 Okay. Neutrons are neutrally charged particles, so they have no charge at all, and they're also found in the nucleus. So I tried to color code this to show you, oh look, how many neutrons do I have in this atom here? There's three neutrons in this particular atom. Neutrons contribute to the stability of an atom. So an unstable atom will literally fly apart, and a ton of research is done on unstable atoms. They're actually really interesting. Sometimes when they fly apart, they emit light. Sometimes when they fly apart, they like then combine and release a lot of energy. Like there's all sorts of bizarre things that happen with particles. And then, oh, focus. It's really interesting, but because the number of protons determines our element, the number of neutrons has nothing to do with what element we're in. In a study of life, the chemistry of life, carbon is probably one of the most important elements. So let's just consider a carbon atom. And my symbol for carbon is of course C. So I don't know if you have a periodic chart to consult, but if you do consult your periodic chart, you will see that, okay, a carbon atom has six protons, six positively charged particles in the nucleus. And I'm going to tell you right now that you have different flavors of carbon atoms. Dude, you can have carbon atoms that have six neutrons. Let's do an N, maybe we'll go like that for neutron. Or you can have eight neutrons. You can actually probably have any number of neutrons in the nucleus of a carbon atom, but again, they contribute to the stability of the atom. And so there are usually a couple forms of the atom that are more stable than others. In fact, this atom that has six neutrons, a carbon atom with six neutrons, is much more stable than a carbon atom with eight neutrons. Now, of course, elements that have different numbers of neutrons like a carbon atom that has six neutrons versus eight neutrons, those are called isotopes of each other, isotopes of carbon, isotopes. Isotopes have different numbers of neutrons. And you're probably going, dude, really? Whoa, because, but I'm going to give you something that probably you are familiar with. Most carbon atoms have six neutrons and six neutrons and six protons with six plus six. That's 12. Most carbon atoms come in the carbon-12 flavor, okay? This is the most common and the most stable. But guess what? You can have, tell me, what isotope has eight neutrons? Carbon-14 is less stable and it has eight neutrons. Now, here's the really cool thing. Isotopes, those are both different isotopes of carbon. And isotopes can decay, what? So the less stable form of carbon can decay and turn into the more stable form. And if you think about that, like, dude, what has to happen in order for carbon-14 to decay will make sense that we would actually have to lose a couple of neutrons. And since it is less stable, it can. It can lose particles and turn into a different isotope. And you can have decay that is actually releasing radiation and that's radioactive decay. You can have decay that releases light that you can actually literally see. These are light-emitting isotopes. Are you extremely useful for things like focus, things like, oh, what's that called, medical imaging? Like when they do this, like PET scans or CT scans where they actually go in and they give you this radioactive substance that you drink, radioactive glucose, that's what they do. In fact, oh my gosh, I've got this totally. I want to show you this. This is a glucose molecule. Awesome. So they take glucose and then they attach an unstable isotope of fluorine, which is another atom. Instead of having, look, here normally they have an oxygen attached at this point. So then they're like, dude, we're going to make this glucose, this is a glucose molecule, glow-in-the-dark. And so they attach this radioactive fluorine atom to the glucose molecule and that it's an isotope, it's fluorine-18, and since it's an isotope, it actually, it's not the most stable one and it decays. And when it decays, it gives off light. So now think about this. You have a light-emitting particle of sugar, glucose. And you can actually do things like give somebody a cup full of radioactive glucose water and they drink it and then all their body parts that use a lot of glucose, that yumpsualize glucose like mad, like active brain parts or horribly cancer tumors, they'll glow in the dark. And there's a special imaging tool that can take a picture and capture the light. They use this tool in things like brain research. So check out this little image of a brain here. This is your brain on radioactive glucose when it's doing a task that it's never practiced before. And this is your brain doing the same task after you have experience doing it. So this might be, you know, playing Mary Had a Little Lamb on the piano when you are just learning the piano. And then after you're like, dude, I can play Mary Had a Little Lamb in my sleep, then you play Mary Had a Little Lamb and a different part of your brain is active. How do they know that it's active? Because it's using the glucose. And the more glucose it's using means that's actually like doing something there. This part of your brain, when you're learning something new, is like, it's not even on the screen. It's not using a lot of glucose to do the task. Cancer is a very metabolically active thing. And it's just your cells that have like gone crazy and are more active than they should be. They're reproducing more than they should. And they're just, oh my gosh, yumps sterilizing as much sugar as they can come in contact with. So a tool like this will tell you if you end up with a glowing spot and you're not practicing, you know, they're not checking out your brain to see, you know, doing neurobiology experiments on your brain and you had a glowing spot like this, they'd be like, whoa, that's not normal. Why is that part of your brain using up more glucose? Because remember that glucose was like glow in the dark. Because why was it glow in the dark? Because it had this radioactive fluoride ion attached to it. So if you've got that little radioactive thing that's emitting light, you can actually use that for research. Neutrons are actually really cool. Neutrons do not change the element. Changing the neutrons gives you different isotopes. Awesome. Okay, last particle that we have to look at are the electrons. Again, another very significant piece of our atomic puzzle.