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in this video we're going to go over
the nomenclature of ionic compounds
particularly those that have polyatomic
ions and
transition metals
so you need to know the names of certain
polyatomic ions
so let's say if you have so3 2 minus
this is called sulfite
let's review some polyatomic ions
so4 2 minus
this is called sulfate
s2 minus is a monoatomic ion
and monoatomic ions they typically end
in ide instead of i or 8.
so this is called sulfide
what do you think the names
for these ions are
po4 three minus
is known as
phosphate
po3 three minus
is called
phosphite
eight usually has one more oxygen than i
and p minus three that's a monoatomic
ion
it's phosphide
what about these clo4 minus
clo3 minus clo2 minus
clo minus and cl minus
clo4 is called
perchlorate
clo3
is chlorate
clo2 minus is chlorite
clo minus is hypo
chlorite
and the monoatomic ion cl minus
is chloride with an ide
suffix
now there's some other ions that you
should know
feel free to pause the video and write
the names of these ions and see if you
have the correct answer
oh minus is known as
hydroxide
co32 minus
is called carbonate
no3 minus
is nitrate
no2 minus nitrite
which has one less oxygen than eight and
this is called acetate
see if you know these
cr042 minus is known as chromate
cr2o72 minus
is called a dichromate
mno4 minus is permanganate
and cn minus
is cyanide
and c2o2 minus is oxalate
now let's go over some examples let's
say
if you want to name the compound
nacl
how can you do
it so the first atom and a you simply
need to write the name
n a is known as sodium
now cl is chlorine but instead of saying
chlorine you want to say chloride
for the last part you need to add the
end in ide
so nacl is composed of sodium ions and
chloride ions
here we have a monoatomic anion
and cl minus is known as chloride
now let's say if we want to name kclo3
the first element k is simply called
potassium
the second part the polyatomic ion you
simply just need to know what the name
is
clo3 is called chlorine so this is
potassium chlorate
go ahead and write the names
of the following compounds
so what's the first one
the first element n a is called sodium
and co3
is the carbonate polyatomic ion so this
is called sodium
carbonate
for the second one mg
is magnesium
and we simply have s which is a
monoatomic ion so it's going to have the
end in ide
so it's magnesium sulfide
ba is known as barium
and so4 two minus is a polyatomic ion
called sulfate
so it's barium sulfate
and the last one
a l
is aluminum
and the o h part
is hydroxide so combined it's simply
aluminum hydroxide
well i'm sure by now you must be saying
to yourself it can't be that easy
and there are some harder examples
particularly with the transition metals
where you have multiple oxidation states
for example
how would you name
fecl2
and fecl3
now it turns out that fecl2
is called iron
to
chloride
and it's not necessarily because
there's a two here
what it really represents
is the oxidation state or the charge on
fe
now chlorine as an ion has a negative
one charge
and because of the subscript there's two
chloride ions
so fe
needs to have a charge
that balances those two negative charges
the total negative charge is negative
two and we only have one fe particle so
it has to have a charge of plus two
to neutralize the total negative two
charge
by the two chloride ions
so therefore it's called rn2 chloride
fecl3
is known as iron iii chloride
because the charge on iron
is plus three
it has to have a charge of plus three to
neutralize
the
three chloride ions which has a net
charge of negative three
and so that's how you can write
the name
for
an ionic compound that has a transition
metal with multiple oxidation states
you need to use the roman numeral to
specify
the charge of the metal
so let's go over the roman numeral
system
this represents one
this number is two
and this number is three
now if you see a v
v represents five
now if you see like an i that's to the
left of the v
that means five minus one which is
really four
now if you see an i symbol to the right
of the v instead of the left
it's five plus one which correlates to
six
and if you see this that's five plus two
which is seven
now let's go back to fe
how would you name
fes
and
fe 2 s3
now notice that the coefficient is 1 but
it's not rn1 sulfide it turns out
this is called rn2 sulfide
and the reason for that
is because the charge on sulfur is
negative two
and therefore the charge on f e must be
plus two to balance it because
they exist in a one to one ratio
now if you seem confused by this
you can write an equation to solve for
the oxidation state of f e
so it's going to be f e plus s is equal
to zero
the zero comes from the fact that the
net charge of this compound is zero it's
neutral overall
now to find the answer
to solve for f e you need to know the
charge on sulfur
so you need to know the common charges
of the monoatomic ions
sulfur has a charge of negative two when
it's the most electronegative element in
the compound
so to solve for fe you need to add two
to both sides and you can see that
f e has a charge of plus two
so now what about the example on the
bottom
what is the oxidation state of fe in fe2
s3
so let's write an equation 2fe
plus 3s
is equal to 0.
