 Hey everybody, Dr. O here. Let's talk about the periodic table of the elements. So the periodic table is a chart that has all 92 elements that are found in nature plus a bunch of other elements that have been discovered experimentally. The elements are in order by their mass, their atomic number, which is the number of protons. That's how they've been organized. Now, other people tried to develop periodic tables that were organized in different manners, but this is a perfect way to do it and I'll explain why in just a moment. Here we see the basic structure of the periodic table. It is designed to group similar atoms together. It does a very, very good job of that. On the left-hand side, you see group one there. That's going to be the alkali metals. Group two is called the alkaline earth metals. They're in the middle. You have the transition metals. Then you go near the other end. I generally don't talk about the nictogens or chalcogens much, but the nictogens would be also known as the nitrogen family and the chalcogens are the oxygen family. The halogens and what I call group 7a, they're all going to be bundled together there. Then we have your inert noble gases on the far right in what I call group 8a. Then they have lanthanides and actinides there on the bottom. But in human anatomy and physiology, we generally care about the first 20 elements to calcium and then just a handful of other ones. So we certainly won't be spending any time there at the bottom of the periodic table. So how they're organized. There's two ways to look at it. The periodic table is organized in periods, which are horizontal. They don't have a whole lot of value. The value is in the groups. Now, they're vertical. The other name for groups is families. And I like that because you are more like your family for better or worse than anyone else on the planet. So these groups or families are how we bundle atoms together and then they behave like the other elements that are in that group. Let me give you just a few examples. So here on the right, we see bromine and iodine. They're very similar. They affect absorption of one another. So if you have a lot of bromine in your diet, that can actually decrease iodine absorption and lead to some health problems potentially. Carbon, we call carbon, we're carbon-based life forms. We think carbon is critically important for life. I've heard scientists say that if carbon didn't exist, we would have had to create it. But if you were to ask me or anyone else, what is another element that life could be built on, it'd be silicone. And you see how it's right by there. Just like bromine and iodine very close together in the same group, very similar, carbon and silicone, same way. Over on the left hand side, sodium and potassium there. Sodium chloride is table salt. Potassium chloride is Mrs. Dash. It's a salt alternative because they have very similar properties. Another one, you see calcium and magnesium very close together. Their absorption is linked together. So a lot of calcium could decrease absorption of magnesium and vice versa. But magnesium and calcium since they are so similar, having a diet high in magnesium can actually spare some calcium and decrease your calcium needs. So there's examples of how every element is basically more similar to other elements in its group and especially ones right near it than anything else on the periodic table. That's why these groups or families are so critically important. Here's why. You see all these charges on here. They're organized by how many electrons they want to gain, lose or share in order to be happy. So on the far right, we have the noble, the inner noble gases. They're already stable, already happy. They don't want to react. They don't want to give up electrons. They're already perfectly fine. We see on the far left side that group 1A, all of them have a plus one charge mean they want to get rid of one electron. Group 2A, two plus charge because they want to get rid of two electrons. Over on the far right, we see the halogens there. They have a minus one charge because they only want to gain one electron. So that's why organizing them in groups is so critically important because they have very similar behaviors. Now it gets messy there in the middle a little bit but we won't dive too deep into that. Here we see how to read the periodic table. So you see an example here of carbon. The C is its chemical symbol. Obviously some of those are very, very important. Then you have the atomic number. So the atomic number is the number of protons. And that's the most important number because that's what determines what element this is. The bottom number there you see is the mass number. Notice that there's both carbon 12 and carbon 13 and there's even a radioactive isotope called carbon 14. So the mass number is the number of protons plus neutrons. So carbon 12 here must have, we know it has six protons because it's carbon. So it must have six neutrons. Carbon 13 has six protons and seven neutrons. But normally the number of protons and neutrons and electrons are the same. But if you change them, here's what happens. Very, very important. If you change the number of electrons in an element, it will become an ion. If it gained the negative electron, it will become a negative ion called an anion. If it loses a negative electron, it will become a positive ion called a cation. If you gain or lose a number, if you change the number of neutrons, we now have an isotope that was covered in a separate video. If you change the number of protons, though we have a new element. You cannot change the number of protons to carbon or it's no longer carbon. If you added two protons to carbon, it's not some special form of carbon, it's now oxygen. All right, so that's the atomic number and the mass number. Now the actual atomic weight of these is not gonna be whole numbers. There are gonna be some variation. It just has to do with how they actually weigh individual subatomic particles and the fact that you have isotopes. Not all carbon is carbon 12, for example. All right, just give me a couple more examples. You don't see them on the screen here, but hydrogen's unique because hydrogen is the only element that doesn't have a neutron. So hydrogen is made of a proton and electron. That's why if you remove an electron from hydrogen, it's now called a hydrogen ion, but it also can just be called a proton. So you hear terms like proton pump or proton donor in the future. A hydrogen ion and a proton are the same thing because hydrogen didn't have a neutron to begin with. But on the flip side, you see uranium. Uranium is a heavy metal. It's gonna have a mass number of 238. It only has 92 protons, but it has 146 neutrons typically. So if you look at its mass number, it would be 238. That's gonna be one of the heaviest elements that we would ever talk about in this class. All right, so that is the periodic table of the elements and what I think you need to know to move forward. I hope this helps. Have a wonderful day. Be blessed.