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CATHERINE DRENNAN:
That's today's handout.

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We have valence bond
theory and hybridization.

00:00:31.960 --> 00:00:33.895
So some people
ask, OK, now you're

00:00:33.895 --> 00:00:35.770
going to tell me everything
you just learned.

00:00:35.770 --> 00:00:36.860
It's not really
right and there's

00:00:36.860 --> 00:00:38.068
something else that's better.

00:00:38.068 --> 00:00:38.590
No.

00:00:38.590 --> 00:00:41.200
All of these theories
are good theories.

00:00:41.200 --> 00:00:44.140
They all do a very good job
predicting the properties

00:00:44.140 --> 00:00:46.900
of molecules, but they all
have different strengths

00:00:46.900 --> 00:00:47.590
and weaknesses.

00:00:47.590 --> 00:00:50.470
And I think in terms
of what they're useful

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for, molecular orbital theory is
very good in terms of thinking

00:00:54.400 --> 00:00:55.840
about energy levels.

00:00:55.840 --> 00:00:58.240
It's very good about
thinking about bond orders

00:00:58.240 --> 00:01:00.198
or predicting whether
something's going to have

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an unpaired electron or not.

00:01:02.470 --> 00:01:04.810
Valence bond theory
and hybridization

00:01:04.810 --> 00:01:06.400
are really good in
terms of thinking

00:01:06.400 --> 00:01:08.620
about shapes of molecules.

00:01:08.620 --> 00:01:12.010
So not so much about
energy levels, but shapes.

00:01:12.010 --> 00:01:14.590
So all of these theories
are very, very useful

00:01:14.590 --> 00:01:17.650
because we want to think
about how atoms come together

00:01:17.650 --> 00:01:19.840
to form these molecules
and what are the properties

00:01:19.840 --> 00:01:20.800
of the molecules.

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So these theories
brought together really

00:01:23.290 --> 00:01:25.150
give us a wonderful
picture of this.

00:01:25.150 --> 00:01:27.800
And I really like valence
bond theory and hybridization

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because I like shape.

00:01:29.490 --> 00:01:32.890
I determine shapes of molecules,
complicated molecules,

00:01:32.890 --> 00:01:35.800
for a living so I'm a big fan.

00:01:35.800 --> 00:01:40.582
But I will say that when I
taught this the same lecture

00:01:40.582 --> 00:01:42.040
last year, I
announced to the class

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that I had had a dream where
all these atomic orbitals were

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coming together and trying to
make other kinds of orbitals.

00:01:50.764 --> 00:01:52.180
And I realized
that, perhaps, that

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was a sign that
on Friday I should

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start teaching
thermodynamics which is

00:01:56.800 --> 00:01:58.130
what we're going to be doing.

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We're going to start on
thermodynamics on Friday.

00:02:00.190 --> 00:02:04.630
And last night, I had
another dream about orbitals.

00:02:04.630 --> 00:02:10.280
So I think this is
some more orbitals

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and then we go to
thermodynamics.

00:02:13.210 --> 00:02:17.110
And I remembered my dream
because at that moment,

00:02:17.110 --> 00:02:21.340
my giant dog jumped on top
of me as I was sleeping

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to wake me up and realize
that thermodynamics

00:02:24.340 --> 00:02:25.480
needs to come pretty soon.

00:02:25.480 --> 00:02:26.300
OK.

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But one more theory,
valence bond.

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This is not so bad.

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OK.

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Bonds result from the
pairing of unpaired electrons

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from the valence shell
of atomic orbitals.

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That's it.

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That's it.

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So we have one, we
bring in another

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so we can make
molecular hydrogen, H2,

00:02:51.400 --> 00:02:53.950
because they each have
one unpaired electron

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and they come together
to form a bond.

00:02:57.040 --> 00:03:00.910
I like theories that
you can put on a magnet

00:03:00.910 --> 00:03:02.080
on your refrigerator.

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That's a good theory to me.

00:03:04.750 --> 00:03:08.290
So also as part of
valence bond theory,

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we have some names of bonds.

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And we've been talking about
sigma molecular orbitals

00:03:16.390 --> 00:03:18.370
and pi molecular orbitals.

00:03:18.370 --> 00:03:23.500
And now, we're going to talk
about sigma bonds and pi bonds.

00:03:23.500 --> 00:03:28.480
So we had orbitals in MO
theory, valence bond theory,

00:03:28.480 --> 00:03:30.940
we now have bonds.

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Sigma orbital is cylindrically
symmetric about the bonding

00:03:38.050 --> 00:03:38.950
axis.

00:03:38.950 --> 00:03:41.140
Thank goodness they didn't
define them differently.

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That would have
been a nightmare.

00:03:42.620 --> 00:03:46.210
So we have sigma orbitals
that are cylindrically

00:03:46.210 --> 00:03:49.540
symmetrical about the
bond axis and sigma

00:03:49.540 --> 00:03:52.180
bonds are cylindrically
symmetrical about the bond

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axis.

00:03:52.780 --> 00:03:55.360
So no nodal plane
along the bond axis.

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Good.

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We should be able
to remember that.

00:03:59.530 --> 00:04:04.540
So with pi bonds, we have
electron density in two lobes

00:04:04.540 --> 00:04:08.480
with a single nodal plane
along the bond axis.

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So again, with pi
orbitals, we had

00:04:11.890 --> 00:04:14.510
more-- it wasn't
cylindrically symmetric.

00:04:14.510 --> 00:04:18.160
So this we should
be able to remember.

00:04:18.160 --> 00:04:25.300
A couple other things about
sigma bonds and pi bonds,

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a single bond is a sigma bond.

00:04:31.280 --> 00:04:34.760
So when there's one
bond, it's a sigma bond.

00:04:34.760 --> 00:04:36.600
So what's a double bond?

00:04:36.600 --> 00:04:42.830
A double bond is a sigma
bond plus one pi bond.

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So if it's double bond,
it's got two types

00:04:45.190 --> 00:04:47.735
of bonds, sigma and pi.

00:04:47.735 --> 00:04:49.360
And what do you think
a triple bond is?

00:04:52.950 --> 00:04:57.360
Sigma bond and two pi bonds.

00:04:57.360 --> 00:05:02.900
So you got a triple bond like
nitrogen, you got two pi's.

00:05:02.900 --> 00:05:06.030
Hey, it's really a good life
when you have a triple bond.

00:05:06.030 --> 00:05:06.530
All right.

00:05:06.530 --> 00:05:08.530
Single bonds always
going to be sigma.

00:05:08.530 --> 00:05:10.240
Double, sigma and pi.

00:05:10.240 --> 00:05:13.380
Triple, sigma and two pi bonds.

00:05:13.380 --> 00:05:14.980
OK.

00:05:14.980 --> 00:05:19.520
So now we're going to
hybridize our orbitals.

00:05:19.520 --> 00:05:25.000
And we're going to talk about
electron promotion, as well.

00:05:25.000 --> 00:05:27.460
So start with carbon,
carbon based life.

00:05:27.460 --> 00:05:31.090
Carbon is really important and
if you are an organic chemist,

00:05:31.090 --> 00:05:34.780
and by organic, it means
studying things with carbon,

00:05:34.780 --> 00:05:36.460
you care a lot
about hybridization.

00:05:36.460 --> 00:05:38.001
And the stuff I'm
teaching you today,

00:05:38.001 --> 00:05:42.160
you'll see a lot if you go on
to take Organic Chemistry 512.

00:05:42.160 --> 00:05:46.270
So carbon, such as one in
methane, so we have our methane

00:05:46.270 --> 00:05:48.550
molecule here.

00:05:48.550 --> 00:05:53.770
The carbon has four
unpaired-- can form bonds

00:05:53.770 --> 00:05:59.740
with four electrons, but to
do so we need to do something

00:05:59.740 --> 00:06:00.970
with our electrons.

00:06:00.970 --> 00:06:04.420
So carbon comes in, it has
two electrons in it's 2s

00:06:04.420 --> 00:06:08.770
and it has two electrons
in it's 2p's, p orbitals,

00:06:08.770 --> 00:06:11.560
but we want to form four bonds.

00:06:11.560 --> 00:06:14.260
And in covalent bond
theory, every bond

00:06:14.260 --> 00:06:16.630
you bring an electron
from one atom,

00:06:16.630 --> 00:06:18.760
an electron from the
other, and they pair

00:06:18.760 --> 00:06:20.110
and that forms a bond.

00:06:20.110 --> 00:06:25.330
So we don't have four unpaired
electrons to make four bonds

00:06:25.330 --> 00:06:27.820
with this configuration
of electrons,

00:06:27.820 --> 00:06:32.740
so we can talk about promotion
of an electron from here

00:06:32.740 --> 00:06:34.120
up there.

00:06:34.120 --> 00:06:39.850
And if we do that , now we
have our four single unpaired

00:06:39.850 --> 00:06:42.460
electrons ready to
make four bonds.

00:06:42.460 --> 00:06:44.620
And carbon does like
to make four bonds.

00:06:44.620 --> 00:06:46.480
It does it quite often.

00:06:46.480 --> 00:06:49.240
So that's electron promotion.

00:06:49.240 --> 00:06:51.850
To form those four
bonds, a 2s electron

00:06:51.850 --> 00:06:56.470
is promoted to an
empty 2p orbital.

00:06:56.470 --> 00:07:00.920
And then, we can
hybridized our orbitals

00:07:00.920 --> 00:07:04.180
and that means that we want
to give all our orbitals

00:07:04.180 --> 00:07:07.900
some s and some p character.

00:07:07.900 --> 00:07:12.250
So here are our hybrid
orbitals and let

00:07:12.250 --> 00:07:14.050
me show you the nomenclature.

