[Music] hi and welcome back to frees science lessons. co.uk by the end of this video you should be able to use the reactions between metals and water and metals and acids to construct a reactivity series you should then be able to describe in terms of electrons what happens when metals react in the next video we're going to look at how we can use the reactivity series to explain the displacement of metals in a previous video we looked at how group one metals react with water and I'm showing you here the reaction of potassium with water as you can see this is an extremely vigorous reaction when potassium reacts with water we make The Alkali potassium hydroxide and the gas hydrogen here's sodium reacting with water as you can see sodium reacts less rapidly with water than potassium when sodium reacts with water it produces The Alkali sodium hydroxide and hydrogen gas finally here's lithium reacting with water lithium reacts more slowly than either potassium or sodium when lithium reacts with water it produces The Alkali lithium hydroxide and hydrogen gas so I'm showing you here all of the reactions that we've seen so far as you can see reacting a metal with water produces a metal hydroxide which is an Alkali and hydrogen gas calcium reacts with water in a very similar way so I'm showing you that reaction here we make calcium hydroxide and hydrogen gas calcium reacts fairly rapidly with water but it's not as rapid as pottassium sodium or lithium so as you can see as we move down this list the metals react less rapidly with water by testing a whole range of different Metals with water we can work out the reactivity of the metals I'm showing you the reactivities of the different Metals with water here potassium sodium and lithium react very rapidly with water at room temperature calcium reacts quite rapidly with water at room temperature magnesium zinc iron and copper have got no reaction with water at room temperature so we can use the reaction with water to determine the reactivity of potassium sodium lithium and calcium but we cannot use water with magnesium zinc iron and copper as they don't react with water so if we want to compare the reactivity of these last four metals then we need to react them with dilute acids we're going to look at reactions of metals with acids in later video so here are the reactivities of the metals with dilute acids firstly we'd never react potassium sodium or lithium with acid as they'd react too vigorously and that would be dangerous calcium reacts extremely vigorously with dilute acid magnesium reacts rapidly zinc reacts quite rapidly but it's less rapid than magnesium finally ion reacts slowly with dilute acid and copper does not react with dilute acid so what we've created here is called the react it series for metals and we're going to be using this a lot in the next video now scientists usually include two non-metals in the reactivity series because they're used a lot in chemistry and these are carbon and hydrogen I'm showing you these here I should point out that you're not expected to memorize the reactivity series but you could be asked to construct one from data on how elements react Okay so we've seen that different metals have got different reactivities but what actually determines how rapid a metal reacts let's look at this now the first key fact is that when metals react they lose electrons and they form a positive ion so this shows potassium forming the potassium ion k+ and losing one electron the reactivity of a metal depends on its ability to lose electrons and form a positive ion so looking at the reactivity series again we can see that Metals at the top such as potassium readily form a positive ion whereas Metals towards the bottom such as copper are much less likely to form a positive ion remember you'll find plenty of questions on the reactivity series of metals in my revision workbook and you can get that by clicking on the link above okay so hopefully now you should be able to use the reactions between metals and water and metals and acids to create a reactivity series you should then be able to describe in terms of electrons what happens when metals react [Music]