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Hi there.
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In this question, we are asked, first of all, to write a couple of electron configurations following alphau's rule for filling orbitals from the lowest energy level on upward.
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So in letter a, we want to write the electron configuration for silicon.
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And as we look at the periodic table, we see that silicon is right here.
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It is atomic number 14.
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So that means it has 14 protons, but more importantly for us, for this question, it has 14 electrons.
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Because since it's a neutral atom, it would have the same number of negative charges as positive charges.
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So let's go ahead and put those 14 electrons into their orbitals.
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We always have to start with 1s because 1s has the lowest energy.
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And it can hold two electrons.
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So 1s2.
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Next comes 2s.
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Again, it's an s orbital, so it can hold a maximum of two electrons.
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After 2s comes 2p.
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There are 3 p orbitals.
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They can each hold two electrons for a total of 6.
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Then we get to 3s.
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Again, it's an s.
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It can hold 2.
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And if we count we're up to 12, what comes next is 3p, but it must be 3p 2.
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All right.
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These are the 14 electrons of silicon.
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Of course, when you're inputting your answer, make sure you follow the whole.
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Instruction there for using those carrots.
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Okay, for letter b, we want the complete electron configuration for gallium.
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All right, so now we're going down here to gallium.
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Its atomic number is 31.
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So we're going to start out the same way, but we just need to keep going now until we get to 31.
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So 1s2, 2 .2, 2p6, 3s2.
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This time the 3p, 3p, this time the 3p, is going to be filled up because we need to keep going.
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After 3p6, in order of energy, the next one is 4s.
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We put two electrons in that.
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Then after, oops, i forgot one here.
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After 4s, then we fill the 3d.
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3d holds 10.
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And then finally, 4p1.
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This gives us a total of 31 electrons.
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Okay, and again, we're just following the alphbaugh order.
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And putting electrons in orbitals until we get up to the number that we meet.
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Okay, for our last question now, though, we are going to use the periodic table to determine what configuration or what the last sub -level is, the last occupied sub -level for each of the given elements.
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So we can use the periodic table for that.
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The energy levels are represented by the periods.
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So 1, 2, 3, 4, 5, 6, and 7.
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We have to remember that the ds are one energy level behind.
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So 3, 4, 5, and 6.
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And the f are two energy levels behind.
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So they're only filling 4f and 5f.
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Okay, for our next one then.
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For our next one, we need to talk about the block...