00:07:14.050 --> 00:07:16.085
So we're talking
about n equals two.

00:07:16.085 --> 00:07:17.470
So we have a two.

00:07:17.470 --> 00:07:21.280
We have s character
and we have p character

00:07:21.280 --> 00:07:26.050
and we're using three p orbitals
to make our hybrid orbitals.

00:07:26.050 --> 00:07:31.870
So we are going to make
a 2sp 3 hybrid orbital.

00:07:31.870 --> 00:07:33.670
And we're going to
make four of them

00:07:33.670 --> 00:07:37.560
because we've used four
atomic orbitals to make them.

00:07:37.560 --> 00:07:42.520
So if we are using four,
we need to make four.

00:07:42.520 --> 00:07:45.800
So let's kind of take a look
at what's going on here.

00:07:45.800 --> 00:07:49.090
And we'll say that these
molecular orbitals differ only

00:07:49.090 --> 00:07:52.150
in terms of their
orientation in space.

00:07:52.150 --> 00:07:53.650
So they don't have
different shapes,

00:07:53.650 --> 00:07:56.600
they're just
oriented differently.

00:07:56.600 --> 00:08:01.930
So here we have our 2s,
remember it's symmetric,

00:08:01.930 --> 00:08:06.880
and we have our
three p orbitals,

00:08:06.880 --> 00:08:09.190
and they're all the same
except that they're all

00:08:09.190 --> 00:08:12.650
oriented differently in space.

00:08:12.650 --> 00:08:15.310
And when we bring
these together,

00:08:15.310 --> 00:08:20.560
we form four hybrid orbitals and
they kind of look like turtles,

00:08:20.560 --> 00:08:23.950
but they're turtles oriented
differently in space,

00:08:23.950 --> 00:08:27.610
but otherwise they're the same.

00:08:27.610 --> 00:08:34.000
So those are our sp 3
hybridized orbitals.

00:08:34.000 --> 00:08:40.570
So carbon has this sp
3 hybridized orbital

00:08:40.570 --> 00:08:43.480
and it has four
unpaired electrons

00:08:43.480 --> 00:08:49.430
available to form bonds
with four hydrogens.

00:08:49.430 --> 00:08:53.140
So let's bring our hydrogens
in to form our bonds.

00:08:53.140 --> 00:08:58.490
And each hydrogen brings
with it it's one electron.

00:08:58.490 --> 00:09:02.020
So now we have two
electrons in all four

00:09:02.020 --> 00:09:03.490
of our hybrid orbitals.

00:09:09.160 --> 00:09:12.724
And we can think about
where the energy came from.

00:09:12.724 --> 00:09:14.890
I just moved that electron,
I didn't think about it.

00:09:14.890 --> 00:09:16.930
I'm like, yeah, that
just goes up here.

00:09:16.930 --> 00:09:21.070
So where did the energy
come from to do that?

00:09:21.070 --> 00:09:23.800
And that is, it
came from bonding.

00:09:23.800 --> 00:09:28.660
So this molecule now is more
stable because it's bonded.

00:09:28.660 --> 00:09:30.880
Methane isn't quite
a stable molecule.

00:09:30.880 --> 00:09:33.290
That's another problem
in and of itself.

00:09:33.290 --> 00:09:35.350
So the bonding allows
you to do that.

00:09:35.350 --> 00:09:38.830
You get back from this bonding.

00:09:38.830 --> 00:09:40.840
So let's look at
those bonds then

00:09:40.840 --> 00:09:45.800
that are formed that make that
electron promotion worthwhile.

00:09:45.800 --> 00:09:49.240
And so you're forming a
bond between the carbon

00:09:49.240 --> 00:09:51.760
and the hydrogen,
you're forming for them,

00:09:51.760 --> 00:09:55.930
and you're forming single
bonds, they're sigma bonds,

00:09:55.930 --> 00:10:02.110
and the bond is formed between
the carbon's 2sp 3 orbital

00:10:02.110 --> 00:10:04.780
and the hydrogen's 1s orbital.

00:10:04.780 --> 00:10:10.030
Hydrogen can't hybridize,
it's got one, 1s orbital.

00:10:10.030 --> 00:10:13.250
That's all it's got,
can't do anything else.

00:10:13.250 --> 00:10:16.500
And that gives you a
bond then, a sigma bond,

00:10:16.500 --> 00:10:20.630
that you'll see this a lot
and you'll write this a lot.

00:10:20.630 --> 00:10:23.804
This is how we're going
to name that sigma bond.

00:10:23.804 --> 00:10:24.970
So we're going to say sigma.

00:10:24.970 --> 00:10:26.950
We're going to
have a parentheses.

00:10:26.950 --> 00:10:29.290
Identify the
element, it's carbon.

00:10:29.290 --> 00:10:30.850
N is 2.

00:10:30.850 --> 00:10:35.980
Type of orbital, sp
3 comma hydrogen,

00:10:35.980 --> 00:10:40.620
the name of the other element,
and it's orbital, which is 1s.

00:10:40.620 --> 00:10:45.050
So when it ask you to
name the type of bond,

00:10:45.050 --> 00:10:48.360
this Is the complete answer
that we're looking for.

00:10:48.360 --> 00:10:50.214
And we'll have more
practice on this.

00:10:53.140 --> 00:10:54.960
Now we can also
think about the shape

00:10:54.960 --> 00:10:57.010
that this molecule would have.

00:10:57.010 --> 00:11:01.780
What is the angle here between
this hydrogen and that hydrogen

00:11:01.780 --> 00:11:07.200
and frankly, between any of
the hydrogen carbon hydrogens?

00:11:07.200 --> 00:11:10.830
Yup, 109.5.

00:11:10.830 --> 00:11:14.290
And the name of that geometry?

00:11:14.290 --> 00:11:16.950
Tetrahedral, right.

00:11:16.950 --> 00:11:25.320
So sp 3 gives you a tetrahedral
based geometry here.

00:11:25.320 --> 00:11:25.950
All right.

00:11:25.950 --> 00:11:28.460
So now let's get
more complicated.

00:11:28.460 --> 00:11:29.970
Let's bring two carbons in.

00:11:29.970 --> 00:11:34.120
So we have ethane, two
carbon's, six hydrogens.

00:11:34.120 --> 00:11:39.160
So this also has its
carbons are sp three,

00:11:39.160 --> 00:11:41.530
and this is what we
saw before for methane,

00:11:41.530 --> 00:11:46.320
but now I'm going to rotate this
around and that's one carbon,

00:11:46.320 --> 00:11:49.900
but we need another
carbon, but first we

00:11:49.900 --> 00:11:52.150
can think about this one carbon.

00:11:52.150 --> 00:11:57.040
So one of the carbons of, ethane
it would have this 109.5 angle.

00:11:57.040 --> 00:12:01.000
It has four unpaired electrons
available in it's four

00:12:01.000 --> 00:12:06.130
hybrid orbitals to form
interactions, one with carbon

00:12:06.130 --> 00:12:09.100
and three of them with
hydrogen. And then we

00:12:09.100 --> 00:12:12.550
need another one of these
so we'll bring that in

00:12:12.550 --> 00:12:16.120
and it comes in with its
set of hybrid orbitals

00:12:16.120 --> 00:12:20.070
and it's set of electrons.

00:12:20.070 --> 00:12:22.800
And we form a bond between them.

00:12:22.800 --> 00:12:27.287
And the bond we're going to form
is a single bond, a sigma bond.

00:12:30.120 --> 00:12:32.900
And now let's bring
in our hydrogens.

00:12:32.900 --> 00:12:35.525
So we had six hydrogens,
three for each carbon.

00:12:38.970 --> 00:12:41.220
And so there are now
two types of bonds.

00:12:41.220 --> 00:12:44.140
We have the carbon-carbon
bond and we also

00:12:44.140 --> 00:12:47.650
have the carbon-hydrogen bonds.

00:12:47.650 --> 00:12:51.100
And so the carbon-carbon
bond, which is a sigma bond,

00:12:51.100 --> 00:12:58.090
is sigma (C-- it
has carbon-- 2sp 3,

00:12:58.090 --> 00:13:02.900
the other carbon is the same,
C2sp 3 and then the bracket.

00:13:02.900 --> 00:13:04.270
So that's that sigma bond.

00:13:04.270 --> 00:13:07.030
It's a single bond.

00:13:07.030 --> 00:13:10.360
And here is our ethane molecule.

00:13:13.240 --> 00:13:16.590
And then we have our
carbon hydrogen bonds,

00:13:16.590 --> 00:13:18.100
they're also sigma.

00:13:18.100 --> 00:13:21.250
Please don't give me pi
bonds to hydrogen. It only

00:13:21.250 --> 00:13:23.744
has that one electron
tapping with two electrons.

00:13:23.744 --> 00:13:25.410
It doesn't want do
anything complicated.

00:13:25.410 --> 00:13:27.710
It doesn't have p
orbitals, just that one s.

00:13:27.710 --> 00:13:32.305
So sigma C2sp 3, H1s.

00:13:35.070 --> 00:13:37.000
And now we have
defined this molecule

00:13:37.000 --> 00:13:41.140
so we brought together
two tetrahedral centers

00:13:41.140 --> 00:13:46.300
and formed this molecule
with a single bond.

00:13:46.300 --> 00:13:48.720
So let's talk about
nitrogen. Nitrogen,

00:13:48.720 --> 00:13:52.280
also again, very important.

00:13:52.280 --> 00:13:55.920
So here we have five
valence electrons.

00:13:55.920 --> 00:13:58.340
What about electron promotion?

