Aim How do chemists write halfreactions Each atom

Aim: How do chemists write “halfreactions”? • Each atom has a nucleus, with an overall positive charge, surrounded by negatively charged electrons. • Each electron in an atom has its own distinct amount of energy. • An oxidation-reduction (redox) reaction involves the transfer of electrons (e-).

Aim: How do chemists analyze reduction-oxidation reactions? • Reduction is the gain of electrons. • A half-reaction can be written to represent reduction. • Oxidation is the loss of electrons. • A half-reaction can be written to represent oxidation. • Oxidation numbers (states) can be assigned to atoms and ions. Changes in oxidation numbers indicate that oxidation and reduction have occurred.

Aim: How do chemists analyze reduction-oxidation reactions? • In all chemical reactions there is a conservation of mass, energy, and charge. • In a redox reaction the number of electrons lost is equal to the number of electrons gained.

Aim: How do chemists analyze reduction-oxidation reactions? Essential Questions: • Why is it only electrons that are transferred in chemical reactions? • How does one assign oxidation numbers? • How do chemists determine which elements are oxidized and which ones are reduced in in “redox” reaction?

Aim: How do chemists analyze reduction-oxidation reactions? Essential Questions: • Draw an electron dot diagram depicting a redox reaction. • Why does reduction and oxidation always occur simultaneously? • The Golden Gate Bridge (iron and steel) needs constant repainting. Explain using concept of oxidation-reduction reactions. • Use scientific evidence to support your argument that the Statue of Liberty is NOT painted green.