In today's video, we're going to take a look at the reactivity series of metals and see how metals react with both acids and water. Then to finish, we'll take a quick look at how we use the reactivity series to figure out what will happen in displacement reactions. If you remember the electron arrangement of metals, what they all have in common is that they have electrons in their outermost shell that they want to get rid of. And so when they react with other substances, they get rid of these outer shell electrons and form positive ions. So when we talk about the reactivity of a metal, all we mean is how easily it forms these positive ions. The metals that form ions most easily are the most reactive. And by comparing all of the metals, we can arrange them in order of their reactivity like this, which we call the reactivity series. Now, even though carbon and hydrogen aren't metals, we often still include them in reactivity series as references to compare the metals against. The most reactive metals are the group one metals with the group two metals being a bit less reactive and the transition metals generally the least reactive. To figure out this list in the first place though, we need to react each of the metals with either acid or water and compare their relative reactivity by seeing how fast or violent the reactions are. If we react a metal with an acid, it will form a salt and hydrogen gas. For example, if we reacted potassium with hydrochloric acid, it would form potassium chloride and hydrogen. And because potassium is so reactive, it would react explosively, possibly catching fire and whizzing around as it produces loads of hydrogen. The reactions would then get gradually less violent as we go down the series. And by the time we get to magnesium, it would just produce lots of bubbles as the solid metal disappears in the acid. We'd then see fewer bubbles with zinc and iron. And copper usually won't react at all. Rather than just watching the reactions to see how violent they are, we can also measure the temperature change of the reactions. because the most reactive metals will produce the most heat. If we're going to compare the metals though, we need to make sure it's a fair test by ensuring that each of the metal samples that we use has the same mass and same surface area and that we use the same type and concentration of acid each time. Now if we instead react metals with water rather than acids, they form metal hydroxides and hydrogen. For example, lithium plus water would go to form lithium hydroxide and hydrogen. However, only the most reactive metals are reactive enough to do this. Zinc, iron, and copper won't react at all, while magnesium will only react very slightly. Now the last thing we need to cover is displacement reactions. The idea here is that more reactive metals can displace less reactive ones. So if we put some magnesium into a solution of iron sulfate, then the magnesium would displace the iron to form magnesium sulfate plus iron because the magnesium is more reactive than the iron. Whereas if we added copper to a solution of iron sulfate, then nothing would happen because copper is less reactive than iron, so can't displace it. If you haven't heard yet, you can find all of our videos on our website, cognito.org. You'll also find questions, flashcards, exam style questions, and pass papers. And we track all of your progress so that you always know what to study next. So sign up for free by clicking here or browse our playlist here on YouTube.