00:13:58.340 --> 00:14:00.522
Should I do it?

00:14:00.522 --> 00:14:02.460
No.

00:14:02.460 --> 00:14:04.270
Because I mean, you
could put it up here,

00:14:04.270 --> 00:14:07.800
but it can't make any more bonds
so it doesn't really matter.

00:14:07.800 --> 00:14:10.320
So it doesn't occur
because it would not

00:14:10.320 --> 00:14:13.950
increase the number of unpaired
electrons to form bonds,

00:14:13.950 --> 00:14:18.160
but we can hybridize.

00:14:18.160 --> 00:14:21.210
So we can still
hybridize our orbitals

00:14:21.210 --> 00:14:24.370
and we can get four
hybrid orbitals,

00:14:24.370 --> 00:14:26.430
because we're
going to use our 2s

00:14:26.430 --> 00:14:29.800
and all three of
our 2p orbitals.

00:14:29.800 --> 00:14:32.770
So we'll get the same
set of hybrid orbitals.

00:14:32.770 --> 00:14:36.520
But this time, one of them
has two electrons in it.

00:14:36.520 --> 00:14:38.290
So it's not ready
to bond, it's happy

00:14:38.290 --> 00:14:40.090
according to
valence bond theory.

00:14:40.090 --> 00:14:42.990
And these are our alone pairs.

00:14:42.990 --> 00:14:47.080
But we can form three
bonds with these guys

00:14:47.080 --> 00:14:52.150
so let's look at
an example, NH3.

00:14:52.150 --> 00:14:56.650
So now we have our lone pair,
it's in this orbital up here,

00:14:56.650 --> 00:15:00.210
and then we have three
orbitals available for bonding,

00:15:00.210 --> 00:15:04.180
each with an unpaired
electron ready for the three

00:15:04.180 --> 00:15:06.340
atoms of hydrogen to come in.

00:15:06.340 --> 00:15:09.760
So we bring in our
three atoms of hydrogen,

00:15:09.760 --> 00:15:14.020
each came with an
electron, and now

00:15:14.020 --> 00:15:17.490
you can tell me with a
clicker about the angle

00:15:17.490 --> 00:15:19.912
and the geometry
of this molecule.

00:15:32.700 --> 00:15:34.200
Let's just do 10 more seconds.

00:15:54.430 --> 00:15:56.870
All right.

00:15:56.870 --> 00:16:00.860
So this is back to VSEPR again.

00:16:00.860 --> 00:16:03.230
So we have an angle here.

00:16:03.230 --> 00:16:07.430
It's based on an sn 4 system,
one lone pair, three bonded

00:16:07.430 --> 00:16:08.400
atoms.

00:16:08.400 --> 00:16:12.350
So it's based on our
109.5, but those lone pairs

00:16:12.350 --> 00:16:14.030
make for bad
roommates and they're

00:16:14.030 --> 00:16:17.240
pressing all of these
hydrogens together

00:16:17.240 --> 00:16:20.210
and so the angle
is less than 109.5

00:16:20.210 --> 00:16:23.630
and we name this structure
based on the atoms

00:16:23.630 --> 00:16:28.250
we see, not the lone pairs,
so this is trigonal pyramidal.

00:16:28.250 --> 00:16:31.640
And so here we have it
here so we're naming it

00:16:31.640 --> 00:16:35.480
without thinking about the
position of those lone pairs

00:16:35.480 --> 00:16:39.200
that are pressing down on the
bond so it looks trigonal,

00:16:39.200 --> 00:16:41.688
like a triangle, but it's
also a little pyramid.

00:16:44.240 --> 00:16:48.530
So VSEPR-- VSEPR and
hybridization, they just

00:16:48.530 --> 00:16:49.400
go right together.

00:16:49.400 --> 00:16:50.180
It's awesome.

00:16:50.180 --> 00:16:51.230
OK.

00:16:51.230 --> 00:16:53.960
So we can also name
the type of bond.

00:16:53.960 --> 00:17:00.860
So our nitrogen had 2sp 3
hybridization and our hydrogen

00:17:00.860 --> 00:17:04.250
just 1s, it's a sigma
bond, it's a single bond.

00:17:04.250 --> 00:17:10.159
So we named that
sigma N2sp 3, H1s.

00:17:14.420 --> 00:17:19.220
So nitrogen, now we're
going to go back to carbon--

00:17:19.220 --> 00:17:25.750
sorry, to oxygen-- and think
about hybridization of oxygen.

00:17:25.750 --> 00:17:30.290
Oxygen. Should I do
an electron promotion?

00:17:30.290 --> 00:17:30.790
No.

00:17:30.790 --> 00:17:31.873
It's not going to help me.

00:17:31.873 --> 00:17:36.140
It's not going create any more
electrons available to form

00:17:36.140 --> 00:17:41.690
bonds, but I can hybridize
and I can get the same four

00:17:41.690 --> 00:17:47.870
hybrid orbitals, our four 2sp
3 orbitals, but now two of them

00:17:47.870 --> 00:17:51.140
have two electrons
in them and two

00:17:51.140 --> 00:17:54.770
are available to form bonds.

00:17:54.770 --> 00:17:59.690
Oxygen loves to form bonds
with hydrogen and form water,

00:17:59.690 --> 00:18:01.100
most of the planet is water.

00:18:01.100 --> 00:18:04.460
There's a lot of water and water
is really important for life

00:18:04.460 --> 00:18:08.480
so it's great that oxygen and
hydrogen get along so well.

00:18:08.480 --> 00:18:12.590
So the oxygen, again, has two
lone pairs which are here.

00:18:12.590 --> 00:18:16.910
You bring in our hydrogens and
they come with one electron.

00:18:16.910 --> 00:18:21.500
And again, now, it's still a
steric number of four systems,

00:18:21.500 --> 00:18:25.760
so it's less than 109.5,
and it's actually a lot less

00:18:25.760 --> 00:18:28.490
than the nitrogen because you
have those two lone pairs that

00:18:28.490 --> 00:18:32.000
are just taken up so much
room and squeezing together

00:18:32.000 --> 00:18:38.780
these hydrogen atoms over here
creating this 104.5 angle.

00:18:38.780 --> 00:18:41.960
So here we have
our oxygen molecule

00:18:41.960 --> 00:18:45.560
with its two lone pairs
and its two hydrogens,

00:18:45.560 --> 00:18:48.890
and what's the name
of that geometry?

00:18:48.890 --> 00:18:50.182
Bent.

00:18:50.182 --> 00:18:52.785
And again, we have
these polar bonds

00:18:52.785 --> 00:18:55.820
that create a dipole so
it's a polar molecule, which

00:18:55.820 --> 00:18:58.640
is very important in life.

00:18:58.640 --> 00:19:02.090
And we can name that bond.

00:19:02.090 --> 00:19:04.490
It's a sigma bond.

00:19:04.490 --> 00:19:09.215
It's made up of
oxygen O2sp 2, H1s.

00:19:11.911 --> 00:19:12.410
All right.

00:19:12.410 --> 00:19:17.090
So that's sp 3 hybridization.

00:19:17.090 --> 00:19:23.900
Now let's talk about
sp 2 hybridization.

00:19:23.900 --> 00:19:27.920
So sp 2 hybridization.

00:19:27.920 --> 00:19:32.720
So back to our atomic orbitals.

00:19:32.720 --> 00:19:36.380
And now, we're not going
hybridized all of our orbitals.

00:19:36.380 --> 00:19:42.260
We're just going hybridize our
2s and two of our p orbitals.

00:19:42.260 --> 00:19:45.590
So we'll hybridized
these guys and we

00:19:45.590 --> 00:19:51.140
will form three hybrid
orbitals and we will still

00:19:51.140 --> 00:19:54.080
have one un-hybridized orbital.

00:19:54.080 --> 00:20:00.230
We will have 2p y left alone.

00:20:00.230 --> 00:20:02.210
So let's see what this does.

00:20:02.210 --> 00:20:06.810
How is this
hybridization useful?

00:20:06.810 --> 00:20:08.936
So let's talk about boron.

00:20:08.936 --> 00:20:13.160
Boron has three
unpaired electrons,

00:20:13.160 --> 00:20:16.670
but they are not all available
right now to form bonds,

00:20:16.670 --> 00:20:18.840
according to
valence bond theory.

00:20:18.840 --> 00:20:22.820
So here we do want to
do an electron promotion

00:20:22.820 --> 00:20:27.170
to put one of them up
here so that now all three

00:20:27.170 --> 00:20:29.970
are available to form bonds.

00:20:29.970 --> 00:20:35.120
And we can again, hybridize
these three atomic orbitals

00:20:35.120 --> 00:20:38.150
and form three hybrid orbitals.

00:20:38.150 --> 00:20:43.260
So we have three 2sp
2 hybrid orbitals

00:20:43.260 --> 00:20:46.600
and then we still
have our 2 py orbitals

00:20:46.600 --> 00:20:48.060
so don't forget to mark it.

00:20:48.060 --> 00:20:49.230
It seems lonely.

00:20:49.230 --> 00:20:52.630
It's over here, but it's
going to be important later

00:20:52.630 --> 00:20:54.970
so don't feel bad for it, yet.

00:20:54.970 --> 00:20:55.470
All right.

00:20:55.470 --> 00:20:58.670
So boron-- let's think
about these hybrid orbitals

00:20:58.670 --> 00:21:01.230
and how this gives us
the structure that we

00:21:01.230 --> 00:21:04.750
know occurs when we have boron.

