1. Oxidation-Reduction
Redox Reactions

2. In many chemical reactions electrons are transferred from one atom to another

3. Oxidation Loss of electrons Creates (+) ions 2Na + Cl2 → 2NaCl
Na is oxidized
It goes from Na to Na+

4. Reduction Gaining electrons Creates (-) ions 2Na + Cl2 → 2NaCl
Cl is reduced
It goes from Cl to Cl-

5. Remember
OIL RIG
Oxidation I Is
Loss
Reduction
Gain

6. Oxidation-Reduction Redox Must occur together
The electrons are moved from one atom to another

7. Assigning Oxidation Rules
Write the formula if none is provided
Assign oxidation numbers
Any free element is 0
A monatomic ion is the charge of the ion
F in a compound is always -1
The more electronegative atom gets its normal charge
GP 1= +1, GP 2= +2, Al = +3
Hydrogen is +1 unless with a metal, then it is -1
Oxygen is -2 unless: with F it is +2 and in peroxides is -1
Calculate the rest of the oxidation numbers so that:
The sum of oxidation numbers for molecules is 0
The sum of oxidation numbers for ions is the charge of the ion.

8. Examples
CH4
NaHCO3
NO3-
Cl2