1. Electrochemistry

2. Oxidation Loss of electrons to become more positive
Tends to occur to metals
2Mg(s) + O2(g)  2MgO(s)
2Mg(s) + O2(g)  2Mg O2-
Does not have to be in the presence of oxygen
Mg(s) + Cl2(g)  MgCl2(s)
Mg(s) + Cl2(g)  Mg Cl-

3. Reduction Gain of electrons to become more negative
Tends to occur to nonmetals
Mg(s) + Cl2(g)  MgCl2(s)
Mg(s) + Cl2(g)  Mg Cl-
Oxidation-reduction reactions (redox reactions) involve the transfer of electrons

4. Loss of
Electrons
Oxidation
Gain of
Electrons
Reduction
the lion says

5. Oxidation
Is a
Loss
Reduction
Is a
Gain

6. Redox Half Reactions
Redox reactions can be separated into two half-reactions to represent the oxidation and reduction separately
Zn(s) + CuSO4(aq)  Cu(s) + ZnSO4(aq)
Zn(s) + Cu2+(aq) + SO42-(aq)  Cu(s) + Zn2+(aq) + SO42-(aq)
Oxidation:
Zn(s)  Zn2+(aq) + 2e-
Reduction:
Cu2+(aq) + 2e-  Cu(s)

7. Practice
Worksheet: Writing REDOX reactions
p. 656 #7-11