00:21:04.750 --> 00:21:09.150
So boron now has its three sp
2 orbitals and these are going

00:21:09.150 --> 00:21:11.940
to lie in a plane
and they're going

00:21:11.940 --> 00:21:13.740
to be as far apart
from each other

00:21:13.740 --> 00:21:16.880
as they can to minimize
electron repulsion.

00:21:16.880 --> 00:21:18.690
And if you're in
a plane, then you

00:21:18.690 --> 00:21:23.010
need-- far apart as you
could be is 120 degrees.

00:21:23.010 --> 00:21:26.220
And this is what gives us
our trigonal planar geometry.

00:21:26.220 --> 00:21:29.820
So we saw that boron formed
these trigonal planar complexes

00:21:29.820 --> 00:21:34.880
before and again, they're
trigonal planar because they're

00:21:34.880 --> 00:21:40.910
like a triangle and they're
in a plane, trigonal planar.

00:21:40.910 --> 00:21:44.390
And we can now bring
in our hydrogens.

00:21:44.390 --> 00:21:47.520
The hydrogens come
with an electron

00:21:47.520 --> 00:21:50.850
so we have an electron
for them and there we

00:21:50.850 --> 00:21:52.950
have our structure.

00:21:52.950 --> 00:21:55.420
We can also name that bond.

00:21:55.420 --> 00:21:57.670
So again we have single bonds.

00:21:57.670 --> 00:22:04.460
So sigma B, for boron,
2sp 2, H1s, and there

00:22:04.460 --> 00:22:07.620
are three of those.

00:22:07.620 --> 00:22:10.680
Carbon-- carbon
can also do this.

00:22:10.680 --> 00:22:14.460
We talked about
carbon being sp 3.

00:22:14.460 --> 00:22:18.120
Carbon can also be sp 2.

00:22:18.120 --> 00:22:21.140
Hybridized carbon is
amazing that's why

00:22:21.140 --> 00:22:23.520
life is based on carbon.

00:22:23.520 --> 00:22:25.870
Carbon can do lots of things.

00:22:25.870 --> 00:22:28.160
So again, we're going
hybridized two p orbitals,

00:22:28.160 --> 00:22:32.340
one s orbital to give
three hybrid orbitals

00:22:32.340 --> 00:22:36.270
and we have our 2py
over here in the corner,

00:22:36.270 --> 00:22:40.210
but don't feel bad for it, it's
going to do something useful.

00:22:40.210 --> 00:22:44.180
So we now have three electrons
in these hybrid orbitals

00:22:44.180 --> 00:22:50.220
and now we have one electron in
our 2py un-hybridized orbital,

00:22:50.220 --> 00:22:51.370
as well.

00:22:51.370 --> 00:22:54.300
So let's see what carbon,
with this kind of arrangement

00:22:54.300 --> 00:22:57.180
of orbitals, can do.

00:22:57.180 --> 00:23:01.680
And again, we're going to
have trigonal planar geometry

00:23:01.680 --> 00:23:05.820
for our 2sp 2 hybrid orbitals.

00:23:05.820 --> 00:23:09.030
So we have carbon there and
these are all in a plane,

00:23:09.030 --> 00:23:14.610
but now coming out of a plane
toward us is this 2py orbital.

00:23:14.610 --> 00:23:19.160
So it's coming out 90 degrees
away from the trigonal planar

00:23:19.160 --> 00:23:21.410
geometry.

00:23:21.410 --> 00:23:24.840
So an example of
sp 2 hybridization

00:23:24.840 --> 00:23:28.530
is in this molecule,
C2H4, and it

00:23:28.530 --> 00:23:32.310
has a double bond, which
means if it's a double bond,

00:23:32.310 --> 00:23:35.220
it has what kind of bonds in it?

00:23:35.220 --> 00:23:37.560
Sigma and pi, right.

00:23:37.560 --> 00:23:41.470
So one sigma, one pi bond.

00:23:41.470 --> 00:23:44.552
So here now, and this is the
trigonal planar geometry.

00:23:44.552 --> 00:23:47.010
It's supposed to be in a plane,
but you can't really see it

00:23:47.010 --> 00:23:48.360
if it's really in a plane.

00:23:48.360 --> 00:23:53.510
But 90 degrees away from that
plane is our 2py orbital.

00:23:53.510 --> 00:23:57.030
We brought in our two hydrogens
so this carbon here, is carbon

00:23:57.030 --> 00:23:59.695
is there, two
hydrogens are there.

00:23:59.695 --> 00:24:02.590
This would be 120 degrees.

00:24:02.590 --> 00:24:04.260
Now we're going to
bring in another one.

00:24:04.260 --> 00:24:05.820
That's the one over here.

00:24:05.820 --> 00:24:07.125
It comes in with it's carbon.

00:24:07.125 --> 00:24:10.380
It comes in with it's
two hydrogens forming

00:24:10.380 --> 00:24:13.710
these single bond, sigma
bonds, between the carbon

00:24:13.710 --> 00:24:15.360
and those hydrogens.

00:24:15.360 --> 00:24:18.450
And now we're going to
form a carbon-carbon bond.

00:24:18.450 --> 00:24:26.610
This carbon-carbon bond is a
sigma bond and so it's C2sp 2,

00:24:26.610 --> 00:24:29.900
C2sp 2, but we're not done.

00:24:29.900 --> 00:24:34.100
We said this is a double bond,
so that's our sigma bond,

00:24:34.100 --> 00:24:36.240
but we need our pi bond.

00:24:36.240 --> 00:24:41.220
And now py, our
un-hybridized orbital,

00:24:41.220 --> 00:24:45.780
is extremely excited because
it can form the pi bond.

00:24:45.780 --> 00:24:49.050
So we form a pi bond
and that's formed

00:24:49.050 --> 00:24:57.660
by our C2py, C2py
un-hybridized orbital.

00:24:57.660 --> 00:25:03.930
And we also have four CH bonds
and those are single bonds,

00:25:03.930 --> 00:25:06.870
those are sigma
bonds, and so they're

00:25:06.870 --> 00:25:14.260
formed by our C2sp 2
carbon and hydrogen 1s.

00:25:14.260 --> 00:25:15.970
And there are four of those.

00:25:15.970 --> 00:25:20.440
So that's an example
of sp 2 hybridization.

00:25:20.440 --> 00:25:22.090
And one thing that's
very important,

00:25:22.090 --> 00:25:25.840
and here you can see
what that molecule looks

00:25:25.840 --> 00:25:28.737
like-- doesn't all fall apart--
so this is a double bond,

00:25:28.737 --> 00:25:30.820
these smaller kits don't
let me make double bonds,

00:25:30.820 --> 00:25:33.490
so I have a sign double bond.

00:25:33.490 --> 00:25:38.050
And you can see the angles and
the geometry of this molecule.

00:25:38.050 --> 00:25:40.510
And another property
of something

00:25:40.510 --> 00:25:43.390
with the double bond like
this is that it's not

00:25:43.390 --> 00:25:45.040
really free to rotate.

00:25:45.040 --> 00:25:47.800
So when you have these two
kind of points of attachment,

00:25:47.800 --> 00:25:50.290
when we have these
orbitals forming

00:25:50.290 --> 00:25:54.370
between your on
hybridized p orbitals,

00:25:54.370 --> 00:25:58.330
that does not allow for
rotation around the double bond.

00:25:58.330 --> 00:26:00.670
So if you're an
organic chemist wanting

00:26:00.670 --> 00:26:03.040
to make a molecule
that's going to be rigid,

00:26:03.040 --> 00:26:05.320
if you put a lot of
double bonds in it,

00:26:05.320 --> 00:26:07.600
it can't twist and
turn very well.

00:26:07.600 --> 00:26:10.510
It's often very rigid
which is useful.

00:26:10.510 --> 00:26:13.690
So we'll stop here
and we'll finish up

00:26:13.690 --> 00:26:19.120
on Friday sp 2 hybridization.

00:26:19.120 --> 00:26:22.270
For the clicker question,
the bone over there on that

00:26:22.270 --> 00:26:24.730
is also the same as
the one on the board.

00:26:24.730 --> 00:26:27.940
The one on the board is
written with atoms in it

00:26:27.940 --> 00:26:32.680
and it has squiggly lines
to abbreviate so make sure

00:26:32.680 --> 00:26:35.590
that your answer is consistent
with the picture on the board,

00:26:35.590 --> 00:26:36.240
as well.

00:26:45.500 --> 00:26:46.960
How we doing?

00:26:46.960 --> 00:26:47.511
OK.

00:26:47.511 --> 00:26:48.010
All right.

00:26:48.010 --> 00:26:50.710
Let's just take 10 more seconds.

00:26:50.710 --> 00:26:53.390
Remember this is a
clicker competition

00:26:53.390 --> 00:26:58.190
so we want to get the right
answer in for your recitation.

00:26:58.190 --> 00:27:00.690
AUDIENCE: [SIDE CONVERSATIONS]

00:27:08.920 --> 00:27:11.740
CATHERINE DRENNAN: All right.

00:27:11.740 --> 00:27:15.910
That's pretty good because
that's the right answer.

00:27:15.910 --> 00:27:16.660
OK.

00:27:16.660 --> 00:27:20.470
So let's just take a look
at this for a minute.

00:27:20.470 --> 00:27:22.160
First let me explain.

00:27:22.160 --> 00:27:24.700
Let's settle down, quiet down.

00:27:24.700 --> 00:27:27.130
Let me just explain
the diagram, too,

00:27:27.130 --> 00:27:31.300
because you'll be
seeing these diagrams.

00:27:31.300 --> 00:27:35.440
So when you just
have a bond, a line,

00:27:35.440 --> 00:27:40.420
and there's no atom indicated,
that means it's carbon.

