in today's video we're going to take a look at ionic compounds with a focus on how they're structured what their properties are and how we can determine their formula if you remember ionic bonding it generally involves a meta atom like sodium transferring one or more electrons to a non-metal atom like chlorine to form two oppositely charged ions and these two ions will then be attracted to each other by electrostatic forces forming an ionic bond and we call the entire thing an ionic compound in real life though ionic compounds generally involve tons of ions not just a couple like we showed at first and the positive and negative ions alternate so that each ion is attracted to all of those around it and as this happens in all directions it would actually form three-dimensional structures that we call regular lattice structures so in our drawing here the green ions represent the positive sodium ions and the red ones are the negative chloride ions we can also represent these ionic compounds with ball and stick diagrams where we showed the different ions and put lines between them to represent the ionic bonds next up we need to take a look at the properties of ionic compounds specifically that they have very high melting and boiling points and that they can conduct electricity but only when they've been melted or dissolved in water if you think about any substance the melting and boiling points are determined by the strength of the bonds holding that substance together in ionic compounds there are loads of ionic bonds all of which are really strong so to break them all would require loads of energy which is only going to be available at very high temperatures when it comes to conducting electricity though the important thing is whether there are any charged particles that can move and these could either be ions or electrons when ionic compounds are in their solid form everything is fixed so they can't conduct any electricity however when they're melted or dissolved in water the ions are free to move about and this movement of charged particles allows them to conduct electricity the last thing we need to look at is how to determine the formula of an ionic compound when we looked at sodium chloride earlier we saw that the sodium had a one plus charge and the chloride had a one minus charge so to balance each other out and become neutral when they combined we just needed one of each and so the formula would be nacl if we had magnesium chloride though then it would be a bit different because magnesium is in group two so when it becomes an ion it loses two electrons to become a two plus ion so this time to balance out that two plus we need two of the chloride ions which are each one minus meaning our formula would be mg cl2 we can also do this with more complicated compounds like calcium hydroxide or aluminium sulfate these ones are harder because the hydroxide ions and sulfate ions aren't single elements so we can't look them up on the periodic table instead you have to memorize their formulas and charges hydroxide ions are oh minors and a sulfate ion is so4 2 minus with this in mind let's take another look at calcium hydroxide calcium is in group two so we'll have a two plus charge and we just said that hydroxide has a one minus charge so for each calcium we're going to need two hydroxide ions giving us the formula ca oh2 and notice that we put a bracket around the entire hydroxide ion this is so that the little two in the bottom right tells us that we want two entire hydroxide ions not just two hydrogens for aluminium sulfate though we have a three plus aluminium ion because aluminium is in group three and a 2 minus sulfate ion which is a bit awkward because we can't just increase the number of one of them to make the two charges balance so here we need to find the lowest multiple that two and three have in common which would be six so to get a positive six charge we'd need two of these aluminium three plus ions and to get a negative six charge we need three of these two minus sulfate ions so now that we have two three plus ions and three two minus ions the charges balance out and the overall formula would be al2 so4 3 now just like hydroxide and sulfate ions there are a few other ions worth knowing such as the nitrate ion which is no3 minus the carbonate ion which is co32 minus and the ammonium ion which is nh4 plus it's probably worth noting these down or taking a screenshot as it would definitely be easier if you just remember these ones anyway that's everything for today if you enjoyed it then please do give us a like and subscribe and we'll see you next time you