1. Types of Reactions

2. Classifying Reactions
How can you predict the products if you are given the reactants?
Must know the types of reactions

3. Types of Reactions Addition (Synthesis) Decomposition
Single Displacement (Replacement)
Double Displacement (Replacement)
Combustion
Acid Base

4. Addition (Synthesis)
Two or more reactants combine to form a new product
A + B  AB
Example: Rust formation:
Fe(s) + O2(g)  Fe2O3

5. Decomposition
Compounds are broken down into two or more smaller compounds
AB  A + B
SiCl4  Si + Cl2

6. Single Displacement One element replaces another in a compound
AX + B  BX + A
Ca + HCl  CaCl2 + H2

7. Double Displacement Ions switch places; two elements switch places
AB + CD  AD + CB
AgNO3 + NaCl 
AgCl + NaNO3

8. Combustion
Carbon compound combines with oxygen to release carbon dioxide and water and energy
Carbon cmpd + O2 
CO H energy!
C2H6 + O2  CO2 + H20

9. Acid Base Reactions
The reactants will always be an acid and a base producing 2 specific products; Water and a Salt.
Acids always start with an H-
Bases always end in an –OH
Water is H20
HCl + NaOH  H20 + NaCl

10. Let’s practice- Type _______ HgO → Hg + O2
_______ CH4 + O2 → CO2 + H2O
_______ NaCl + AgNO3 → NaNO3 + AgCl
_______ Mg + HCl → MgCl2 + H2
_______ Zn + H2SO4 → ZnSO4 + H2
_______ C6H12O6 + O2→ CO2 + H2O
_______ NaOH + HCl → NaCl + H2O
_______ Al2(SO4)3 + Ca(OH)2 → Al(OH)3 + CaSO4
_______ H2 + O2 → H2O
_______ Cl2 + NaBr → NaCl + Br2
_______ KClO3 → KCl + O2
_______ C2H2 + O2→ CO2 + H2O
_______ Na2O + CO2 → Na2CO3

11. Categorizing Chemical Reactions
All chemical reactions involve something moving, so we can categorize the types of reactions we just learned to help us predict the products in a reaction!
Moving electrons = synthesis, decomposition, single displacement, combustion.
Moving ions = double displacement
Moving protons = acid/base reaction (we’ll get into this in a later unit)

12. Moving Electrons
In the following reactions, one or more electrons move from one atom to another
This allows the atoms to act differently than in their original compounds, and we form new substances.
Ex:
Mg + Br2  MgBr2
NaCl  Na + Cl2
Zn + CuSO4  Cu + ZnSO4

13. In the first example, think about the Lewis Structures that we’ve drawn.
The Magnesium atom loses electrons and the Bromine atom gains electrons.
There is a transfer of electrons to create the ionic bond.

14. In the second example, we break apart the compound by transferring the electrons back to the individual elements.

15. Zn + CuSO4  Cu + ZnSO4
Remember CuSO4 is an ionic compound, so it really is made of Cu+2 and SO4-2 ions.
Zn is starting off neutral in the reactants.
During this reaction, Zn transfers its electrons to Cu+2 ion.
Zinc loses electrons and becomes a Zn+2 ion and Cu gains electrons to become neutral.
Now that Zn+2 has a charge, it will form the ionic compound with SO4-2 because the opposite charges ions will attract.

16. In this case, did the sulfate ion see an change of electrons?
No, so these electrons were not involved in the reaction and were not shown.
This is an example of something called a “Spectator Ion” and we’ll talk about it later.

17. Reduction and Oxidation
In these reactions, one atom or element is reduced and the other is oxidized. So you’ll hear these called Redox.
A substance that is reduced has gained electrons and the charge is reduced. (more negative)
A substance that is oxidized has lost electrons and the charge is increased. (more positive)

18. 2 Fun Ways to Remember Oxidation Is Losing elections Reduction
OIL RIG
LEO the lion says GER
Oxidation Is
Losing elections
Reduction
Gaining electrons
Losing
Electrons is
Oxidation
Gaining
Reduction

19. And now, the tricky part…
A substance that has been oxidized is called a reducing AGENT because it caused another element to take their electrons.
A substance that has been reduced is called an oxidizing AGENT because it caused another element to give up its own electrons

20. Br starts with 0 charge and ends with -1
The charge has gone down, because Br has gained electrons.
Mg starts with 0 charge and ends with +2
The charge has gone up, because Mg has lost electrons.
This means Br has been ______ and is the _______ agent.
reduced oxidizing
This means Mg has been ______ and is the _______ agent.
oxidized reducing

21. Na starts with a +1 charge, ends with 0 charge
Charge has gone down because it gained electrons
Cl starts with a -1 charge, ends with 0 charge
Charge has gone up because it lost electrons
This means Na has been _______ and is the ______ agent.
reduced oxidizing
This means Cl has been ______ and is the _______ agent.
oxidized reducing

22. Zn started with 0 charge, ended with +2
Charge has gone up because it lost electrons
Cu started with +2 charge, ended with 0
Charge has gone down because it gained electrons
SO4 started and ended with -2, no electrons changed here
Zn has been oxidized and is the reducing agent
Cu has been reduced and is the oxidizing agent
SO4 wasn’t really involved in the reaction. (Spectator)