00:27:40.420 --> 00:27:43.170
Organic chemists, I think,
came up with this rule.

00:27:43.170 --> 00:27:45.760
Carbon, they just said if
nothing's indicated, of course,

00:27:45.760 --> 00:27:46.390
it's carbon.

00:27:46.390 --> 00:27:48.490
Carbon is such an
important element,

00:27:48.490 --> 00:27:52.000
we don't really need to say
more about it than that.

00:27:52.000 --> 00:27:54.320
So you could interpret
this diagram,

00:27:54.320 --> 00:27:57.710
you have a carbon double
bonded to another carbon.

00:27:57.710 --> 00:27:59.740
And then up here,
there's a carbon

00:27:59.740 --> 00:28:03.100
in that ring so I just
put, in this diagram,

00:28:03.100 --> 00:28:05.710
carbon with squigglies,
you'll see that sometimes.

00:28:05.710 --> 00:28:08.020
That means that there's
more atoms there,

00:28:08.020 --> 00:28:10.690
but I'm too lazy to draw them.

00:28:10.690 --> 00:28:12.816
And on this side,
there's a carbon,

00:28:12.816 --> 00:28:15.190
but there's more atoms there
and I'm too lazy to draw it,

00:28:15.190 --> 00:28:16.680
another squiggly.

00:28:16.680 --> 00:28:19.660
And then we have the double bond
so there's a carbon down here,

00:28:19.660 --> 00:28:20.320
as well.

00:28:20.320 --> 00:28:23.080
It wasn't indicated, just
the line in the drawing.

00:28:23.080 --> 00:28:27.010
And you have to predict how many
hydrogens Hydrogens are often

00:28:27.010 --> 00:28:28.420
not indicated.

00:28:28.420 --> 00:28:29.560
This one is indicated.

00:28:29.560 --> 00:28:31.270
There are other
hydrogens in this drawing

00:28:31.270 --> 00:28:32.860
that are not indicated.

00:28:32.860 --> 00:28:35.680
You need to figure
out where they go

00:28:35.680 --> 00:28:38.620
and the material we're doing now
is going to help you do that.

00:28:38.620 --> 00:28:41.140
And then I also drew
something and another squiggly

00:28:41.140 --> 00:28:43.390
because I was too
lazy to draw the rest.

00:28:43.390 --> 00:28:46.090
So these are different
kinds of diagrams

00:28:46.090 --> 00:28:48.460
that you'll see that
all kind of mean

00:28:48.460 --> 00:28:50.290
there's more than one
way to kind of write

00:28:50.290 --> 00:28:53.840
the same structure.

00:28:53.840 --> 00:28:59.320
So this particular molecule
was used to treat schizophrenia

00:28:59.320 --> 00:29:05.050
in the 1950s and key to the
usefulness of the molecule

00:29:05.050 --> 00:29:06.610
was that double bond.

00:29:06.610 --> 00:29:10.390
As we talked about last time,
double bonds restrict movement.

00:29:10.390 --> 00:29:12.580
You can't twist around
the double bond.

00:29:12.580 --> 00:29:16.750
And so if you had exchange and
you had this group over there

00:29:16.750 --> 00:29:20.170
and the hydrogen over here, it
wouldn't be an active molecule.

00:29:20.170 --> 00:29:23.860
So this double bond
fixes the orientation

00:29:23.860 --> 00:29:26.680
of those other atoms such
that it was an active molecule

00:29:26.680 --> 00:29:29.860
and could be used
as a pharmaceutical

00:29:29.860 --> 00:29:31.640
to treat schizophrenia.

00:29:31.640 --> 00:29:33.760
So in terms of
the bonds then, we

00:29:33.760 --> 00:29:36.820
have a double bond which means
we have one sigma and one pi

00:29:36.820 --> 00:29:37.630
bond.

00:29:37.630 --> 00:29:40.420
And so the sigma
bond down here, we

00:29:40.420 --> 00:29:43.720
had to know what the
hybridization was.

00:29:43.720 --> 00:29:49.360
And here, those carbons are
bonded to three other atoms

00:29:49.360 --> 00:29:55.440
and so it would be sp 2 carbons
and also with the double bond

00:29:55.440 --> 00:29:56.620
sp 2.

00:29:56.620 --> 00:29:59.260
And then we also
have a pi bond and pi

00:29:59.260 --> 00:30:05.560
bonds are made up of
non-hybridized orbitals, our py

00:30:05.560 --> 00:30:07.090
or our px.

00:30:07.090 --> 00:30:09.910
And so those are the ones
that make up the pi bond.

00:30:09.910 --> 00:30:11.800
In all the other
variations, some

00:30:11.800 --> 00:30:15.580
you had two sigmas, that's not
right, we have a sigma and a pi

00:30:15.580 --> 00:30:16.900
so most people figure that out.

00:30:16.900 --> 00:30:20.830
They picked the ones that had
those categories for the most

00:30:20.830 --> 00:30:21.886
part.

00:30:21.886 --> 00:30:23.260
And then you had
to pay attention

00:30:23.260 --> 00:30:26.620
to whether it was sp 2 or sp 3.

00:30:26.620 --> 00:30:30.650
And then here, this
one, the pi bond

00:30:30.650 --> 00:30:32.710
is not made up of
hybridized orbitals,

00:30:32.710 --> 00:30:35.240
it's made up of the
atomic orbital leftover.

00:30:35.240 --> 00:30:38.540
So a lot to look at
that particular problem,

00:30:38.540 --> 00:30:42.380
but this is really good
practice for the exam, which is

00:30:42.380 --> 00:30:44.860
coming up a week from Monday.

00:30:44.860 --> 00:30:48.520
There's going to be lots
of hybridization and today,

00:30:48.520 --> 00:30:51.380
we're going to post extra
problems for the exam

00:30:51.380 --> 00:30:53.110
so you have,
really, a whole week

00:30:53.110 --> 00:30:55.300
to start getting
ready for this exam

00:30:55.300 --> 00:30:57.820
and to keep up with
the new material.

00:30:57.820 --> 00:31:00.670
And so extra problems
and an old exam

00:31:00.670 --> 00:31:03.441
are also going to be
posted later today.

00:31:03.441 --> 00:31:03.940
All right.

00:31:03.940 --> 00:31:06.670
So let's just finish
with hybridization now

00:31:06.670 --> 00:31:09.190
and this is good because
this is all stuff that's

00:31:09.190 --> 00:31:10.510
going to be on the exam.

00:31:10.510 --> 00:31:13.480
And also, the
instructions for the exam

00:31:13.480 --> 00:31:17.290
are attached to today's
handouts and, of course,

00:31:17.290 --> 00:31:19.904
remember no makeup exams
and clicker competition.

00:31:19.904 --> 00:31:21.820
So I'm not really going
to go through anything

00:31:21.820 --> 00:31:22.660
in the instructions.

00:31:22.660 --> 00:31:26.260
It's very similar to last time
so you can take a look at that

00:31:26.260 --> 00:31:29.140
and see on the
material, the material

00:31:29.140 --> 00:31:32.170
starts with the periodic
table, periodic trends,

00:31:32.170 --> 00:31:34.090
and goes through the
material that I'm

00:31:34.090 --> 00:31:36.710
going to finish with partway
through today's lecture.

00:31:36.710 --> 00:31:38.800
So at the end of
hybridization, that's

00:31:38.800 --> 00:31:42.100
the end of exam two material.

00:31:42.100 --> 00:31:44.800
So we're going to finish our
lecture notes from last time

00:31:44.800 --> 00:31:46.360
so pull those out.

00:31:46.360 --> 00:31:48.830
And then we're going to
move on to thermodynamics.

00:31:48.830 --> 00:31:52.540
So once we hit thermodynamics,
that's exam three material,

00:31:52.540 --> 00:31:56.170
so we're almost done with exam
two material, a week in advance

00:31:56.170 --> 00:31:57.620
to get ready for the exam.

00:31:57.620 --> 00:31:58.690
So that's great.

00:31:58.690 --> 00:32:02.020
Lots of time to review
exam two material

00:32:02.020 --> 00:32:06.380
and let's see if we can have
an A average on this exam.

00:32:06.380 --> 00:32:08.770
That would make me really,
really really, happy.

00:32:08.770 --> 00:32:13.120
I would wear my periodic
table leggings again

00:32:13.120 --> 00:32:16.270
if we could get an A
average on the exam.

00:32:16.270 --> 00:32:19.420
I'm just saying,
I'd be very excited.

00:32:19.420 --> 00:32:20.800
OK.

00:32:20.800 --> 00:32:23.290
So we better finish
up that material

00:32:23.290 --> 00:32:27.730
so that you can get
started, get ready for this.

00:32:27.730 --> 00:32:31.810
So we talking about valence
bond theory and hybridization

00:32:31.810 --> 00:32:34.060
and forming these
hybrid orbitals.

00:32:34.060 --> 00:32:36.430
And valence bond
theory is this idea

00:32:36.430 --> 00:32:39.760
that if you have a single
electron in an orbital,

00:32:39.760 --> 00:32:43.180
it's available to form a
bond and bonding happens when

00:32:43.180 --> 00:32:46.300
two atoms bring together
single electrons

00:32:46.300 --> 00:32:49.010
and those pair up
to form a bond.

00:32:49.010 --> 00:32:51.340
So we talked about
electron promotion

00:32:51.340 --> 00:32:54.430
before and let's just
review what that meant.

00:32:54.430 --> 00:32:58.270
So if you have an
empty orbital, you

00:32:58.270 --> 00:33:00.670
can promote one
of your electrons

00:33:00.670 --> 00:33:02.620
to that empty orbital.

