 So understanding redox reactions are very important in chemistry. Redox reactions are reactions that involve reduction and oxidation And we'll talk about what those terms mean shortly Most reactions are redox reactions. So examples down here. We have Elmo combusting. So combustion reactions their redox reactions Here we have a battery running a very easy small motor All the chemistry involved in batteries are redox chemistry So it's redox reactions going on involved in now batteries that cause batteries to do what they do so chemistry is the domain of the Electron and redox reactions are about electron exchange. So who's giving an electron to who that's really the question Reduction oxidation go together. You never have one without the other because in one reaction You have an electron being given off and in the other other action you have the electron being taken in So that's reduction oxidation The electrons that are lost in an oxidation reaction So oxidation is lost they're gained in reduction reactions reductionist game So we're going to focus on those terms there and focus on what electrons are doing So let's have a look at what happens in an oxidation and a reduction reaction So we're going to start by looking at oxidation. Now, there's many different ways you can define what oxidation is We could say it's the gain of oxygen the loss of hydrogen the loss of electrons or an increase in oxidation number We're going to focus mainly on those last two in the unit that we're doing So a gain of oxygen losses hydrogen loss of electrons increase in oxidation number the way I remember this is oxidation is lost oil So it's loss of electrons because I'm focusing on the electrons. That's what I care most about So oxidation is loss of electrons Reduction is the opposite of oxidation So we can define as the loss of oxygen the gain of hydrogen the gain of electrons and a reduction in oxidation number And again, we're probably going to focus mainly on these ones down the bottom here The way that I remember this is Rick because I'm going to focus on the electrons. So reduction is gain of electrons So when a substance gains electrons in a chemical reaction, that is a reduction reaction It is being reduced. So oil rig. That's the way I remember it. There are other mnemonics You can use Leo says good, but oil rig. I think is the easiest one