one of the things in quant that i think students think they remember entirely more than they actually do is balancing chemical equations naming stoichiometry forming ionic compounds and so i want to remind you in this video of the concepts that are go behind all of that stuff i just named so for instance right now we have this compound here so what is the name of that so nh4 remember is a polyatomic ion which means it's a group of atoms covalently bound together that have a charge and so that charge allows it to ionically bond with another atom or molecule in this case it's bonding with carbonate which is another polyatomic ion and so your carbon is bound to your oxygen covalently bound together net charge on that compound so when carbonate with its two negative charge bonds with ammonium ion which has a plus one charge you're gonna need two ammonians to bound two ammoniums to balance out the one carbonate okay so polyatomic ion polyatomic ion they're bonding through an ionic compound through an ionic bond here you have your lead and your nitrate now remember lead is a transition metal it is a type 2 and so when you're naming type 2 ions you have to tell me what the charge is why because lead has two oxidation states it has a two plus and a four plus and so when we're naming this compound we know nitrate has a negative 1 charge and so since it has a negative 1 charge this means that lead has a 2 plus here and so this becomes lead to nitrate so in naming them we would label them as like ammonium ammonium is the ion so ammonium carbonate ammonia is the gas nh3 carbonate and then this is lead two nitrate all right so that's the first step is naming and figuring out what compounds are in them but then also how are these formed so remember when we've got ammonium we have nh4 plus and carbonate co32 minus lead to plus remember your cations which are the positively charged species are written first and then the negatively charged species which is called your anion so your nitrates no3 negative so whenever we form these compounds we are crossing the charges that's what i call it and so your positive comes down your positive one comes down here and forms this kind of understood one outside of carbonate i don't write the understood ones you're welcome to do so um and then the two becomes this two that you saw in the formula of ammonium carbonate and so that's where you'll ever hear me say cross those charges that's all that means because then this becomes nh4 with a 2 outside of it and carbonate with a understood one outside of it and you do the same thing here and so that's how i knew that my lead was a 2 plus as opposed to my 4 plus because if this were a 4 outside here it would have been 4 plus but now what do we do with this how do we predict the products of my equation and so i'm just going to react them how they would form if they were put into water and then find the different ions so in order for me to do this that's going to assume that this is aqueous and this is aqueous if i'm going to put them into water so what do i mean by aqueous ammonium ions are highly soluble so are nitrates those are very soluble if you remember your solubility rules so you throw them into water they're going to force these guys to come apart these guys come apart and now they're free to go and find other species that might be interested in bonding so if another positive finds another positive so if my lead finds my ammonium they're going to repel because they're both positively charges same thing for carbonate and nitrate repel but if my ammonia forms with my nitrate they're going to find and they're going to stick and may be momentary and they may fall right back apart or they may stick and form a solid and then carbonate and lead is going to do the same and so if these form what compounds are formed so we need to do what we talked about a second ago which is crossing those charges so we have nh4 reacting with my nitrate so these two are going to react and then also my lead 2 plus is going to react with my carbon h so when these two react together i'm going to cross those charges and form nh4 and put my parentheses around there just for me no3 and then my charges are not written in the final product and my next one i got to cross those charges but when i cross them this 2 is coming down here this 2 is going to come down here and then you report it in its lowest common form and so the 2s are essentially going to go away and reduce down to be ones and so i end up with lead to carbonate which is just written like that so now to finish out my reaction i'm kind of ran out of room going right so just assume this half is the first half of my equation and then this is my second half of my equation what are my states here well ammonium ammonia excuse me is very soluble so is nitrate so this is going to be aqueous and then lead carbonate that is going to be insoluble a lot of your carbonates are not soluble so especially if you mix them with the transition metal and so this one is going to be your guest best guess if you had to guess and that is your solid substance okay so what do we learn here we remind ourselves about polyatomic ions remind ourselves about ionic compounds and how we form them predict products remind ourselves a little bit of solubility all this is built into balancing now in quant we're mainly working in the liquid state okay we're not doing a whole lot of just creating synthetic compounds um from mixing compound solids together so a lot of ours is in the aqueous phase so in this case when you think about what are spectator ions what is the net reaction so we're talking about net reactions is what if this stuff formed my compound what compound do i care about well this is the only real compound that's formed what do i mean by that if these are aqueous that means that my ammonia and the ions are still floating around in water so are my nitrates and so if they're still floating around all of this is happening but this is the only new thing that's formed it forms it sticks together that's why we have a single right arrow forming to the right and so my neck compound would then of course be fled two plus plus my carbonate yields i ran out of room so i'm going to come just below it lead carbonate that looks like that and so this is my net reaction i put my states in here aqueous aqueous and solid this is what really happens this is the reaction i care about all the other stuff normally your group one you know cations those are just spectators and so ammonium and my nitrate those are my spectators and so we need to be paying attention to what's happening and why but then also what is the equation because a lot of times students just don't write out the chemical reaction and if they would just write it out they would do fantastic so that is your first idea is the balanced chemical equation and all the stuff that goes into creating that net reaction