2. Chemistry
Ionic Bonding
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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. Now notice that ionic bonds does not have the word covalent in it. And recall from our previous lesson videos, the word covalent means sharing of electrons. But because ionic bonds does not have covalent, ionic bonds have no sharing of electrons. Instead, ionic bonds are characterized by a complete transfer of electrons. Now this complete transfer of electrons can fill the valence shells of both atoms involved in the transfer. And 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. So let's take a look at our example down below at the formation of the ionic bond in sodium chloride or NaCl. And so notice over here on the left hand side we're showing you a sodium atom and a chloride atom over here. Now Chloride is much, much more electronegative than sodium, and what that means is that chloride pulls on electrons a lot harder than sodium does. In fact, 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. And so, what you'll notice is that the sodium has only one electron in its valence shell, and notice that the valence shell is the one that is highlighted here in pink, it's the one that's furthest away from the nucleus. Once again it only has one electron in its shell, so if it loses this electron then its its valence shell it's gonna be become this one and it will be a full valence shell. And notice that over here the chloride atom is missing just one electron in order to have a full valence shell, And so it's actually in the interest of both atoms for them to, undergo this transfer of electrons so that they both end up with these, they both can fill their valence shells. And so here what we're showing you is the electron transfer, from sodium to chloride. And so ultimately what that means is the sodium atom, once again, it's going to have a new valence shell that is full, it gains a full octet. And the chloride, is going to also have a full octet after the transfer. Now another thing to note is that the sodium atom becomes a sodium ion when the transfer is over. It gains a charge, and the chloride atom becomes a chloride ion once again because it also gains a charge. Because the chloride is gaining a negatively charged electron, it's going to gain a negative charge. And So here in this little dotted box we can put a negative charge to remind us that the chloride ion is gonna have a negative charge. And of course this 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. And so there is a natural attraction between positively charged cations and negatively charged anions. And so this interaction that we see right here forming between these 2 ions due to this attraction is what we call the ionic bond. And so what you can see is that, after the transfer of electrons that, the we have completely filled valence shells and we have, created these charges, these positive and negative charges, just as we indicated up above. We fill the valence shells of both atoms and we create charges. And then also notice that down below, when you have the sodium ion and the chloride ion and they are forming this ionic bond between the 2 ions, together the sodium and the chloride ions form a sodium chloride molecule and so it can still be a molecule by forming ionic bonds. And so, one thing to also note is that the sodium chloride molecule that you see right here is really what makes up your regular everyday table salt that you might have in your kitchen right now. And so, that's something important to also keep in mind. And so this here 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. So I'll see you guys there.
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