00:33:02.620 --> 00:33:05.470
And so now we have
four valence electrons

00:33:05.470 --> 00:33:10.450
after electron promotion so
that we have more possibility

00:33:10.450 --> 00:33:11.800
of forming bonds.

00:33:11.800 --> 00:33:14.440
Now if you don't have
an empty orbital,

00:33:14.440 --> 00:33:16.390
you can't promote your electron.

00:33:16.390 --> 00:33:18.250
If you do have an
empty orbital, you

00:33:18.250 --> 00:33:21.040
can promote it more
single electrons

00:33:21.040 --> 00:33:22.510
available for bonding.

00:33:22.510 --> 00:33:25.150
If you don't have
an empty orbital,

00:33:25.150 --> 00:33:26.980
there's nothing to do with that.

00:33:26.980 --> 00:33:30.591
So that's the trick
to electron promotion.

00:33:30.591 --> 00:33:31.090
All right.

00:33:31.090 --> 00:33:36.340
So now we have one electron
in each of the four

00:33:36.340 --> 00:33:41.020
valence atomic orbitals
that we have for carbon,

00:33:41.020 --> 00:33:44.680
but we're going to only
hybridize two of them.

00:33:44.680 --> 00:33:50.170
We saw already last time that we
can hybridize all four orbitals

00:33:50.170 --> 00:33:51.670
and have sp 3.

00:33:51.670 --> 00:33:55.894
We can hybridize just three of
those orbitals and have sp 2.

00:33:55.894 --> 00:33:57.310
Now we're going
to see that we can

00:33:57.310 --> 00:34:00.860
hybridize just two of
those orbitals and have sp.

00:34:00.860 --> 00:34:02.840
So carbon is really amazing.

00:34:02.840 --> 00:34:06.070
It can do all three of these
kinds of hybridization.

00:34:06.070 --> 00:34:08.560
That's why carbon
based life forms

00:34:08.560 --> 00:34:11.710
are able to exist
and do so much.

00:34:11.710 --> 00:34:16.690
So we're going to now hybridize
our 2s and our two pz.

00:34:16.690 --> 00:34:22.420
Z is just special and
so it gets to hybridize

00:34:22.420 --> 00:34:27.280
with the 2s leaving two
of the other orbitals

00:34:27.280 --> 00:34:28.880
just by themselves.

00:34:28.880 --> 00:34:31.389
So we're going to form
two hybrid orbitals.

00:34:31.389 --> 00:34:34.040
Again, if we hybridize
two atomic orbitals,

00:34:34.040 --> 00:34:37.000
we're going to form
two hybrid orbitals.

00:34:37.000 --> 00:34:40.270
And if we hybridized
2s and 2pz, we're

00:34:40.270 --> 00:34:43.840
going to get hybrid
2sp orbitals.

00:34:43.840 --> 00:34:50.831
And we'll have our 2px and our
2py just the same as always.

00:34:50.831 --> 00:34:51.330
All right.

00:34:51.330 --> 00:34:54.810
So we can think about this
in terms of shapes, as well.

00:34:54.810 --> 00:34:59.210
So we have, again, our
spherically symmetric

00:34:59.210 --> 00:35:02.190
s orbitals and our
p orbitals and we

00:35:02.190 --> 00:35:04.740
have the three of
our p orbitals that

00:35:04.740 --> 00:35:08.610
are the same shape they just
differ in orientation in space.

00:35:08.610 --> 00:35:13.640
And so we're just going
hybridize our 2pz and our 2s

00:35:13.640 --> 00:35:15.810
and so we'll have our
kind of funny looking

00:35:15.810 --> 00:35:19.530
I think of them as turtle
shaped or hybrid orbitals

00:35:19.530 --> 00:35:24.930
and then we also have
our 2px and 2py orbitals

00:35:24.930 --> 00:35:26.640
the same as always.

00:35:26.640 --> 00:35:32.120
So what are we going to do with
our two sp orbitals and our one

00:35:32.120 --> 00:35:35.610
2px and one 2py?

00:35:35.610 --> 00:35:39.120
Well, we can form a pretty
cool molecule with it.

00:35:39.120 --> 00:35:40.860
So we're going to form
something that has

00:35:40.860 --> 00:35:43.050
a carbon-carbon triple bond.

00:35:43.050 --> 00:35:46.140
So this is C2H2.

00:35:46.140 --> 00:35:49.680
So now in cyan is
the sp orbital,

00:35:49.680 --> 00:35:55.800
the hybrid orbital, that is
formed on this carbon here.

00:35:55.800 --> 00:36:01.590
And then we have
a 2px orbital here

00:36:01.590 --> 00:36:04.440
in the plane of the screen.

00:36:04.440 --> 00:36:10.230
And we have a 2py orbital
coming out toward us.

00:36:10.230 --> 00:36:12.210
And, of course,
our 2pz orbital had

00:36:12.210 --> 00:36:14.820
been hybridized with the 2s.

00:36:14.820 --> 00:36:18.000
So here we have this structure.

00:36:18.000 --> 00:36:21.140
We're going to bring
in our other carbon,

00:36:21.140 --> 00:36:25.050
and the other carbon has
the same situation going on.

00:36:25.050 --> 00:36:29.010
And we can form a bond
between the two carbons

00:36:29.010 --> 00:36:35.220
with our sp orbitals.

00:36:35.220 --> 00:36:39.780
And we can form, also, with
the sp hybrid orbitals, bonds

00:36:39.780 --> 00:36:43.230
to hydrogen. So we have two
hydrogens, one over here

00:36:43.230 --> 00:36:45.340
and one over there.

00:36:45.340 --> 00:36:52.780
So what is the angle between
these hydrogens here?

00:36:52.780 --> 00:36:53.280
Yeah.

00:36:53.280 --> 00:36:58.590
So that's 180 and,
again, we have an example

00:36:58.590 --> 00:37:00.930
here of the molecule we're
going to build that's going

00:37:00.930 --> 00:37:02.397
to have a triple bond.

00:37:05.290 --> 00:37:11.310
So now let's name
those types of bonds

00:37:11.310 --> 00:37:13.515
or as sometimes
in problem set, it

00:37:13.515 --> 00:37:16.830
will say describe the
symmetry of the bond.

00:37:16.830 --> 00:37:19.680
And what it means by
that is the following.

00:37:19.680 --> 00:37:22.770
It means that, that's either
say name the type of bond

00:37:22.770 --> 00:37:24.870
or describe the symmetry.

00:37:24.870 --> 00:37:26.640
There's multiple ways
to ask the question

00:37:26.640 --> 00:37:29.910
and this is the answer
to those questions.

00:37:29.910 --> 00:37:32.550
So the bond that's formed,
the first one that's formed,

00:37:32.550 --> 00:37:35.400
between the two
carbons is a sigma bond

00:37:35.400 --> 00:37:38.400
and it's formed
between the sp orbital.

00:37:38.400 --> 00:37:39.150
So C2sp, C2sp.

00:37:42.330 --> 00:37:43.950
That's the first one.

00:37:43.950 --> 00:37:48.310
But this is a triple bond so
we have two more bonds to form.

00:37:48.310 --> 00:37:54.570
And this is where our atomic px
and py orbitals will come in.

00:37:54.570 --> 00:37:57.300
So we're going to form the
next bond, which is what?

00:37:57.300 --> 00:38:00.090
A sigma or pi?

00:38:00.090 --> 00:38:05.070
Pi bond and that can be
between our x, px, orbitals,

00:38:05.070 --> 00:38:08.595
so pi C2px, C2px.

00:38:11.490 --> 00:38:16.200
And now, we have the
2py orbitals, as well,

00:38:16.200 --> 00:38:19.710
and that allows us to
form our triple bond.

00:38:19.710 --> 00:38:28.440
So we're also going to
have a bond pi C2py, C2py.

00:38:28.440 --> 00:38:30.630
So again, with the
triple bond, we're

00:38:30.630 --> 00:38:34.470
going to have one
sigma and two pi bonds.

00:38:34.470 --> 00:38:37.910
The sigma is formed
from the hybrid orbitals

00:38:37.910 --> 00:38:45.810
and the pi bonds are formed
by the 2px and 2py orbitals.

00:38:45.810 --> 00:38:49.050
So carbon, really impressive.

00:38:49.050 --> 00:38:53.460
Carbon can form of these three
types of hybrid orbitals.

00:38:53.460 --> 00:38:55.860
It can form molecules with
single bonds, double bonds,

00:38:55.860 --> 00:38:57.176
and triple bonds.

00:38:57.176 --> 00:38:58.800
So let's just have
a little cheat sheet

00:38:58.800 --> 00:39:00.960
to think about that.

00:39:00.960 --> 00:39:04.620
So again, this is for carbon
hydrocarbon molecules,

00:39:04.620 --> 00:39:09.460
like we've looked at so far,
that have two carbons in them.

00:39:09.460 --> 00:39:15.870
So let's look at carbon in
C2H6, so that's over here.

00:39:15.870 --> 00:39:19.350
What is going to be
the hybridization when

00:39:19.350 --> 00:39:23.100
you have a carbon that has
a bond to another carbon

00:39:23.100 --> 00:39:26.310
and a bond to three
hydrogens here?

00:39:26.310 --> 00:39:29.550
What hybridization?

00:39:29.550 --> 00:39:30.210
sp 3.

00:39:30.210 --> 00:39:30.864
That's right.

00:39:30.864 --> 00:39:33.030
And it's going to have what
kind of a bond-- single,

00:39:33.030 --> 00:39:34.351
double, or triple?

