Write Lewis structures for each molecule or ion. Use expanded
oc...

Question

Write Lewis structures for each molecule or ion. Use expanded 
octets as necessary. 
b. AsF6-

Accepted Answer

Hello everyone today. We are being asked to draw a lewis dot structure for the sulfate and ion S. 042 minus. And the first thing we want to do is you want to take into account how much of each atom that we have. So we have one sulfur and four oxygen's sulfur is in the sixth group of the periodic table and therefore has six valence electrons. Giving us six electrons from their oxygen is also in the sixth group and it has six valence electrons giving us 24 electrons here. And so we have 30 electrons from these two atoms. But notice this negative two charge here. This denotes that we have an excess of electrons. And to in fact, so we're going to go ahead and add two electrons here for a total of electrons. The second thing we must do is identify the least electro negative atom because that adam is going to be the one that goes in the center according to the periodic table. The electrode negative activity of an atom increases as we go up the periodic table and to the right and so with that sulfur is going to be the least electro negative and that will go in the center here and we're going to connect that with the four oxygen atoms here. Notice how we used four bond lines. Each bond line represents two electrons. So we have eight. So we've already used eight electrons up. So we go from 32 to 24 electrons remaining. The next thing I wanna do is you want to fulfill the octet rule around each atom on the outside and then work on the center atom with that oxygen has six valence electrons. And it also needs an octet rule fulfillment of eight electrons around it. And so if we were to put six electrons here that gives oxygen seven valence electrons, which is incorrect. So we must do we must add to bond lines between oxygen and sulfur and leave the other two sulfur oxygen bonds as single bonds. And we'll see why in a bit. So we've already just we've just added two additional bond lines. So that's four electrons. So we're left with 20 and now we can start adding our electrons around. So to fulfill the octet rule For the oxygen at the top, we're going to add four electrons. We're gonna do the same thing with the oxygen on the bottom. That gives us eight electrons gone. And we have 12 remaining. And to fulfill the octet rolling oxygen on the right, we have to add six electrons around each oxygen here. So why is this example of this oxygen with six with six electrons around it needed or acceptable. It's because this ion has a negative two charge. And so we have to have two negative charges on this compound somehow. And so that's how we're going to do it. We have used all of our electrons in this example here. And this is our lewis dot structure for the sulfate and ion, we also have to take into account that negative two charge. So before we completely call this done, we must add that negative two charge outside of the brackets there. And now we have completed it. I hope this helped until next time.

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