1. REDOX Reactions
Oxidation – Reduction

2. Oxidation – Reduction Reaction
These reactions involve a transfer of electrons
Half reactions MUST occur simultaneously
Oxidation – loss of electrons
Oxidizing agent – a substance that has the potential to cause another substance to be oxidized

3. Oxidation – Reduction Reaction
Reduction – involves the gain of electrons
Reducing agent – a substance that has the potential to cause another substance to be reduced (gain electrons)

4. Oxidation States The oxidation number of a pure element is 0
The oxidation number of a monatomic ion equals the charge on the ion
The more electronegative element in a binary compound is assigned the number equal to the charge it would have it were an ion
The oxidation number of fluorine in a compound is always -1
Oxygen has an oxidation number of -2 unless it is combined with Fluorine, in which it is +1 or +2, or it is in a peroxide, in which it is -1

5. Oxidation States
Hydrogen’s oxidation state in most of its compound is +1, unless it is combined with a metal, in which case it is -1
In compounds, Group 1 and Group 2 elements and aluminum have oxidation numbers of +1, +2, and +3 respectively
The sum of the oxidation numbers of all atoms in a neutral compound in 0
The sum of the oxidation numbers of all atoms in a polyatomic ion equals the charge of the ion

6. Oxidation
Oxidation is the process in which atoms or ions of an element experience an increase in oxidation states
2 Na (s) + Cl2 (g) 2 NaCl(s)
Sodium undergoes an oxidation process because the sodium atoms loses an electron and become a sodium ion – sodium is an oxidized to a sodium ions
Electrons are on the right side of the arrow)
A species whose oxidation number increases is oxidized
0 +1
Na  Na+ + e-

7. Reduction
Reduction is the process in which the oxidation state of an element decreases
2 Na (s) + Cl2 (g) 2 NaCl(s)
 Each chlorine atom accepts an electrons and becomes a chloride ion
Electrons are on the left side of the arrow
Cl2 + 2e-  2Cl-
A species that undergoes a decrease in oxidation state is reduced

8. Oxidation – Reduction Reaction
Lose Gain
Electrons Electrons
Oxidation Reduction
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