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okay so let's talk about our actual
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electron configurations I'm going to
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draw a really simple one for you
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one of the simplest ones that we could
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do and then we're going to talk about
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the three rules that go along with that
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and then we're going to do slightly more
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complicated ones as examples later on in
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the next video so that you can see how
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those rules are actually going to play
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out in a bigger setting so we're going
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to start with one that's relatively
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simple and again you need to have your
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periodic table out because obviously
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I've miniaturized mine and I don't have
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the whole thing here so we're to start
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with nitrogen okay and if we went out
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and we found our little chart for
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nitrogen we would see that nitrogen had
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an atomic number of seven and it's got a
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it's got a molar mass sorry an atomic
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weight of something like fourteen point
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oh one or fourteen point zero one or
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something like that so seven is what's
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important to us because that's the
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number of electrons that we have
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remember that seven is actually the
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number of protons but in a neutral atom
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it's going to have an equal number of
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electrons to balance it out and so I'm
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going to draw my electron configuration
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for nitrogen and then I'm going to use
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the model that I've drawn here to
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explain the rules to you the way that
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we're drawing this is what would be
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alternatively called either longhand
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electron configurations are oftentimes
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you would hear it called orbital
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notation instead of longhand electron
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configuration so what these little boxes
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are here and sometimes you'll see them
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drawn if you'll see them drawn in a book
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a textbook or something like that
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they would actually be drawn out as
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little boxes like that
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that's not really practical for us when
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you're writing a whole lot of them so
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usually we're just going to draw dashed
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lines each one of those lines represents
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an orbital okay and remember an orbital
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is a region in space where we have a
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good probability of finding a given
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electron and so I know that I have seven
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electrons here and so I'm gonna put my
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seven electrons in in such a fashion to
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draw the correct orbital notation of our
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nitrogen so all the pink arrows there
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are electrons and you'll see that I have
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seven of them and I've sort of a rain
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them in a certain way and I sort of
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started to draw the path in a certain
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way and so I'm gonna give you the rules
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that I used to do that and then in the
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next video we'll work a couple more
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examples so you can see a little bit
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more about how to draw them out in this
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way and by the way we don't usually draw
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them out in this way you'll see them a
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couple of times this way but most of the
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time we draw them in a much more
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condensed fashion and we'll get to that
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probably in our third video here so what
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are the rules that we're gonna use for
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this will rule number one it's called
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the Alpha Belle principle okay the Alpha
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Belle principle there's always these
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really important complicated scientific
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definitions for them and I'll pop those
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up in the video for you but what the
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alto principle really says and when it
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boils down to like simple and the
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liminal person speak is start at the
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bottom okay remember that if we were
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drawing this in some sort of like Bohr
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model structure here that this would be
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energy level one and this would be
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energy level two and there's a nucleus
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here and so you're gonna you want to
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start filling your electrons closest to
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the nucleus the lowest energy electrons
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are gonna be closest to the nucleus and
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what the Alpha Bal principle then tells
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us is start from the bottom so when I
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started putting my electrons in here I
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started at the 1s I went to 2s and then
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I went to 2p and then I would go to 3s
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and 3p and so on and so forth like we'll
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do in the next part of the video so the
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Alpha Bell principle says start at the
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bottom and again I'll pop up the more
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complicated definition for you but
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really that's that's essentially what it
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comes down to them you know it says hey
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you want to be you want to start at the
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lowest energy levels and go to the
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higher ones for us it means start at the
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bottom what that also means is that when
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you're drawing these out and this is
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gonna be tough for some of you don't
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start with 1s at the top and go that way
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start with 1s at the bottom and go the
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other way that just tends to be the way
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they're drawing sometimes an alternative
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method would also be that we could have
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drawn them out and said 1s 2s we would
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have drawn them in a straight line left
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to right because that's the way we would
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normally read things and that way can be
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useful that's actually pretty close to
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what we're gonna do in shorthand here in
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a little bit but this is traditional
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orbital notation because this sort of
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really lets you know that this is lowest
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next lowest highest energy level for
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this particular atom and that's
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important
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okay so rule number two is the Pauli
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exclusion principle that sounds really
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complicated the actual like one again
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the complicated scientific definition of
