEEDED (consumed) to put together glucose from CO2, H20 and sunlight