Aim: What are oxidation and reduction? Do Now: 1.Sketch the structure of an atom. Label the subatomic particles. 2.Describe the relative masses and charges of the subatomic particles.

Oxygen and Redox Original understanding of oxidation and reduction: The substance gaining oxygen is oxidized, while the substance losing oxygen is reduced. 2Fe 2 O 3 + 3C  4Fe + 3CO 2 Reduced oxidized

Oxygen and Redox

Reduction-Oxidation Reactions (REDOX) reactions that involve the TRANSFER OF ELECTRONS; both reduction and oxidation must happen SIMULTANEOUSLY! Reduction = GAIN OF ELECTRONS by an atom or ion; OXIDATION NUMBER goes DOWN/REDUCES Oxidation = LOSS OF ELECTRONS by an atom or ion; OXIDATION NUMBER goes UP/INCREASES

Reduction-Oxidation Reactions (REDOX) A way to remember  L E O the lion goes G E R Lose e- oxidation gain e- reduction

Reduction-Oxidation Reactions (REDOX) Oxidation and reduction happen because of the DESIRE for electrons in a chemical reaction. Species prefer to either LOSE or GAIN electrons in a chemical reaction. If one atom LOSES electrons, there must be another atom that will GAIN electrons (Conservation of Charge).

Redox Reactions That Form Ions Mg  Oxidation Loss of e- Reducing Agent Reduction Gain of e- Oxidizing Agent

Redox Reactions That Form Ions The substance that loses electrons is called the reducing agent. The substance that gains electrons is called the oxidizing agent.

Redox Reactions That Form Ions Example: ___ Al + ___ CuCl 2  ___ ___________ + ___ ______ Aluminum is above Cu on Table J so it will replace it! Notice how Al is all by itself (on left of arrow) with a zero charge and then bonded (on rightof arrow) where it takes on a charge

Questions 1.What happens to reducing agents in chemical reactions? a.Reducing agents gain protons b.Reducing agents gain electrons. c.Educing agents are oxidized. d.Reducing agents are reduced.

Questions 2. Given the reaction: 2Na + 2H 2 O  2Na + + 2OH - + H 2 Which substance is oxidized? a.H 2 b.H + c.Na d.Na +

Questions 3. In the reaction 2H 2 (g) + O 2 (g)  2H 2 O(g) The oxidizing agent is? a.H 2 b.O 2 c.H + d.O 2-

Corrosion Iron corrodes by being oxidized to ions of iron by oxygen (rust). 2Fe(s) + O 2 (g) +2H 2 O(l)  2Fe(OH) 2 (s) 4Fe(OH) 2 (s) + O 2 (g) +2H 2 O(l)  4Fe(OH) 3 (s)

Summary Reduced=gains e- = oxidizing agent Oxidized= loses e- = reducing agent