Naming Ionic Compounds with Transition Metals Practice Problems

In this video we are going to do five

practice

problems

, we will take the chemical formulas of the

compounds

that contain

transition

metals

and we will write names for them. Now

transition

metals

are the elements in this part of the periodic table here and I. I have written about some of the most common metals. I'm also going to talk about some of the metals here that are not technically transition metals, but act very much like transition metals in certain ways Now that we write down the names of formulas that contain transition metals, those names are often they have roman numerals and we have to figure out what roman numeral to put in there so we'll be really good at that now if you need a little background before we get into this video.

I recommend that you watch my video on how to name

ionic

compounds

with the introduction of transition metals and also watch my videos on how to write

ionic

formulas, if you're okay with that background, let's get started. Here's our first example, crbr2, so CR here is chrome, it's a transition. metal and like many transition metals, chromium can produce a variety of ions with different charges. Chromium can produce three ions, it can produce CR2 plus cr3+ and CR 6 Plus, so when we name this compound we have to figure out what charge chromium has here. 2+ 3+ or 6 Plus that's how we figured it out.

The first thing we will do is focus on the ion with a defined charge. The ion can only have one charge that does not change and here that is br br. is in this column this column of one minus, which means that in an ionic compound BR always has a charge of 1 minus now, how much total negative charge do we have here? Well, there are two after BR, which means we have two BRS in this compound. so let me write another one and each of these BRS has a charge of one minus, which means the total negative charge here is 2 minus, okay, that's negative charge, what about the positive charge?

Well, in an ionic compound you always have to have the positive and negative charges are balanced, which means if we have two less here, we have two more here because they balance out. Now we can calculate the charge of chromium. We have a card here. There is no number after this. means that we only have one chromium is our positive ion and we have two more of positive charge, which means that this chromium ion has to contain all this positive charge because we only have one, which means that the charge of chromium is 2+ so we have a chromium 2+ that gives us two more charges that are balanced by two less charges that are contributed by two less BRs, which means that the charge on chromium is 2+ and we can call this compound chromium now we need to say what your load is and we do this using Roman numerals in parentheses so it's CR2 plus so we're going to use the Roman numerals for two so there's 2 and now what do we call BR here?

Well, the negative ion BR minus is called bromine bromide, the neutral compound is called bromine, so when it becomes a negative ion we change the ending to ID, so the neutral version is bromine and that changes to bromide, so it will be chromium bromide 2, just a quick tip, don't get confused with these two, some students think that is the number that should come after chromium here, but that is not true, they both refer to charge of chrome, let's look at some more examples, okay, au2s, so Au here is gold and gold is capable. To produce two different types of iron ions, gold can produce A+ and a3+, so we have to figure out what charge this Au has.

We'll focus on s s is in this column of the periodic table which means it always has a charge of 2. minus so here we have S 2 minus now there's only one s there's no number after that s so that means our charge total negative in the compound is 2 minus this 1 S2 minus here now for the positive charge, the positive and the negative have to balance, that means on this side we have to have 2 more positive charge now, what is the charge of gold in Au? Well, these two tell us that we have two gold ions in the compound here is one here is the other and this 2+ is distributed between these two ions, which means that each one, since we have two of them, will be Au 1 +, so now we have two au1 plus giving us 2 plus total positive charge offset by 2 minus negative charge from our s a minus, so we discover in this case that our charge on the gold is one plus, so we do it we'll call gold and then we'll use the Roman numerals gold one in parentheses and for S when s is a negative ion S2 minus we call it sulfur as a neutral element, it's called sulfur and then we add that ID at the end when it becomes a negative ion, like this That again here in parentheses refers to the loading of gold, it has nothing to do with it. with a number after gold, okay, let's make a couple more CO3 N2 So Co, here is cobalt and cobalt can produce two different ions, it can produce a co2+ ion and a CO3 plus ion, what is its charge here, Let's find out, we'll focus on on N which is in this column here, which means that your charge on an ionic compound is always n 3 minus now What is the total negative charge here?

Well, this is N2, which means we have two of these, so I'll add an extra one now. we have two and this means that our total negative charge is 3us plus 3 minus which gives us now 6us for the positive charge, the positive and the negative have to balance each other which means we have a total of six more here now for the cobalt. Co we have three of them, let me draw them here one 2 three so how are we going to divide this 6 Plus between the three cobalts? We will do it so that each of them has two more charges and that means that in this chemical compound cobalt has a charge of 2+ so to name it we will call it cobalt, here the Roman numerals in parentheses are 2 because that is its charge here and finally N3 minus we call it nitride, the neutral element is called nitrogen and then we add that.

ID Cobalt Nitride 2, let's do a couple more. These might be a little more challenging, so they're probably worth checking out. of ion always forms one ion two more because there is only one possible ion, we don't need to use those Roman numerals in parentheses so we just call it zinc oxide, we don't call it zinc oxide 2, now there is another element in the periodic table is a transition metal that only produces one type of ion and that is silver, which always produces AG 1+, so if you are

naming

a compound that contains zinc or silver even though they are transition metals, it is not necessary to use Roman numerals because Now they can only produce one type of ion, so far in all our examples the negative ion has been a single element bromide, sulfide or nitride, but it is also possible for transition metals to form compounds with polyatomic ions which are groups of atoms that together They have a charge, so I want to do an example where we have to calculate the charge of a transition metal that is in a compound with one of these polyatomic ions.

Here's our last V, then in parentheses co32, so V here is vadio. which is a transition metal that is capable of producing four different types of ions 2+ 3+ 4+ and 5+ now the CO3 here is a polyatomic ion it is the polyatomic carbonate ion so how did I know? Well, obviously I wrote the question, but this is a good example of when it makes sense for you to learn polyatomic ions so that if you see them in a problem like this, you can recognize them immediately, so to calculate the vadium charge we need to focus first in the carbonate. our negative ion, so the carbonate CO3 has a charge of 2 minus, okay CO3 2 minus these parentheses and the two on the outside tell us that we have two of these carbonates, so let me write another one here CO3 2 minus and that means that for the total negative charge Here we have 4 minus, now that 4 minus has to be balanced with 4 more of positive charge and that positive charge will end up in this vadium.

There is only one of them. There is no number after it, so there is only one. That means. that this vadium has to contain all the positive charge, so it is vadium 4 plus, so we are going to call this compound vadium now the Roman numeral for four may be a little unfamiliar to you, it is IV, it is a good idea to memorize AR Roman numbers at least up to seven, which is probably the highest ion you'll ever see, so vadium IV for four and then as we said, this uh co32 minus ion is carbonate, so the name of this compound is carbonate vadium 4, this four is a charge of vadium, this is how we take the formula of a compound containing transition metals and how we write a full name for it with these Roman numerals