the charge on sulfur we know it to be
negative two
so three times negative two
is negative six
and let's add six to both sides
so at this point
we can see that
two f e
is equal to positive 6.
so if we divide both sides by 2
f e
has a charge of 6 divided by 2 which is
plus 3.
so it's in the plus 3 oxidation state
so now we can write the name of the
compound so we know it's iron
3
sulfide
since fe has a plus 3 charge
sometimes the oxidation state is going
to be this number sometimes it's not
so don't always rely on it but it's a
possible it's an indicator that it could
be plus three
just not all the time
now let's go over the charges of certain
monatomic ions
the group one metals like sodium
lithium potassium
even hydrogen
which is a non-metal
the elements in the first column
typically form
ions with a plus one charge
the elements in the second column
like calcium
magnesium strontium
these two
or three they form charges
that are of the plus two magnitude since
they have two valence electrons by the
way lithium is above sodium so i really
didn't put this in order
then in group 3a which is like group 13
on the periodic table
you have elements such as aluminum
gallium
and these guys they form
ions with a plus three charge
now the group 4a elements
such as silicon
germanium
10
lead
typically they form plus two and plus
four oxidation states
and then you have elements like nitrogen
and phosphorus
these elements like most non-metals they
like to acquire electrons so they like
to form
ions with a negative three charge and
then you have the calcagens like oxygen
sulfur and selenium
they like to form a minus two charge and
then the halogens
which are very reactive non-metals like
fluorine
chlorine
bromine and iodine
they form negative one
charges
so knowing that information can help you
to determine the oxidation state
of
a transition metal
so let's try
these examples
name
pbo and pbo2
so pb stands for lead
o is oxide as a monoatomic ion
so we have lead oxide
we just need to know what the oxidation
status for this particular substance
so if we write an equation pb plus
oxygen equals a net charge of zero
we know that oxygen has a charge of
negative two
so if we add two to both sides we can
see that pb
is in the plus 2 oxidation state
therefore to name it
it's going to be called
lead
2
oxide
so now what about the other compound
well let's write an equation
so we have pb plus two oxygen atoms
is equal to zero
so let's replace o with negative two
two times negative two is negative four
and if we add four to both sides
pb is in the plus four oxidation state
so therefore to name it
it's going to be called
lead
for
oxide
try this one
let's see
v3
p5
and
sn
3
po4
four
so feel free to pause the video and try
those examples
so v is vanadium p is phosphorus but
p is going to be the phosphide ion so we
have vanadium phosphide but we got to
find the oxidation state
so let's write an equation 3v
plus 5p
is equal to 0.
now phosphorus as an ion has a negative
three charge
it's in group 5a of the periodic table
so 5 and negative 3 is negative 15.
so if we add 15 to both sides 3v is
equal to plus 15.
and then if we divide by three
vanadium is in the plus five oxidation
state
so to name it
it's going to be called
vanadium
5
phosphide
so let's try our last example
sn is 10 p.o force phosphate so let's
calculate the oxidation state
so we have 3sn
now you want to view phosphate as a
single unit because you know the overall
charge
so we have four phosphate units
and the net charge is zero
so phosphate as a polyatomic ion has a
net charge
of minus three
so four times negative three is negative
12. if we add 12 to both sides we get
this
and our last step is to divide by three
so therefore 12 divided by 3 is 4.
so 10
is in the plus 4 oxidation state
so now we can write the name
so it's going to be called
tin
for
phosphate
so now you know how to name ionic
compounds that contain transition metals
and even polyatomic ions
