Hi. It's Mr. Andersen and today I'm going to show you how to name chemical
compounds. And the reason we do that is when you're you should be able to pick up anything
and figure out what's actually in it. And so if we've got a can of Mountain Dew, this
is old school Mountain Dew, and we look at what's inside it, there's going to be water
and sugar. And we know what those things are. But there's also going to be, for example,
sodium benzoate. And at the end you'll actually know what that is. Or calcium disodium. You
should be able to figure that out when were done. What that actually is. And so let's
get started. First of all let's start with the rule of thumb. The rule of thumb says
that if you hold your thumb up to the periodic table things on one side of your thumb are
going to be non metals. And so if I hold it up like this, everything on this side of my
thumb is going to be a non metal. Everything on this side of my thumb is going to be a
metal. And so there are really just three types of bonds. If you have two metals together
we call that a metallic bond. If you had two non metals together we call that a covalent
bond. And then if you have one metal and one non metal together we call that an ionic bond.
And if you don't know how to figure out what kind of a bond it is, you want to look back
to the previous podcast where I talked about what exactly that is. One quick way to do
it is to just look at the differences in the electronegativities. So calcium is one. If
we look over here for example, nitrogen, that's 3.04, so I should be able to tell right away
that that's going to be an ionic bond, just from the electronegativities. Okay. Let's
start with the easiest one. And that is naming covalent compounds. First of all you have
to figure out how do I know which of the two atoms comes first. In other words why is it
carbon dioxide and not dioxygen mono carbon, excuse me, carbide. So let's look on the periodic
table and I'll talk about rule one and rule two. Rule one says you always start with the
lower group number. And so why is it H2O? It's because hydrogen has a lower group number
than oxygen, which is over here. And so hydrogen gets to go first. Now you might immediately,
if you're smart be thinking, well, okay that works. We're always going to go kind of from
left to right. But what if they're in the same column? And so sulfur dioxide is an example
of that. We've got sulfur here and we've got oxygen right above it. So who goes first?
Well you're always going to start with the one that has a greater period number. And
remember period numbers are going to increase as we go down the periodic table. And so sulfur
goes before oxygen just because it's lower on the periodic table. So once we figure out
who goes first, then it's really easy to figure out the names of these. So let's start with
carbon dioxide. Carbon dioxide, carbon is going to go first. Whenever you're naming
covalent compounds, you're just going to put the name of the atom first and then you're
going to put the anions second. These little subscripts tell you how many of those ions
you actually have. One more thing, so first of all we put the atom first and then we put
the second as an ion, or in this case it's a negative ion called and anion. And then
we're just going to use this chart over here to figure out how many of them we have. It
goes from mono meaning one all the way up to deca meaning ten. We rarely use these ones
down here. But you might as well learn these first four because we use those quite a bit.
So let's start with carbon dioxide. Now you might want to say well there's only one carbon
and so let's call that mono carbon. But you can see here that you don't put a mono on
the first one. Also if we have like mono oxide, that sounds kind of silly. You just kind of
lump that together and that would be monoxide. So let's start with the first one. So we've
got carbon first. So we're just going to write the name of that element. So carbon is first.
And then we have two of the oxygens. And so that's going to be dioxide. And you've heard
that before. Carbon dioxide. Let's look at the next one then. What's the first element?
The element is going to be, P is going to be phosphorus. And then we have N next. Now
it's not nitrogen. It's going to be the ion of nitrogen. So let's kind of skip forward
and see what that is. It's way up here. Let me get in a color you can see. It's going
to be nitride. And so if you're ever trying to figure out what the ions are, you can look
on our, we use the in class, Periodic Table of Ions. And it's going to tell what the name
of that is. So let's go back and finish this one out. So this one, we have phosphorus,
but we have three of those. And so this one is going to be triphosphorus. And then we've
got four of these nitrides. So that's going to be tetranitride. So that's the name of
P3N4. If you go to the next on this is carbon, so we're just going to write the name first.
Carbon. And then we've got four of these hydrides. And so that's going to be carbon tetrahydride.
