1. Please have a seat. Write down the homework assignment and answer the following 2 questions.
Please pick up a copy of powerpoint notes.

2. KEY CONCEPT Life depends on chemical reactions.

3. The ability to do work or cause change Occurs in various forms
Energy and Matter
Energy
The ability to do work or cause change
Occurs in various forms
Can be converted to another form
Forms important to biological systems are chemical, thermal, electrical and mechanical energy
Free energy is the energy in a system that is available for work

4. States of Matter Atoms are in constant motion
The rate at which atoms or molecules in a substance move determines its state

5. Solid Molecules tightly linked together in a definite shape
Vibrate in place
Fixed volume and shape

6. Liquids Molecules not as tightly linked as a solid
Maintain fixed volume
Able to flow and conform to shape of container

7. Molecules have little or no attraction to each other
Gas
Molecules have little or no attraction to each other
Fill the volume of the occupied container
Move most rapidly
To cause a substance to change state, thermal energy (heat) must be added to or removed from a substance

8. Living things undergo thousands of chemical reactions as part of the life process

9. Many are very complex involving multistep sequences called biochemical pathways
Chemical equations represent chemical reactions
Reactants are shown on the left side of the equation
Products are shown on the right side

10. The number of each kind of atom must be the same on either side of the arrow (equation must be balanced)
Bonds may be broken or made forming new compounds
C6H12O6 + 6O CO2 + 6H2O

11. Bonds break and form during chemical reactions.
Chemical reactions change substances into different ones by breaking and forming chemical bonds.
Reactants are changed during a chemical reaction.
Products are made by a chemical reaction.
C6H12O6 + 6O CO2 + 6H2O
Products
Reactants

12. Bond energy is the amount of energy that breaks a bond.
Energy is added to break bonds.
Energy is released when bonds form.
A reaction is at equilibrium when reactants and products form at the same rate.
CO2 + H2O H2CO3

13. 1. How is bond formation represented by the snapping sound?
2. How is bond energy related to your separation of magnets?

14. Chemical reactions release or absorb energy.
Activation energy is the amount of energy that needs to be absorbed to start a chemical reaction.

15. Exothermic (also exergonic) reactions release more energy than they absorb (e.g. cellular respiration).
Reactants have higher bond energies than products.
Excess energy is released by the reaction.

16. Endothermic reactions (also endergonic) absorb more energy than they release (e.g. photosynthesis).
Reactants have lower bond energies than products.
Energy is absorbed by the reaction to make up the difference.

17. Oxidation reaction – reactant loses electron(s) becoming more positive
Reduction-Oxidation Reactions
Many of the chemical reactions that help transfer energy in living organisms involve the transfer of electrons (reduction-oxidation = redox reactions)
Oxidation reaction – reactant loses electron(s) becoming more positive
Reduction reaction – reactant gains electron(s) becoming more negative