this video is on chemical nomenclature so let's start with a chemical formula this tells you how many atoms are in each type of compound or molecule so we have a molecular compound which is composed of non-metals and one example here is C8 h18 those subscripts tell you that there are eight carbon atoms and there are 18 hydrogen atoms if we have an ionic compound an ionic compound is consist of cat ions which come from metals and anons which come from non-metals so here is an example of an ionic compound al2 so43 this tells you that you have two aluminum atoms and you have three what's called sulfate atoms so s so4 here this is called sulfate this is called a polyatomic ion so you will not find S so4 on the periodic table you will find an S and you will find an O but not just the box with s so4 so a polyatomic ion is when more than one element are joined together and then they have a charge associated with them which we will get to if you break if you look at these parentheses next bullet point here this three distributes in kind of like math class distributes in and multiplies by the subscript with each element so since there is a little one after the S we don't show it but there's understood to be a one 3 * one there are three sulfur atoms and there are 12 oxygen atoms for the three times the four there so as I just said Metals form cat ions cat ions are positive positively charged ions metals lose electrons they donate their electrons they give away their electrons to the non-metals so if you lose an electron you lose something negative you become positive on the opposite Spectrum your non-metals form what's called an anion an anion is a negatively charged ion if you gain electrons if you gain negativity you become more negative very similar to valance electrons the group number pretty much tells you what the charge on the ion's going to be so for memorization purposes it's pretty nice um in that regard so if we're looking at our periodic table here your group one elements these all have a plus one charge the these group two elements these all have a plus two charge our transition elements as you guessed it are kind of weird we'll skip them for now our group three elements have a plus three charge let's skip some let's go over to group 17 7A these have a negative one charge non-metals form annion negative these have a NE -2 charge these have a -3 charge and these group 4 a get a little tricky they can be positive or negative um a little trickier there but as far as Group 1 a 2 a 3A 5 a 6A and 7A you should have those memorize their charges it'll make life a lot easier you may be curious why they are those numbers the ones twos and the threes remember the goal is to become a noble gas so let's look at Florine for example for Florine to become a noble gas it needs to gain one electron to go over here so that's why it's a minus one it wants to gain one electron oxygen to get over there needs to gain two electrons nitrogen three electrons let's look on the opposite side of things lithium to become a noble gas can either gain seven or it can lose one to behave like helium so that is why lithium is a plus one because it is way easier to lose an electron than to gain seven electrons so that is why the numbers are the way they are monatomic F ions are named by using the element name so for potassium for example pottassium is K if you have a k+ and that's a one there if there's not a number it's understood to be a one that's just called the potassium ion there's nothing fancy about it your anion are named by dropping the ending of the element name and adding IDE so for example Florine you will see Florine on the periodic table ending in IE if that becomes an ion it's now a fluoride F minus and again there's no number but that's a minus one different types of nomenclature we're going to talk about binary ionic compounds transition metal and calent compounds so for binary ionic compounds these are composed of two two elements a cat and an anion something from the left side of the periodic table and something from the right side of the periodic table you need their charges to cancel out so for example if we have a magnesium ion and we have a bromide ion we need the overall charges to equal zero so how many bromides would we need to make that netive 1 cancel with a NE with a positive two we would need two of them right because two NE 1es is a -2 and then they would cancel so here notice we put a two after the BR to show that it's mgbr2 we only have one mg we don't show the one but it's understood that there is a little one here you can use something called The Crossover method if you don't want to think about like least common denominator stuff the crossover method you literally take the numbers and cross them over to the bottom notice they are going on the bottom and another really important part it's always going to be positive when you cross over you're not going to take like negatives or pluses with you it's always just a positive number so mg again it's a one so we're not going to show it and then BR is going to be a two the only issue I would say with the crossover method is when you have numbers that need to be reduced so for example let's say we have let's look at our charges chart here and this will be posted for you as well let's say we have barium carbide so if we have barium is a plus two carbide is a minus two so if we cross over 22 it's ba2 C2 but when you think about least common denominator how many Bas do you need and how many C's do you need for them to cancel to equal zero you only need one of each right you don't need two of each so you have to reduce those twos that two and two just becomes a one in one and that's only for binary ionic compounds well anything ionic you need to do that so you must remember to reduce and that would hold true if you had like a two and a four as well that would become a one and two so you always reduce that stuff so here it says write the formula for the binary ionic compound of aluminum and oxygen so again you want to memorize a lot of these it'll just speed up your time Big Time but we do have our chart here so I see aluminum is here Al +3 and oxygen is down here the endings already changed to oxide is O minus 2 so aluminum oxide cross over al23 we would need two aluminum atoms and three oxygen atoms for them to cancel if we had two + 3s that's a plus 6 if we had 3 Min - 2s that's a minus 6 they cancel different ways of looking at it the next one write the formula for the binary ionic compound of zinc and sulfur so we have zinc and sulfur got it from my chart since they are both twos reduce it it is just zns one of each of them and that would be called zinc sulfide Chang in the ending so that is right writing the formulas naming it is easier I think again the cat ion name is just the element itself as we saw with the potassium example in a previous slide so your cat ion Al is just aluminum and the Anon you just change the ending to IDE so instead of oxygen it's just oxide so here we have agcl AG is silver CL we know is chlorine but if