So if you look at this again, we're always writing the atom name first and then we're
always going to write this, instead of tetrahydrogen it's going to be hydride. We're going to write
that anion for that. So that's naming covalent compounds Let me erase that and let's go to
ionic compounds. Ionic compounds, it's actually easier. There's just two rules. Rule number
one, you're always going to write the cation first and the anion second. So you're always
going to write the positive charge first and the negative charge second. And the only other
tweak on that is that there are some elements, let's kind of skip back for a second. So if
you look way over here. Let's look at for example iron. Iron, you can write iron in
a number of different ways. We can have iron III. We can have iron II. Some of these will
have multiple states that they can have. And so if there ever could be more than one type,
like iron III or iron II, in Roman numerals we're going to note which one of those are,
which one they are. And so let's take a look at one of these and actually do that. So let's
look at the first one. So this lithium and oxygen. And so all we do is look on our chart
and we figure out what the name of those ions are. So if we go back and here, here's lithium
all the way over here. So lithium is going to be the name of the cation. And then we
go over here and we find the anion. And it's just simply lithium oxide. And so this one
would lithium oxide. Now if you look at it, why is it written as Li2O? Because lithium
has a positive charge and oxygen or the oxide anion is going to have a 2 minus charge, so
we have to have 2 of the positive charges to balance that out. Now let's look at the
next one. This one looks a little bit scary. What this one, you shouldn't be scared though.
If we ever see something that is written in parenthesis, that means that it's a polyatomic
ion. That means it's an ion. It still has a charge, but it's made up of more than one
atom. In this case we have NH4. So let's just go back to our chart and find out where that
is. I'm going to look around here until I find it. So it's way over here. So this would
be NH4. And that stands for ammonia. And so that's going to be ammonia. And now let's
look back at what we had. And now we have a P. And so that's the other part. That's
going to be our anion. So let's find that. That's going to be phosphide over here. So
if we look at ammonia there's only one type it can be. NH4 and phosphide is going to be
P. And so let's just kind of go forward and write that as it is. So that is ammonium phosphide.
So again, pretty easy. We're just writing the cation first and then the anion second.
Now let's look at this one. We've got copper. And then it looks like we have another one
of those polyatomic ions. In this case it's going to be an anion. So let's go find it
on the chart. First of all we have to find copper. And so copper, I've kind of written
all over it, but copper is going to be, where's copper going to be? Copper is going to be
right here. And so copper can have two states. Copper can either be Cu2+ or it could also
be CU1+ or just plus. And so we have to figure out which one it's going to be. So let's go
take a look at that. So here we've got copper. And now we've got this. We've got to figure
out what that NO3 is. So let's go back again. So where is NO3. NO3 is going to be written
on our chart. Looks like I'm going to have to erase some of this stuff. So if we look
up here, NO3 on our chart is going to be, NO3 is going to be nitrate. And so nitrate
is going to be right here. It's NO3. And it has a 1 minus charge. And so now we've got
our copper which we know could be copper II or copper I. And now we know that nitrate
has a minus 1 charge. So let's try and figure out what this is. So nitrate has a minus 1
charge. So this is minus 1 for this nitrate right here. But we don't just have one of
them. We actually have two of those. That's what this subscript means down here. And so
on the right side of this we have two of these minus 1 charges. And so we have a 2 minus
charge on the right side. If you look on the left side, well, what copper do we have? Well
we know right away that since there's 2 minus charge on this side we actually have copper
II. So let's write that out. It's going to be copper. Now we know it's going to be copper
II. So in Roman numerals in there I'm going to put copper (II). That's going to be nitrate.
So again the only time we have to write those Roman numerals is if it could exist in two
different states. Let's go to the next one. Looks like we've got nickel here. And then
we have SO3. So figure out what SO3 is. Let's go back. So let's find SO3 on here. SO3 is
actually going to be sulfite. And it has a 2 minus charge. Now if we find nickel, nickel
can either be nickel II or it can be nickel III. So again we have sulfite and we've got
nickel. And you got to kind of switch between these. So now we've got nickel and we've got
sulfite. Sulfite remember had, sulfite had a let me go check again, had a 2 minus charge.
And so this has a 2 minus charge on this side. And we have 3 of those. And so what do we
have net on the right side? We actually have a 6 minus charge on the right side. And so
what nickel do we have? Well if look on the left side we have 2 of these. And so to balance
out that 6 minus charge on the right, it has to be nickel (III). And then on the right
side that's going to be sulfite. Let me add some dots here. And so we know that it's balanced
on either side and so we're going to call that nickel III sulfite.