1. Basic Chemistry- Chemical Bond Video

2. Chemical Equations
Chapter 10

3. Chemical Reactions Chemical reactions are chemical changes
A change that takes place at the atomic level (a new substance if formed)
Two ways:
Forming/making bonds
Break bonds
Both forms take energy

4. Parts of a Chemical Reaction
2 main parts
Reactants
Products

5. Reactants These undergo the changes
Can be one molecule or a bunch of single atoms
2H2 + O H2O
The reactants

6. Products This is the result of the chemical reaction
Can also be one molecule or a bunch of single atoms depending on the type of reaction that took place
2H2 + O H2O
The product

7. Chemical Equations
These chemical changes are represented by a chemical equation like you see below
It shows the atoms that go through the changes and the result of that change
2H2 + O H2O
The reactants
The products
Yields/produces
Coefficient shows how many of that molecule you have
The subscript shows how many of that particular atom you have

8. Chemical Equations Must be balanced!
Because of The law of Conservation of mass (matter can never be created nor destroyed.)
The total number of atoms for each element in the reactants must be EQUAL to the total number of atoms for element in the products
2H2 + O H2O

9. __ N2 +__ H2 ___ NH3 Balancing Equations
First thing you will need to do is count the atom for each element
Element
Reactant
Product N H

10. __ N2 +__ H2 ___ NH3 Balancing Equations
First thing you will need to do is count the atom for each element
Element
Reactant
Product N 2 1 H 3

11. __ N2 +__ H2 ___ NH3 Balancing Equations
Change the coefficients to make them equal (use some guess and check)
Element
Reactant
Product N 2 1 H 3

12. N2 + 3 H2 2 NH3 Balancing Equations
Check to make sure the atoms are the same on both sides of the arrow
Element
Reactant
Product N 2 H 6

13. Your turn Balance the equations on the board.

14. Types of Chemical Reactions
There are three main types of chemical reactions
Synthesis (combination)
Decomposition
Displacement (switching)

15. Synthesis or Combination
Separate reactions will combine or bond forming a new substance
A + B AB
A + BC ABC
Balance the following combinations:
S SO3
Mg O2 MgO
Na Cl NaCl

16. Decomposition
Bonds are separated, a large molecule is broken up in to smaller molecules or atoms
AB A+B
ABC A+ BC
Balance Equations
1. HgO Hg O2
2. H2O2 O H2O
3. H2CO3 H2O + CO2

17. Displacement (switching)
The reactants are switched to make different bonds/combinations in the product AB+ C A+ BC 1. NaBr + Cl2 NaCl + Br2 2. Al + CuO Al2O3 + Cu

18. Energy in Reactions Energy is needed for every reaction!
Depending on the way the energy is used, determines the type of reaction
In order to start any type of reaction you must have a certain amount of energy
Activation energy- minimum amount of energy required to start (activate) a reaction

19. Energy in Reactions
Endothermic- heat is absorbed by the reaction (energy is absorbed) because it requires more energy
Examples:
Photosynthesis
Evaporation/melting
Electrolysis

20. Energy in Reactions
Exothermic- heat is released by the reaction (energy is released)
Examples:
Combustion
Freezing
Flames
rusting

21. Reaction Rate
Chemical reactions take different amounts of time depending on the type of reaction
Catalyst- increases the rate of reaction by lowering the activation energy required
Enzyme- type of catalyst (biological)
Inhibitor- slows down reactions