So now that we've talked about ions, in this video we're going to talk about ionic bonds. And so ionic bonds are pretty much exactly what they sound like, they are bonds that form between ions. More specifically, we can define ionic bonds as electrical attractions between oppositely charged ions, between cations and anions. Notice that "ionic bonds" does not have the word "covalent" in it. Recall from our previous lesson videos, the word covalent means sharing of electrons. But because ionic bonds do not have "covalent," ionic bonds involve no sharing of electrons. Instead, ionic bonds are characterized by a complete transfer of electrons. This complete transfer of electrons can fill the valence shells of both atoms involved in the transfer. Because electrons are negatively charged, by transferring these negatively charged electrons, it can create new charges and therefore create ions. And then, those ions that are created can form an ionic bond. Let's take a look at our example down below at the formation of the ionic bond in sodium chloride or NaCl.

Notice over here on the left-hand side, we're showing you a sodium atom and a chloride atom. Chloride is much more electronegative than sodium, which means that chloride pulls on electrons a lot harder than sodium does. The discrepancy in electronegativity between these two atoms is so large that they don't even share electrons at all. Instead, chlorine is so much more electronegative than sodium that it's going to steal this electron, and it's going to be completely transferred from the sodium to the chloride atom. Notice that the sodium has only one electron in its valence shell, highlighted here in pink, the one that's furthest away from the nucleus. If it loses this electron, then its valence shell will become full. Notice that the chloride atom is missing just one electron to have a full valence shell. It's in the interest of both atoms to undergo this transfer of electrons so that they both end up with full valence shells. Here we're showing you the electron transfer from sodium to chloride. Ultimately, the sodium atom gains a full octet, and the chloride also has a full octet after the transfer. Another thing to note is that the sodium atom becomes a sodium ion because it gains a charge, and the chloride atom becomes a chloride ion because it gains a charge. Because the chloride is gaining a negatively charged electron, it gains a negative charge. Here in this little dotted box, we can put a negative charge to remind us that the chloride ion is going to have a negative charge. The sodium ion, which is giving up a negatively charged electron, is going to become more positive in the process, so it gains a positive charge. There is a natural attraction between positively charged cations and negatively charged anions. This interaction, forming between these two ions due to this attraction, is what we call the ionic bond.

After the transfer of electrons, we have completely filled valence shells and have created these positive and negative charges, just as we indicated above. Also, note that down below, when you have the sodium ion and the chloride ion, they are forming this ionic bond between the two ions, together the sodium and chloride ions form a sodium chloride molecule. This sodium chloride molecule is really what makes up your regular everyday table salt that you might have in your kitchen right now. So, that's something important to also keep in mind. This concludes our introduction to ionic bonds, and we'll be able to get some practice applying these concepts that we've learned in our next few videos. I'll see you guys there.