Download Section 7.1 Summary Notes

7.1 Oxidation-Reduction
•
Electrochemistry
•
Oxidation Numbers:
A System for Tracking Electrons
•
Oxidation and Reduction
•
Agents Cause Electron Transfer
7.1 Oxidation-Reduction
Electrochemistry
Electrochemistry is the study of the interconversion
of chemical and electrical energy.
Reactions that involve electron transfer are called
oxidation-reduction reactions or redox reactions for short.
7.1 Oxidation-Reduction
Oxidation Numbers:
A System for Tracking Electrons
The oxidation number is the real or apparent charge of an
atom or ion when all bonds in the species containing the
atom or ion are considered to be ionic.
7.1 Oxidation-Reduction
Oxidation Numbers:
A System for Tracking Electrons
Rules for Assigning Oxidation Numbers:
1.
2.
3.
4.
Atoms in the elemental form = 0
Monatomic ions = the ion’s charge
Oxygen = −2 (except in peroxides = −1 and OF2 = +1)
Hydrogen = +1 (except in metal hydrides = −1)
7.1 Oxidation-Reduction
Oxidation Numbers:
A System for Tracking Electrons
Rules for Assigning Oxidation Numbers (Continued):
5. Oxidation numbers in compounds must sum to zero.
6. Oxidation numbers in polyatomic ions must sum to the ion charge.
7. Always assign the more electronegative element a negative
oxidation number.
8. In a compound or ion containing more than 2 elements, the
element written furthest to the right takes its most common
oxidation number.
7.1 Oxidation-Reduction
Oxidation and Reduction
LEO says GER
Losing Electrons is Oxidation.
Gaining Electrons is Reduction.
A decrease in oxidation number is reduction.
An increase in oxidation number is oxidation.
7.1 Oxidation-Reduction
Agents Cause Electron Transfer
A species that is reduced acts as an oxidizing agent.
In other words, oxidizing agents get reduced.
A species that is oxidized acts as a reducing agent.
In other words, reducing agents get oxidized.