00:39:34.351 --> 00:39:37.140
It's going to have a
single bond and it's

00:39:37.140 --> 00:39:39.620
going to have
tetrahedral geometry

00:39:39.620 --> 00:39:41.514
around both of the carbons.

00:39:41.514 --> 00:39:42.930
So both of these
carbons are going

00:39:42.930 --> 00:39:45.090
to have tetrahedral
geometry, which

00:39:45.090 --> 00:39:49.320
is not a blank in your
note, but what's the angle?

00:39:49.320 --> 00:39:52.590
109.5, right.

00:39:52.590 --> 00:39:54.410
Thank you.

00:39:54.410 --> 00:40:01.417
So we have carbons C2H2 are
going to be sp 2 hybridized.

00:40:01.417 --> 00:40:03.000
And what kind of a
bond are they going

00:40:03.000 --> 00:40:05.290
to have between the two carbons?

00:40:05.290 --> 00:40:06.840
That will be a double bond.

00:40:06.840 --> 00:40:10.190
And what is the
geometry of that?

00:40:10.190 --> 00:40:10.690
Right.

00:40:10.690 --> 00:40:12.270
Trigonal planar.

00:40:12.270 --> 00:40:14.740
And here, you have to pretend
this is a double bond,

00:40:14.740 --> 00:40:17.760
my model kit didn't come with
double bond possibilities

00:40:17.760 --> 00:40:20.430
and I have to hold
it very carefully,

00:40:20.430 --> 00:40:26.670
but if I hold it very y-- oh--
the bonds are still there.

00:40:26.670 --> 00:40:30.040
You'll see that
the angles are 120

00:40:30.040 --> 00:40:34.590
and so this is trigonal planar
geometry at each carbon.

00:40:34.590 --> 00:40:35.880
We didn't tape that one.

00:40:35.880 --> 00:40:38.700
You can see there's scotch
tape all over the others.

00:40:38.700 --> 00:40:40.620
It was not a happy molecule.

00:40:40.620 --> 00:40:41.400
OK.

00:40:41.400 --> 00:40:46.550
So now, C2H2, what
kind of hybridization?

00:40:46.550 --> 00:40:50.580
sp, that is our
friend the triple bond

00:40:50.580 --> 00:40:54.330
and we're going to have
linear geometry and 180.

00:40:54.330 --> 00:40:58.410
So both carbons have
linear geometry.

00:40:58.410 --> 00:40:59.620
That works.

00:40:59.620 --> 00:41:02.250
It's always triple bonds
are much more stable,

00:41:02.250 --> 00:41:03.610
they don't fall apart as much.

00:41:03.610 --> 00:41:04.110
OK.

00:41:04.110 --> 00:41:06.150
So that's a cheat
sheet for carbon.

00:41:06.150 --> 00:41:09.510
Now if you're thinking
about nitrogen or oxygen,

00:41:09.510 --> 00:41:11.970
those often have
lone pairs on them.

00:41:11.970 --> 00:41:14.190
Carbon likes to
form all bonds, it

00:41:14.190 --> 00:41:16.820
doesn't care double,
triple, single, whatever,

00:41:16.820 --> 00:41:19.650
but it doesn't really have
a lot of lone pairs on it.

00:41:19.650 --> 00:41:22.475
But oxygen, nitrogen
have lone pairs

00:41:22.475 --> 00:41:23.850
and whenever you
have lone pairs,

00:41:23.850 --> 00:41:26.100
you have to worry about
what the geometry is

00:41:26.100 --> 00:41:29.190
because the geometry gets
named based on the atoms

00:41:29.190 --> 00:41:31.480
that you do see,
not the lone pairs.

00:41:31.480 --> 00:41:35.031
So this cheat sheet works for
carbon without lone pairs.

00:41:35.031 --> 00:41:37.530
If you have lone pairs, you've
got to go back to your vesper

00:41:37.530 --> 00:41:40.751
and think about what the
names of the geometries are.

00:41:40.751 --> 00:41:41.250
OK.

00:41:41.250 --> 00:41:43.380
So rules, and I
posted this on Steller

00:41:43.380 --> 00:41:47.550
for the problem set
that was due today,

00:41:47.550 --> 00:41:51.750
and so very simple for
determining hybridization.

00:41:51.750 --> 00:41:54.080
And this is the kind of
equation that will not

00:41:54.080 --> 00:41:56.530
be on an equation
sheet for an exam,

00:41:56.530 --> 00:41:57.840
you just need to know that.

00:41:57.840 --> 00:42:01.350
So in determining
hybridization of an atom

00:42:01.350 --> 00:42:03.030
in a complex
molecule, you're going

00:42:03.030 --> 00:42:06.120
to be thinking about the number
of bonded atoms plus the number

00:42:06.120 --> 00:42:08.850
of lone pairs is going
to be equal to the number

00:42:08.850 --> 00:42:11.820
of hybrid orbitals.

00:42:11.820 --> 00:42:15.420
So now, clicker
question, what is

00:42:15.420 --> 00:42:17.340
the hybridization
of an atom that has

00:42:17.340 --> 00:42:19.700
exactly two hybrid orbitals?

00:42:32.610 --> 00:42:33.180
All right.

00:42:33.180 --> 00:42:33.861
10 seconds.

00:42:48.690 --> 00:42:50.490
Yes.

00:42:50.490 --> 00:42:51.070
Right.

00:42:51.070 --> 00:42:53.340
sp.

00:42:53.340 --> 00:42:56.490
So we can take a look at that
two hybrid orbitals are formed

00:42:56.490 --> 00:43:00.810
by one at 1s orbital
and 1p orbital

00:43:00.810 --> 00:43:04.440
and if you have two things
bonded and no lone pairs,

00:43:04.440 --> 00:43:06.960
that's what you would get.

00:43:06.960 --> 00:43:15.930
Three hybrid orbitals would be
sp 2 and four would be sp 3.

00:43:15.930 --> 00:43:17.760
So again, you're going
to just be thinking

00:43:17.760 --> 00:43:19.980
in these problems
about how many atoms

00:43:19.980 --> 00:43:24.030
are bonded to that central
atom and how many lone pairs do

00:43:24.030 --> 00:43:24.870
you have.

00:43:24.870 --> 00:43:27.840
And that's going to
then let you figure out

00:43:27.840 --> 00:43:29.850
what your hybridization is.

00:43:29.850 --> 00:43:32.910
And we have one
exception which is

00:43:32.910 --> 00:43:36.660
that if an atom
has a single bond

00:43:36.660 --> 00:43:40.050
and it's terminal on the
edge of the molecule, then

00:43:40.050 --> 00:43:42.870
we're not going hybridize it.

00:43:42.870 --> 00:43:47.680
So we can now take a look
at an example of this

00:43:47.680 --> 00:43:50.854
and this is going to
be another-- yeah,

00:43:50.854 --> 00:43:52.020
just keep your clickers out.

00:43:52.020 --> 00:43:54.144
We've got a whole bunch of
clicker questions coming

00:43:54.144 --> 00:43:56.760
at you kind of in a row here.

00:43:56.760 --> 00:44:00.750
And if we have this molecule,
it has a central carbon

00:44:00.750 --> 00:44:03.270
and three terminal atoms.

00:44:03.270 --> 00:44:08.910
Now help me figure out what
kinds of bonds this will form.

00:44:08.910 --> 00:44:12.840
So which one of these
has the correct bond

00:44:12.840 --> 00:44:14.610
types for this molecule?

00:44:34.510 --> 00:44:36.070
All right.

00:44:36.070 --> 00:44:37.510
Make a decision.

00:44:37.510 --> 00:44:39.200
Let's just take 10 more seconds.

00:44:55.960 --> 00:44:56.862
Interesting.

00:44:59.510 --> 00:45:03.640
I think some time I re-poll,
but I think that we'll just kind

00:45:03.640 --> 00:45:11.890
of go over this one and then
we'll-- do you want to go ahead

00:45:11.890 --> 00:45:14.173
and show the answer
and then-- this is--

00:45:14.173 --> 00:45:18.310
AUDIENCE: [SIDE CONVERSATIONS]

00:45:18.310 --> 00:45:20.740
CATHERINE DRENNAN: And if it
wasn't a clicker competition,

00:45:20.740 --> 00:45:22.930
I might have you discuss
it more and re-poll,

00:45:22.930 --> 00:45:24.140
but it's a competition.

00:45:24.140 --> 00:45:25.300
So let's go over it.

00:45:25.300 --> 00:45:29.410
So this one isn't in
your notes so if you

00:45:29.410 --> 00:45:31.720
want to write it at
the bottom of the page,

00:45:31.720 --> 00:45:33.724
we'll go over what
the answer is.

00:45:33.724 --> 00:45:35.140
Hopefully there's
a typo in there,

00:45:35.140 --> 00:45:36.514
but we'll see when
we go through.

00:45:36.514 --> 00:45:37.660
All right.

00:45:37.660 --> 00:45:42.850
So let's take a look
at this molecule.

00:45:42.850 --> 00:45:45.450
Hydrogen is terminal
and single bonded,

00:45:45.450 --> 00:45:47.200
but we've already
talked about hydrogen

00:45:47.200 --> 00:45:48.670
so we kind of knew that.

00:45:48.670 --> 00:45:52.810
Oxygen is terminal,
but it's double bonded

00:45:52.810 --> 00:45:55.180
so we need to hybridize it.

00:45:55.180 --> 00:46:02.350
Cl is terminal and single bonded
so we don't hybridize this

00:46:02.350 --> 00:46:06.040
and we don't hybridize hydrogen,
never hybridized hydrogen. OK.

00:46:06.040 --> 00:46:08.620
So let's look at the kind
of bonds that are formed.

