Video instructions and help with filling out and completing Which 8850 Form Relating

Instructions and Help about Which 8850 Form Relating

Let's talk about how to write chemical formulas for ionic compounds so what this means is we're gonna start with a chemical name like magnesium chloride and learn the steps that we have to go through to take this chemical name and use it to write a chemical formula like mgcl2 okay let's start with our first example lithium oxide so when I'm doing these kind of problems the first thing that I want to do is find both these elements on the periodic table I'm using this kind of weird version of the periodic table that I just wrote out I left out a lot of the elements because they're not important for what we're doing here and I thought that are kind of distracting but don't be confused this really is no different from the periodic table that you probably have in your book it's just that it's missing a lot of the elements anyway lithium I want to find that it's right here Li and oxide oxide is just another word for oxygen it's what we call oxygen when oxygen has a charge I'm going to talk a little bit more about that later anyway oxide is just another word for oxygen and oxygen is over here they're on opposite sides of the periodic table and check this out too there's this big thick staircase that separates lithium from oxygen what's a staircase doing well if you remember the staircase separates the metals on this side of the periodic table from the nonmetals on this side of the periodic table so lithium is a metal and oxygen is a non-metal this is important because we have a metal and a nonmetal connected together and that means that we're dealing with an ionic compound ionic compounds are always metals and nonmetals so when we have metals and nonmetals making an ionic compound that means that the atoms in that compound have a charge so I want to find out what the charge of those atoms is and I can do that by looking at where they live what column they live in on the periodic table here's what I mean so lithium lithium lives in this column everything in this column has a plus one charge so I'm gonna write this right here Li one plus everything in this how column has a two plus charge three plus charge you might want to write this on your own periodic table that you have for your reference everything here has a three minus charge and oxygen which lives in this column has a 2 minus charge so I'm gonna write it right here so Li 1 plus O 2 minus ok so now I ask myself does the plus charge and the minus charge balance when I have one atom of both of these the answer is no because I have one plus charge but I have two minus charges so the charges don't balance but I want to figure out how to balance them I need to have them balanced in order to write the chemical formula so what I can do is I can add more lithium atoms I can add more oxygen atoms or I can add both of them until I get the charges to balance out I have two minus here and only one plus here so what I'm going to do is I'm going to add another lithium atom li plus so that now I have two positive to balance out my two negative and now they're balanced so in order to get the charges balanced I have to have two lithium's and one oxide or one oxygen now when I write the chemical formula I'm literally going to say how many of each of these atoms I need in order for the charges to balance and we've said that's two lithium atoms so I'm gonna write Li and then the two after it that indicates that I have two lithium atoms and then one Oh to show that I have one oxygen and I'm not going to write anything after that if you have a letter without anything after it it means that you just have one of them so lithium oxide two lithium's and one oxygen is how we get the charges to balance for this compound here's the next one potassium nitrite just as before I'm going to take out the periodic table and I'm gonna find both of these guys on potassium is K it's right over here and nitride is what we call nitrogen when it has a charge on it and so nitrogen is over here check it out metal nonmetal separated by this big thick staircase and we know we're dealing with an ionic compound and whatever we think I own a compound metals and nonmetals we want to think charges what charges did the atoms have potassium lives in this column here the same column is lithium and so it has a one plus charge so I'm going to write that up here k+ and nitrogen lives in this column where everything has a minus three charge so here we have n 3 minus what I have one atom of k+ and 1 atom of n3 - do the charges balance out here the plus and minuses balance out it doesn't I've got 1 plus I've got 3 - that doesn't balance right but I can add more atoms of either type in order to get the charges to balance so since I don't have as much + as I have - I'm going to add a bunch more potassium here I add another now I have 2 + and I'm gonna add one more now I have 3 plus the 3 + potassium on this side balances out the three - nitride on this side now when I write my chemical formula I want to literally say how many atoms of each type

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