we're changing the ending to ID we get silver chloride likewise here calcium chloride I want you guys to think of what you put on your food well hopefully you don't put it on your food but you might put on your food at dinner time take table salt right table salt is called what it's called sodium chloride it's not called sodium chlorine so we already changed that ending to IDE the next type of nomenclature is transition metal nomenclature so your transition metals again that's your middle spot on the periodic table here so they do not have predictable charges like the ones we already said to memorize these can have more than one charge assoc associated with them your transition metals on this chart you will be able to tell them because they have Roman numerals next to them so let's just look at a couple of them let's look at gold so notice gold here it says gold and then it has a Roman numeral one in parenthesis notice you'll also find gold in the plus three column and that's gold with a Roman numeral three after it it can be more than one thing let's look at copper copper can be A+ one copper can be a plus two iron can be a plus two iron can be A+ three lead can be a plus two lead can be a plus4 so your transition metals can have more than one charge associated with them so it's a little bit trickier determining which one you're using so let's look at this example here so we have cuu cl2 so when we are naming this I know that CU is copper and I know that CL is chloride however there is more than one copper there's copper one there's copper two and they're very different copper 1 chloride and copper 2 chloride are very different compounds that react very differently with different things so how do we figure out if it's copper one or copper 2 the way you do that you look at your anion so in this case our anion is CL cl's charge is a minus one so we have a minus one charge here notice how many of these CLS we have we have two of these CLS so we don't just only have one minus one we have two minus ones for a total of minus two charge here remember we need these charges to cancel so what charge has to be here to cancel a minus two well it has to be a plus two so I know that this copper is copper 2 chloride so you're working backwards to figure out which transition metal you are using writing the formulas you're still doing the crossover method or the least common denominator method that doesn't change so here it says write the formula and give the name so formula wise I'm still going to cross over crf3 naming this CR is chromium and if I'm looking on my charges chart I'm going to be very careful to make sure I see where chromium is chromium is here chromium is here so that is my Q if I see that Roman numeral like okay I have to figure out which one I'm actually using here now it's easy enough cuz it says up here already already says it's a plus three so it is chromium 3 fluide polyatomic ions we talked about these already they have more than one element in them with a charge a lot of your negatives down here are polyatomics so if you just look under the minus one column polyatomic because there's more than one element polyatomic polyatomic all of these yeah I could say most of these are polyatomics let me bring your attention to nitrate and nitrite look how similar the names are they differ by one letter and look how similar the formulas are they differ by one oxygen be very careful there's more cases like that sulfate and sulfite same idea there phosphate and phosphite phosphide so you want to be very careful when you're using these formulas let's try this example write the formula for tin4 sulfate and then give the name of nh4 okay so starting with him tin is SN this four tells us the charge of our cat ion so I know that that's a 10 + 4 then using my chart I know sulfate is a minus two remember for ionic compounds you must reduce so you can do this one of two ways you can reduce right away if you want so that four and two you can make that a two and a one so let's do that in a different color here you can say okay really that's + 2 minus one and then cross over so that would be sn1 S so42 notice I have my parentheses there I don't want s so42 I want 2 S4s so I need the parenthesis or if you cross over with the the red right away you would say sn2 s44 and then you would just have to recognize okay I got to reduce that to a one and a two either way your final answer is that and how about the name of that nh4 I believe is the only polyatomic cat Ion on this chart it's the first guy up here he's the only one on there so nh4 is ammonium and then o is hydroxide okay and the last nomenclature for this video is for coal compounds or binary molecular compounds we use the prefix system here what are binary molecular compounds these are two non-metals so all the ions we know ions come from cat ions metals and an ions nonmetals that's metal and nonmetal these are two non-metals together two things on the right side of the table depending on how many atoms you have per element you have to use a prefix that's associated with it so if you have one atom you're using the prefix mono if you have two you're you using the prefix die if you have three try so on and so forth most of these you probably know from geometry class back in the day I would say mono and Tetra are probably the weirder ones for you you're always using a prefix unless the first element in the compound only has one atom so if the first element has one you're not using mono other than that you're using it for everything the second rule here the second element should end in ID very similar to binary ionic compounds and the last little rule here is that if you have words if you have like monooxide like down here a vow followed by a vow you cut out one of those O's so it's just monoxide instead of monooxide and you're cutting out the the vowel at the end of the prefix okay but those are the three rules for this so here are some examples here so the first row N2 2's prefix is D so notice we put D nitrogen and then the O since there's not a number we know that's a one so that would be the mono with an oxygen and again we dropped an O so it's just monoxide second example the N is a one notice we did not put mono here that's the only time we don't use a prefix so it's just nitrogen and then monoxide so you can look through the rest of those and see how it worked give the name for p410 so if I am looking at that Four's prefix is Tetra and P is phosphorus 10's prefix is DECA but it's followed by an O so I'm going to drop the a in Deca and just say deoxide so Deca oxide and I dropped the a Tetra phosphorus deoxide the next one here the prefix for two is d as s is arsenic the prefix for five is Penta but it's followed by an o so I'm going to drop the a pentoxide and if I can just give you one more example here working in Reverse so here I gave you the formula and you had to write the name what if I write the name so if I said OCTA carbon hexabromide so carbon is C OCTA is8 bromide is BR hexa is six and that is how you would do that in reverse