I understand the concept of oxidation states and how to find them, but what confuses me is how an atom "decides" which oxidation state to choose. Or even "what it is at all" that decides the oxidation state. Specifically, the transition metals with multiple oxidation states seem to be the tougher ones. An example of this "decision" I found was in my Holt, Rinehart, and Winston Modern Chemistry textbook for my chem class. When talking about different synthesis reactions between Iron and Oxygen to form Iron Oxide, it states; "In the product of the first reaction, iron is in an oxidation state of +2. In the product of the second reaction, iron is in an oxidation state of +3. The particular oxide formed depends on the conditions surrounding the reactants." The specific part of that is the "conditions surrounding the reactants" part. What are these conditions that determine oxidation state? When I asked my teacher, she said that temperature could possibly be one, but wasn't certain. Any insight is much appreciated!