00:00 So now that we've explored covalent bonds, the very strongest of biological bonds let's take a look at ionic bonds. Common table salt or sodium chloride is a result of a formation of ionic bonds. Ionic bonds result from first, creating an ion by stealing an electron from one and then the resulting charge of a positive and negative sticking together. So they are less strong than a covalent bond. That's still fairly stable. I think of this as an example of, say that having a full electron shell is like having all of the clothes on that you need, eight electrons. 00:41 And having not so full electron shell is sort of like that you would want to have another item of clothing on. Say I'd like to put my jacket on. So, in this case we have sodium which actually has one valence electron. It could easily drop that valence electrons they had and be very happy with a regular set of clothes. Or it could gain seven more electrons which is particularly difficult. 01:10 So in this case, it's actually more willing to give up one electron. So now, let's take a look at chlorine. It's the perfect pairing for sodium. It has seven valence electron and space to gain one. 01:28 Again, it wants to be fully clothed. So it's going to run on over to sodium. It's going to grab the extra electron on the outside and put in on itself. Now sodium is quite angry. And so sodium is going to run after chlorine and try to get its item of clothing back. Say its jacket. 01:49 Because sodium is chasing down chloride, they're going to stick together. So the positive charge of sodium and the negative charge of chlorine lends itself to them, sticking together and forming a crystalline structure. So when chlorine steals the electron from sodium, it satisfied the octet rule and also left sodium satisfied because it also has a full valence shell. Both of these molecules are now stable when they are in association. So when we stir our sodium chloride into a glass of water, the sodiums and the chlorides are literally falling apart because of the ionic charges. And shortly, we'll start to understand how water dissociates and polarity of different molecules such that sodium and chloride can actually become dissolved in water.
The lecture Ionic Bonds – How Atoms Come Together to Form a Molecule by Georgina Cornwall, PhD is from the course Introduction to Cell Biology.
Which of the following best describes ionic bond formation?
What happens to NaCl crystals upon dissolving in water?
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