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it is a lot more complicated basically
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the Pauli exclusion principle says hey
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every electron has a unique set of four
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quantum numbers and no two electrons in
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the same atom can have the same four
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quantum numbers and what that would mean
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is that there always has to be a spin to
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them and you're like whoa what what does
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all that mean it doesn't really matter
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that much for us at the moment what that
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means for us in terms of actually
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writing our electron configurations
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again the easy speaker the normal person
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speak would be the Pauli exclusion
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principle tells us that you can only fit
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two electrons in an orbital and that
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when you put two electrons in the
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orbital the first one always goes up and
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the second one always goes down that
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means that they can't have the same spin
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electrons are spinning and so we're
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saying this way that one's spinning this
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way the other one's spinning the other
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way okay and again we're not getting in
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at all the quantum mechanics of that but
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that's essentially what the Pauli
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exclusion principle tells us at our
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level that we're worried about which is
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I can only fit two electrons in each of
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the orbitals that I'm gonna set up okay
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so that's rule number two rule number
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three is hummed rule and what hund's
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rule tells us is that if we have
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orbitals that are on the same energy
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level so remember that I said that alpha
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principle says that we start at the
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bottom lowest energy so 1s is at an
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energy level and then 2's is at a
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different energy level and 2p is higher
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than that but within 2p we have three
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orbitals okay that are all at the exact
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same energy level okay
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those have a specific name we call those
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degenerate orbitals meaning that they're
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all orbitals at the same energy and what
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hund's rule says is that if you're
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putting electrons into degenerate
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orbitals that what would be most
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favorable is that if you maximize the
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number of electrons with the same spin
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and you're like again what what does
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that mean that's sort of the more
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complicated
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definition what hugs rule really says
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for us is that when you're putting
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electrons into degenerate or the same
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level boxes that you put one in each
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before you go back and put the second
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electron in any of the boxes so the plot
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exclusion principle tells me I can't put
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more than two in a box but hund's rule
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tells me that sometimes I put one in
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each box before I then go back and put
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the second one in so this is a nitrogen
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if we were if we had an oxygen let me
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write that up there this is nitrogen if
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we had an oxygen say and I had an eighth
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electron remember oxygen is the next
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element over from nitrogen we had an
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eighth electron then I would go back in
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and I would have done my huns role and
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then I would come back and fill in my
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eighth electron there and then fluorine
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would be nine and neon would be ten and
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so on and so forth okay so one more
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quick thing because you might have been
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saying okay that's great I understand
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what you're saying about degenerate
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orbitals being those in the same level
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why does s have one and P has three how
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many did D and F have so real quick just
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let me tell you what each of those
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things are just to make sure that
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everybody is okay with that so they work
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like this s P D F okay s always has one
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orbital P always has three D always has
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five guess what s f has seven if we went
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to a G or an H which again are
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theoretically possible and then we would
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have nine and 11 and so on and so forth
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and again there's a quantum number
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reason behind that that does it that is
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really deeper than we need to go right
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now but what's important to us is this
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tells us how many boxes each of these
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get now here's the beauty of this you
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could memorize this and that will work
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just fine but the periodic table itself
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actually leads you to all of that stuff
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if you look at the periodic table and
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what I said was the s-block before there
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are two two columns there which means
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that I can only fit two electrons okay
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each column is an electron and so if I
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can only fit two electrons that means I
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only need one orbital because each
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orbital holds two electrons if I go over
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to the P there are six
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columns there okay and look at your
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periodic table right now there are six
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columns there six columns six electrons
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means that I need three orbitals to hold
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that D has ten F has 14 most of the time
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you're like most of the time what does
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that mean well on some periodic tables
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they'll take since the F block goes
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right here
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they'll pull that down and they'll sort
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of put the d1 there and we're not going
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to worry about that at the moment but
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again you could just look at the
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periodic table to be able to figure out
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how many boxes and boxes of course I
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mean orbitals go in each one of them
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okay so that's the basics we're gonna
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work some more complicated ones in the
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next video and then we'll talk about how
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to condense this down to a smaller
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version in the video after that thanks
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kiddos
