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 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 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 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 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