hello in this video we're going to look at the three main types of bonding that you'll see in elements and compounds and we're going to look at how each type of bonding occurs the three main types of bonding are covalent bonding ionic bonding and metallic bonding covalent bonding occurs when atoms share electrons so their outer shells overlap and they will share a pair of electrons this only happens in non-metals so metals are never involved in covalent bonding there are two types of covalent bonding simple covalent which is small molecules like ch4 h2o co2 with just a few atoms in them and this makes up most of the covalent compounds so almost all covalent compounds are simple covalent there are then a few exceptions which are giant covalent compounds instead of small molecules these have thousands of atoms joined together they're still covalently bonded but there are just a few of these examples that you need to know that form giant structures ionic bonding is not sharing electrons it's giving and taking electrons this happens when you've got both metals and non-metals together you must have at least one metal and at least one non-metal and when they react together they form this giant ionic lattice of positive and negative ions and finally metallic bonding occurs only within metals so non-metals are never involved we've got the positive ions and the delocalized electrons so we'll start looking at covalent bonding covalent bonding happens only in non-metals so we never have metals involved in covalent bonding and it happens when two non-metal atoms or more than two share a pair of electrons so here we've got two chlorine atoms their outer shells are overlapping and they are sharing a pair of electrons this shared pair of electrons is a covalent bond and it joins the two atoms together it's a very strong ones and it holds them together so this xo in the middle is a shared pair of electrons and that is the covalent bond between the two atoms this is a simple covalent molecule we have the simple covalent and we also have giant covalent simple covalent molecules are things like chlorine cl2 hydrogen chloride or hydrochloric acid water oxygen and carbon dioxide so you can see these are all elements or compounds that contain one two three maybe four atoms but anyway it's only a few so when you've just got a few atoms in a molecule that's a simple covalent molecule giant covalent on the other hand is when you've got many thousands of atoms joined together three examples of this would be the allotropes of carbon diamond graphite and graphene instead of just three or four carbon atoms you've got hundreds or even thousands of atoms joined together in a giant structure the one other example of this you need to know is silicon dioxide you just need to remember these four examples so if it's covalent if it's not one of those four examples you can assume that it's a simple covalent compound here are some practice questions for covalent bonding number one what is a covalent bond number two which types of elements form covalent bonds and number three which of these compounds has a simple covalent structure we've got sodium chloride iron diamond sulfur dioxide and oxygen pause the video and have a go at these questions a covalent bond is just a shared pair of electrons it's a pair of electrons that are shared between two atoms when their outer shells overlap as shown in this diagram so in this diagram it's the xo pair in the center of the two atoms that is your covalent bond covalent bonding can only occur between elements that are non-metals either two atoms of the same element or it can be different elements they have to be non-metals and of that list the only ones that are made of non-metals only are the last three but diamond is one of those examples where it's a giant covalent whereas sulfur dioxide only has three atoms and it's covalent so that's going to be simple covalent and then oxygen o2 again we know it's covalent because oxygen is a non-metal and because there are only two atoms in that molecule it's going to be a simple covalent now we're going to look at ionic bonding which is a little bit different to covalent bonding this happens when you've got both metals and non-metals it won't work unless you've got at least one of each metals and non-metals reacting together and this time instead of sharing electrons they gain electrons and lose electrons so here we've got a magnesium atom which has lost two electrons so it's formed a magnesium ion with a two plus charge a positive charge that is our metal ion and then we've got an oxygen atom has gained two extra electrons to form a negative oxide ion and that is our non-metal so we've got a metal and a non-metal reacting together because one ion is positive and the other is negative there'll be an attraction between them and that attraction is our ionic bond so the definition of an ionic bond is a strong electrostatic attraction that is a really really important key phrase that just means attraction between positive and negative and in this case it's between positive ions and negative ions so we have have our positive and negative ions arranged like this in this big crystal structure and this would happen thousands and thousands of times over with thousands of atoms and there's that attraction between positive and negative ions that is your ionic bond that strong electrostatic attraction this structure where you've got thousands of ions repeating in that structure is called a giant ionic lattice some examples of ionic compounds will be calcium chloride magnesium oxide and aluminium bromide so you can see in each of these chemicals if you look at their formulas we've got a metal and a non-metal so calcium is a metal whereas chlorine is a non-metal in magnesium oxide magnesium is a metal and oxygen is a non-metal and in aluminium bromide aluminium is a metal and bromine is a non-metal so you can see in each case we've got both a metal and a non-metal element present at least one of each you could have more than one of each it will not be ionic bonding unless you've got both a metal and a non-metal present here's some practice questions about ionic bonding this time so number one what is an ionic bond and no this one's a two mark question number two which types of elements form ionic bonds number three which of these compounds are ionic there's just one in this case we've got sodium chloride iron diamond sulfur dioxide or oxygen pause the video and have a go so the definition of an ionic bond is that it is a strong electrostatic attraction electrostatic is about positives and negatives this time it's between positive ions and negative ions the positive and negative ions are attracted to each other that's the dotted lines in this diagram those are your ionic bonds the types of elements that form ionic bonds are metals and non-metals you can only get an ionic bond forming if you have a metal and a non-metal reacting together and of those compounds and elements sodium chloride is the only one that has a metal and a non-metal present sodium and chlorine so that means that must be the only one that's ionic the last type is metallic bonding and this happens obviously only within metals so it happens inside a sample of a metal or between metals the metal atoms lose electrons out of their outer shell and that makes them form positive ions the electrons they lose become delocalized which means they're no longer attached to any one ion and they kind of float around in this sea of delocalized electrons we've got positive ions and then a sea of delocalized electrons floating around between them because the ions are positive and the electrons are negative there's going to be an attraction between them just like with ionic bonding they're going to be attracted to each other and this attraction between the ions and the electrons is the metallic bond so the definition of a metallic bond is a strong electrostatic attraction so it's the same key phrases with ionic bonding but this time instead of between positive ions and negative ions it's going to be an attraction between the positive ions and those negative delocalized electrons and that attraction holds the metal together and it helps it keep its structure the positive and negative are attracted to each other and that holds the metal together this is what this giant metallic structure would look like so again in this case just like ionic bonding you've got many thousands of atoms joined together in rows forming this giant metallic lattice being held together by that attraction between the ions and the electrons so examples of metallic substances would be magnesium calcium aluminium copper sodium and iron so things that are on the left of the periodic table and some final practice questions for metallic bonding number one what is a metallic bond number two which types of element form metallic bonds and number three which of these compounds is metallic pause the video and give these questions a go the definition of a metallic bond is that strong electrostatic attraction that gets you first mark and this time it is between the positive ions and not negative ions it's the negative delocalized electrons so that's how it's slightly different to ionic bonding so instead of between positive and negative ions it's between positive ions and negative electrons the attraction between them is your is your metallic bond it only happens within metals never between non-metals and of all those compounds iron is the only one that is comprised only of a metal so that is the only one that is metallic thank you for watching i hope this video has been helpful for you and i will see you in the next one bye