We'll learn how to determine the oxidation numbers or oxidation states for a the elements in a chemical compound. The oxidation numbers tell us how electrons are divided up or shared between atoms in a chemical compound. The oxidation numbers also tell us how electrons move in an oxidation reduction (redox) reaction. There are a set a rules that we use to determine oxidation number. Group 1A elements (alkalai metals) always have an oxidation of +1. Group 2A elements (alkaline earth metals) always have an oxidation number of +2. Elements on their own have an oxidation number of 0, and monatomic ions have an oxidation number that is equal to the ionic charge.
We'll learn about oxidizing agents and reducing agents, what they are, what they do, and how to identify them in chemical equations. Oxidizing agents make oxidation happen, and reducing agents make oxidation happen. And oxidizing agent takes electrons from something, allowing it to be oxidized, and a reducing agents gives electrons to something, allowing it to be reduced. You can remember this by noting that the thing that is reduced is the oxidizing agent, and the thing that is oxidized is the reducing agent. We'll then look at some equations and identify the oxidizing and reducing agents. To do this, we have to write oxidation numbers (or oxidation states) for the elements in the equation, and then figure out how electrons are moving, what is being oxidized and what is being reduced.