1. Oxidation and Reduction
Definitions of oxidation and reduction
Oxidation numbers
Redox equations

2. Oxidation - reduction Oxidation is loss of electrons (OIL)
Reduction is gain of electrons (RIG)
Oxidation is always accompanied by reduction
This is called a redox reaction.
An electron transfer reaction.
The total number of electrons lost equals the total gained.

3. Oxidation - reduction
Oxidizing agents oxidize and are themselves reduced
Reducing agents reduce and are themselves oxidized

4. Follow the electrons

5. Oxidation numbers
Oxidation number is the number of electrons gained or lost by the element in making a compound
Metals are typically considered more 'cation-like' and would possess positive oxidation numbers, while
nonmetals are considered more 'anion-like' and would possess negative oxidation numbers.

6. Predicting oxidation numbers
Oxidation number of atoms in element is zero in all cases
Oxidation number of element in monatomic ion is equal to the charge.
Sum of the oxidation numbers in a compound is zero
Sum of oxidation numbers in polyatomic ion is equal to the charge
F has oxidation number –1
H has oxidn no. +1; except in metal hydrides where it is –1
Oxygen is usually –2. Except:
O is –1 in hydrogen peroxide, and other peroxides
O is –1/2 in superoxides KO2
In OF2 O is +2

7. Position of element in periodic table determines oxidation number
GROUP 1A is +1
GROUP 2A is +2
GROUP 3A is +3 (some rare exceptions)
GROUP 5A are –3 in compounds with metals, H or with NH4+.
GROUP 6A below O are –2 in binary compounds with metals, H or NH4+.
GROUP 7A elements are –1 in binary compounds with metals, H or NH4+ or with a heavier halogen.

8. Identifying reagents
Those elements that tend to give up electrons (metals) are typically categorized as reducing agents
Those that tend to accept electrons (nonmetals) are referred to as oxidizing agents.

9. Iron can reduce Cu2+ to Cu
The iron nail reduces the Cu2+ ions and becomes coated with metallic Cu. At the same time, the intensity of the blue color diminishes due to loss of Cu2+ ions from solution.

10. More active metals are strongly reducing

11. Any element can be both an oxidizer and reducer depending on relative positions in the activity series
Fe reduced Cu2+, but Cu can reduce Ag+ (lower activity
Fe2+ is reduced by Zn

12. Predicting results of displacement reactions
In this reaction the element metal A displaces the ion metal B from its compound
This will only occur if A lies above B in the activity series
Displacement reaction exercises

13. Nuggets of redox processes
Where there is oxidation there is always reduction
Oxidizing agent
Reducing agent
Is itself reduced
Is itself oxidized
Gains electrons
Loses electrons
Causes oxidation
Causes reduction

14. Identify redox by change in oxidation numbers: follow the flow of electrons
Reducing agent increases its oxidation number
Oxidizing agent decreases its oxidation number