Isotopes are different versions of the same element, distinguished by having the same number of protons but varying numbers of neutrons in their atomic nuclei.
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what are isotopes isotope is a word that
gets thrown around in chemistry a lot so
like what are they really quickly
Isotopes are different versions of an
element or different versions of a
certain kind of atom this can be a
tricky concept though and a lot of
people get confused by Isotopes so I
want to describe them by starting out
with an analogy to cars okay I want to
talk to you about the madeup car called
The Lamona
the epitome of luxury and it's known for
its very distinctive styling as you'll
see the lemona looks like a lemon now
the Lamona comes in three different
models there's the lemona G the Lamona
GX and the Lamona
gxl they're all different colors as you
can see but each of these models also
has unique features one has a radio and
leather seats the GX here has chrome
wheels and a CD player it's blue the red
gxl has massaging seats Platinum spinner
wheels and everything but here's the
point they are all Lonas they're all
Lonas because they all have this
distinctive styling they look like a
lemon and that's what makes a car a
lemona okay so it doesn't matter what
color it is and it doesn't matter the
various options that you get in these
models the G the GX or the gxl what matters
matters
is that they all have this particular
shape that's what makes a Lona a Lon so
we have these three different
models I want to use this analogy now to
talk about the same thing but with atoms
I want to now introduce you to three
models of carbon just the way they're
three models of Lon okay here are the
drawings of each one of them and what
we're particularly concerned about is
the nucleus I'm using these red dots to
symbolize protons and I'm using the blue
dots to symbolize neutrons the swirly
circles are supposed to represent
electrons that are buzzing around the
nucleus but we don't really want to
worry about that too much right now
anyway these three models of carbon are
carbon 12 carbon 13 and carbon 14 let's
look at the options in them like we did
with Alona let's look at how each one of
these different types of carbon differs
okay so if we count the number of
protons in carbon 12 we'll see that it
have six protons and if I count all the
blue spots here I have six neutrons okay
carbon 13 1 2 3 4 5 six red spots six
protons in this one I have seven
neutrons and in carbon 14 down here I
have six
protons and I have eight
neutrons so what do we have in common
here all the different models of the
Lona even though there are things that
they differed about all have the same
distinctive lemonlike shape so for
carbon what they all have in common is
they have six
protons six protons in the nucleus and
that's what makes a carbon atom a carbon
atom okay so it turns out that it
doesn't matter how many neutrons it has
six neutrons seven neutrons eight
neutrons no big deal it's just like
painting Lona different colors or adding
a radio or a CD player the neutrons it
doesn't matter it doesn't change the
fact that each one of these are a
carbon that's because carbon is defined
by the fact that it has six protons in
its nucleus if you look it up on the
periodic table you'll see something that
looks like this and the number up here
is the atomic number six which means
that if an atom has six protons it's
carbon okay so that's what these all are
they all isotopes of carbon they're
different versions of carbon or
different models of carbon with the same
number of protons and different number of
of
neutrons so look at how I wrote this got
carbon 12 carbon 13 carbon 14 up here I
want to take a minute and talk about the
numbers so the number of protons in the
nucleus we call that the atomic
number you may already know that and
then carbon 12 this 12 that I've written
here refers to to a different number and
we call that the mass number the mass
number as you'll see is the number of
protons plus the number of neutrons so
this is carbon 12 6 + 7 protons and
neutrons is 13 here 6 Plus 8 is carbon
14 here so that's how we distinguish
between these different isotopes
different types of carbon there's
another way that we sometimes indicate
these different isotopes of an atom
instead of doing 12 and 1 or 14 and
that's by using something called isotope
notation let me show you how we do that
the way we write carbon 12 or 13 or 14
and isotope notation is we start out
with a chemical symbol if you don't
already know that you can find it on the
periodic table so here it is it's a big
upper case C
C
so I start with my C for carbon and then
on the lower corner here I write the
atomic number so that's going to be six
and then up top I write the mass number
which is 12 so this is carbon 12 written
in isotope notation carbon 13 is going
to be 6 again because all carbon has six
protons in its nucleus but then the 13
up here and finally carbon 14 written in
isotope notation is
c614 so that's how we can write all
these isotopes of carbon in isotope
notation and of course you can also
write it as just the element name with a
dash and then the number so carbon isn't
the only type of element that has
multiple Isotopes in fact just like cars
almost every form of element comes in multiple
multiple
Isotopes here are the calcium Isotopes
for example if you look up on the
periodic table you'll see that calcium
has an atomic number of 20 which means
that any atom that has 20 protons in its
nucleus is calcium but just like with
carbon you can vary the number of
neutrons that are in the nucleus you get
all these different isotopes but you
still have calcium calcium we got 40 42
43 44 46 48 all of them have 20 protons
in the nucleus but they have varying
numbers of neutrons just like we did
with carbon we can write all of these
calcium Isotopes in isotope notation
where we have the mass number here up at
the top and the atomic number down at
the bottom you'll see they all have the
same atomic number of 20 but different
Mass numbers the sum of protons and
neutrons the same is true for iron just
to give you another example iron has 26
protons in its nucleus an atomic number
of 26 and there are four known isotopes
of iron all of which have 26 protons in
the nucleus but they all have varying
numbers of neutrons you add these
together to get the mass number and then
you can write it in isotope notation
with a mass number up here and the
atomic number down here so just to
review what we've talked about atoms
come in different versions known as
Isotopes these are like the different
versions of a car or something the
number of neutrons change but just as
long as you have the same number of
protons you still have the same type of
atom the same type of element you can
take uh an atom and write it in isotope
notation where you put the atomic number
on the bottom and the mass number up
here so that is uh that's what Isotopes are
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