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Hi there.
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In this question, we are looking at some lewis electron dot structures.
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And for a structure to be correct, two things need to be satisfied.
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It needs to have the correct number of valence electrons, which are represented in dot structures as dots.
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And each atom needs an octet, with some atoms having an expanded octet, meaning it could have more than eight for certain atoms.
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All right, so let's look at what we have here.
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Our first one is for sf4.
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And to tell if these structures are correct, one of the things we need to do is determine how many valence electrons we have to work with.
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Sulfur is in group six of the periodic table, so it has six valence electrons.
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Each flooring, being a halogen in group seven, each flooring has seven.
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And there are four fluorins, so four times seven is 28.
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Add that to six, we get a total of 34 valence electrons.
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Okay, so that brings us to the structure that they give us.
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They give us sulfur with four bonds.
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That's two, four, six, eight electrons, and then another pair on the sulfur for 10.
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This fluorine has six more, so that's 16.
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This fluorine has six more.
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That's 22, 28, 29, 30, 31, 32, 33, and 34.
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So we have the correct number of dots, and each element has an octet except for the sulfur.
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And sulfur can have more than an octet.
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It can have what's called an expanded octet.
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We said it has 10 electrons around it.
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Therefore, this is a reasonable structure.
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It would be wrong if we put more than 8 around flooring, because flooring cannot have more than an octet.
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Because it does not have any de -orbital to stick some extra electrons in.
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But sulfur can.
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All right.
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So that one is correct.
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Let's look at the next one.
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The next one, we have c -l -o -3 with a negative charge.
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It's a polyatomic ion.
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So chlorine is a halogen.
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It's in group 7a.
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It has seven electrons.
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Each oxygen is in group 6a.
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So each of those has six.
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And then we have to add one electron for that unit of negative charge.
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So we have 7 plus 18, is 25 plus 1 gives us 26.
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So we need 26 valence electrons or 26 dots...