What are Isotopes?
what
areisotopes
isotope is a word that gets thrown around in chemistry a lot so likewhat
are they really quicklyisotopes
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 byisotopes
so I want to describe them but starting out with an analogy to cars okay I want to talk to you about the made up car called the lemona 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 lemona comes in three different models there's the loaner G the Lamone of GX and the lemona GX l 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 g XL has massaging seats platinum spinner wheels and everything but here's the point they are all lemonis they're all the moniz because they all have this distinctive styling they look like a lemon and that'swhat
makes a car ala Moana okay so it doesn't matterwhat
color it is and it doesn't matter the various options that you get in these models that you get the GX or the GXLwhat
matters is that they all have this particular shape that'swhat
makes Ala Moana alimony so we have these three different models I want to use this analogy now to talk about the same thing but with ABS I want to now introduce you to...
three models of Kart just the way there are three models at the moment 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 that swirly circles are supposed to represent electrons that are buzzing around the nucleus but we don't really want to work about that too much right 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 Ala Moana 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 have six protons and if I count all the blue spots here I have six neutrons okay carbon 13 one two three four five six red spots six protons in this one I have seven neutrons and carbon-14 down here I have six protons and I have eight neutrons sowhat
do we have in common here all the different models of the lemona even though there are things that they differed about all have the same distinctive lemon like shape so for carbonwhat
they all have in common is they have six protons six protons in the nucleus and that'swhat
makes a carbon atom a carbonyl 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 lavona 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 carbonate 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 looks like this and the number up here is the atomic number six which means that if an atom has six protons its carbon okay so that's
what
these all are they're allisotopes
of carbon they're different versions of carbon or different models of carbon with the same number protons in different number of neutrons so look at how I wrote this got carbon-12 carbon-13 carbon-14 up here I want to take a minute talk about the numbers so the number of protons in the nucleus we call that the atomic number you may already have it and then carbon-12 this 12 that I've written here refers 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 plus 7 protons and neutrons of 13 here 6 plus 8 is carbon 14 here so that's how we distinguish between these differentisotopes
different types of carbon there's another way that we sometimes indicate these differentisotopes
of an atom instead of doing 12 and 13 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 isotope notation is we start out with a chemical symbol if you...
don't already know that you can find on the periodic table so here it is it's a big uppercase C so let's start with my C for carbon and then on the lower corner here I write the atomic number so that's going to be 6 and then up top I'll 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 6 protons since nucleus then the 13 up here and finally carbon 14 written in isotope notation to c6 14 so that's how we can write all these
isotopes
of carbon in isotope notation then 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 multipleisotopes
in fact just like cars almost every form of element comes in multipleisotopes
here the calciumisotopes
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 the nucleus you get all these differentisotopes
but you still have calcium calcium we've 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 calciumisotopes
in isotope notation where we have the mass number here up at the top and then 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
