Alright, so now that we know as that what ions are, they are charged, atoms or molecules. And the two types, of course, you can either have positive ions or negative ions. Now ions, especially when we're talking about atoms, are formed by the loss or gaining of electrons. We're never going to form a positive ion by losing a proton from the nucleus, or excuse me, gaining a proton in the nucleus. Or we're never going to form a negative ion by losing a proton in the nucleus. That's of course a nuclear, a coag-nuclear chemistry. And for ions, we're talking about chemical reactions, which are only going to involve electrons. Okay, so of course if you're a positive ion, that means you lost one or more electron. Say for, so for instance the, well just to start off, it turns out that metal atoms tend to lose electrons. So for instance sodium, the sodium that we need in our diet, it's not the sodium atom, the neutral atom, that's very reactive metal. What we need is the sodium ion. And so it will lose an electron to form that. So sodium neutral atom loses one electron and forms the sodium cation. And of course we always show the charge on the top right superscript. Okay, if it's just a plus one charge, you really don't have to show the number one, you can just use a plus. Atoms can lose more than one electron, such as magnesium. Atmuseum usually use it loses two electrons to form a two plus, positively charged ion. A positively charged ion is called a cation. This stands from the electrochemistry, in which an electrochemical cell, they're attracted to the cathode. But a positively charged ion is called a cation. Negative ions, on the other hand, are formed by gaining electrons. Gain at least one electron. It turns out that due to electron activities that non-metals tend to gain electrons. And so the good example for that would be sort of the most common counterpart to sodium. And sodium, and that is chloride. Chlorine atom gains one electron to form the chloride ion, Cl minus ion. Oxygen when it reacts with metals, it likes to gain two electrons to form the oxide ion with a two negative charge. And again, we don't have to write the one for a negative one charge, but anything higher you do have to write the number. These, in contrast to the cations, negatively charged ions are called anions. And just as I said, without really going over it, the anions of elements have their name chain. If we look on a periodic table of the elements, chlorine, CL is called chlorine. And of course when it's in a ion of compound as an ion, we call it chloride. So the name changes to IDE, the stem of the name changes to IDE. We're going to turn the stem of the name into IDE. So we said that was chloride, oxygen, when it gains two electrons to form the anion, it is the oxide ion. Notice that we didn't have to change the name for the metal cations. They do not undergo a name change. This is sodium atom. This is sodium cation, both sodium in both cases. Magnesium atom, magnesium cation, with a plus two charge. Now, in both of these scenarios, for the positive examples, for positive and negative ions, I said the sodium tends to or likes to form a sodium plus one ion. And really, the truth is that it will always form a plus one ion. Magnesium will always form a plus two ion. Chloride, always a negative one ion. In oxygen, when it forms just the elemental ion, always a negative two. And that has something to do with called the octet bowl. If we go back to a periodic table of the elements, and if we remember our discussion of valence electrons, the number of electrons in the outer most shell or highest energy level, we could use the A numbering system to determine how many valence electrons a particular atom has. So for instance, the alkali metals in hydrogen and group 1A have one valence electron, boron aluminum in group 3A have three valence electrons, oxygen, and the rest of the elements in group 6A have six valence electrons. And then with the exception of helium, the elements in group 18 or 8A have eight valence electrons. And if you remember our brief discussion of the noble gases, the noble gases in group 18 or 8A, we said that they are very unreactive. That is because they are very stable. They don't want to gain or lose electrons or share valence electrons with other atoms. They are very stable. And so what tends to happen with elements is that elements will react in a way to get the same number of valence electrons as their sort of nearest noble gas element. And so since neon argon cryptons, even radon have eight valence electrons, there is a very strong possibility that the elements will react in a way to get to those eight valence electrons. And that is what is known as the octet rule. Elements will react in a way. To get or achieve 8 valence electrons. We also call this a subset to the octet rule, which I usually like to call the duet rule, is a very small element like hydrogen, lithium, and brilium, or we will be stable with an electron configuration just like helium. And so they will tend to react so that they get to two valence electrons just like helium.