00:46:08.620 --> 00:46:16.940
So we have a sigma bond, single
bond, this carbon is C2sp 2.

00:46:16.940 --> 00:46:19.510
It's bonded to three
different things

00:46:19.510 --> 00:46:25.220
and it has no lone pairs
so that makes it three

00:46:25.220 --> 00:46:26.970
that there's three
things so we have three

00:46:26.970 --> 00:46:30.040
hybrid orbitals, which is sp 2.

00:46:30.040 --> 00:46:33.120
Our hydrogen is just
1s, it's always just 1s.

00:46:33.120 --> 00:46:35.010
That's all it is.

00:46:35.010 --> 00:46:38.310
So let's look at this bond now.

00:46:38.310 --> 00:46:43.950
So we have a single bond
between our carbon that is 2sp 2

00:46:43.950 --> 00:46:47.010
and then, we also
have this oxygen.

00:46:47.010 --> 00:46:50.460
We do hybridize it because
it has a double bond

00:46:50.460 --> 00:46:53.220
and it has two
sets of lone pairs

00:46:53.220 --> 00:46:55.230
and it's bonded
to one atom, so it

00:46:55.230 --> 00:47:00.570
has three hybrid orbitals, so
it's sp 2 just like the carbon.

00:47:00.570 --> 00:47:03.270
And then we have a pi
bond and the pi bond

00:47:03.270 --> 00:47:07.080
is made up of atomic
orbitals, either 2px or 2py.

00:47:09.990 --> 00:47:13.800
Chlorine is single
bonded so we're not

00:47:13.800 --> 00:47:17.370
going to hybridize it
because it is single bonded

00:47:17.370 --> 00:47:18.750
and it's terminal.

00:47:18.750 --> 00:47:24.600
So it's a single bond, it's
from this carbon that's C2sp 2,

00:47:24.600 --> 00:47:29.490
we already saw that,
and then the chlorine is

00:47:29.490 --> 00:47:35.230
going to be terminal
and so it's Cl3pz

00:47:35.230 --> 00:47:38.337
and so that's a
non-hybridized orbital.

00:47:45.020 --> 00:47:48.420
So good practice
for the clicker.

00:47:48.420 --> 00:47:51.620
I think that one
could help, but we're

00:47:51.620 --> 00:47:54.110
going to have more practice now.

00:47:54.110 --> 00:47:58.134
I threw in a bunch of extra
problems so that one was extra

00:47:58.134 --> 00:48:00.050
and now, let's do the
one that is in the notes

00:48:00.050 --> 00:48:04.400
from last time,
which is vitamin C.

00:48:04.400 --> 00:48:08.990
So I'll give you another minute
if everyone has that one down.

00:48:08.990 --> 00:48:10.910
OK.

00:48:10.910 --> 00:48:16.400
So let's look at
vitamin C. So vitamin C

00:48:16.400 --> 00:48:21.200
is needed to form
collagen in your body.

00:48:21.200 --> 00:48:27.930
Without enough vitamin C in your
diet, you could be in trouble.

00:48:27.930 --> 00:48:30.649
So it doesn't happen
too much anymore

00:48:30.649 --> 00:48:32.690
because there's vitamin
supplements and all sorts

00:48:32.690 --> 00:48:37.100
of things, but often, vitamin
C deficiency is associated

00:48:37.100 --> 00:48:42.050
with sailors who went out to sea
and didn't have a healthy diet

00:48:42.050 --> 00:48:46.130
and they became deficient
in vitamin C and got scurvy.

00:48:46.130 --> 00:48:47.867
And so then they
had to figure out

00:48:47.867 --> 00:48:49.700
they had to eat oranges
or other things that

00:48:49.700 --> 00:48:54.110
were rich in vitamin C. In
terms of who should be concerned

00:48:54.110 --> 00:48:59.960
about vitamin C deficiency, us,
primates, we don't make vitamin

00:48:59.960 --> 00:49:03.050
C, so we have to get it in our
diet and also, Guinea pigs.

00:49:03.050 --> 00:49:04.290
Most other animals make it.

00:49:04.290 --> 00:49:07.280
I don't really know why-- maybe
this is why Guinea pigs are

00:49:07.280 --> 00:49:10.460
called Guinea pigs, they're
good for scurvy experiments

00:49:10.460 --> 00:49:14.150
because they don't make
vitamin C. All right.

00:49:14.150 --> 00:49:17.090
So let's look at this
vitamin C molecule

00:49:17.090 --> 00:49:19.190
and think about what
type of molecule

00:49:19.190 --> 00:49:21.560
it is and this is
a quicker question.

00:49:21.560 --> 00:49:23.810
So we have to remember
back more material that's

00:49:23.810 --> 00:49:25.730
going to be on exam two.

00:49:25.730 --> 00:49:29.300
Does that look like a
polar or non-polar molecule

00:49:29.300 --> 00:49:32.520
and what's true about polar
and non-polar molecules?

00:49:47.160 --> 00:49:48.350
All right 10 more seconds.

00:50:03.436 --> 00:50:03.936
Great.

00:50:08.220 --> 00:50:13.990
So it is polar and it,
therefore, water soluble

00:50:13.990 --> 00:50:19.200
and so you know that because
if there's atoms in there that

00:50:19.200 --> 00:50:21.360
have differences of
electronegativity

00:50:21.360 --> 00:50:25.320
of greater than 0.4, carbon
and oxygen of a difference

00:50:25.320 --> 00:50:28.020
in electronegativity
of greater than 0.4,

00:50:28.020 --> 00:50:32.190
oxygen hydrogen also,
electronegativity

00:50:32.190 --> 00:50:34.200
differences greater than 0.4.

00:50:34.200 --> 00:50:36.540
So we have a lot of polar
bonds and they're not

00:50:36.540 --> 00:50:37.770
canceling each other out.

00:50:37.770 --> 00:50:40.260
It's not a symmetric
molecule so therefore, it

00:50:40.260 --> 00:50:43.480
would be a polar molecule
and water soluble.

00:50:43.480 --> 00:50:43.980
OK.

00:50:43.980 --> 00:50:44.480
Great.

00:50:44.480 --> 00:50:48.450
So you're good on your polar
covalent bonds which is also

00:50:48.450 --> 00:50:49.871
going to be on exam two.

00:50:49.871 --> 00:50:50.370
All right.

00:50:50.370 --> 00:50:51.920
So let's go back
to hybridization

00:50:51.920 --> 00:50:53.970
and have a little
more practice on that.

00:50:53.970 --> 00:50:55.980
So don't put your clickers away.

00:50:55.980 --> 00:50:58.470
Why don't you tell
me the hybridization

00:50:58.470 --> 00:51:04.950
of carbon a labeled up
here and in your notes.

00:51:12.710 --> 00:51:13.210
All right.

00:51:13.210 --> 00:51:14.071
10 more seconds.

00:51:28.980 --> 00:51:30.930
All right.

00:51:30.930 --> 00:51:33.510
So we know what
clicker questions are

00:51:33.510 --> 00:51:36.280
going to determine the winners.

00:51:36.280 --> 00:51:36.780
OK.

00:51:36.780 --> 00:51:41.040
So carbon a was sp 3 hybridized.

00:51:41.040 --> 00:51:45.870
So if we look at it over here,
it has bonded to four things

00:51:45.870 --> 00:51:50.320
so there's four
which makes it sp 3.

00:51:50.320 --> 00:51:50.820
OK.

00:51:50.820 --> 00:51:55.050
So let's just do the rest
and you can yell these out.

00:51:55.050 --> 00:52:00.956
Carbon labeled b, what kind
of hybridization for carbon b?

00:52:00.956 --> 00:52:02.255
AUDIENCE: Sp 3.

00:52:02.255 --> 00:52:04.860
CATHERINE DRENNAN: Sp 3.

00:52:04.860 --> 00:52:06.770
Carbon c?

00:52:06.770 --> 00:52:08.510
AUDIENCE: Sp 3.

00:52:08.510 --> 00:52:10.100
CATHERINE DRENNAN: Sp 3.

00:52:10.100 --> 00:52:12.450
Again, you just want
to count how many bonds

00:52:12.450 --> 00:52:17.730
you have going on or lone pairs,
but carbon doesn't usually

00:52:17.730 --> 00:52:18.990
like to have lone pairs.

00:52:18.990 --> 00:52:20.430
What about carbon d?

00:52:20.430 --> 00:52:21.860
AUDIENCE: sp 2.

00:52:21.860 --> 00:52:23.651
CATHERINE DRENNAN: Sp 2.

00:52:23.651 --> 00:52:24.150
Right.

00:52:24.150 --> 00:52:29.960
It only has-- if we look
at that one over here,

00:52:29.960 --> 00:52:33.210
I'm supposed to point to this
one-- so carbon d over here,

00:52:33.210 --> 00:52:37.890
it has three atoms
that it's bound to.

00:52:37.890 --> 00:52:39.172
Carbon e?

00:52:41.944 --> 00:52:48.800
sp 2 and carbon f?

00:52:48.800 --> 00:52:49.440
AUDIENCE: sp 2.

00:52:49.440 --> 00:52:50.440
CATHERINE DRENNAN: Sp 2.

00:52:50.440 --> 00:52:51.810
Right.

00:52:51.810 --> 00:52:56.250
So now that we did that,
we can use this information

00:52:56.250 --> 00:52:58.800
when we think about
the bonds that

00:52:58.800 --> 00:53:03.850
are formed between these
carbons and the other atoms.

00:53:03.850 --> 00:53:08.140
So let's look at bonding now.

00:53:08.140 --> 00:53:12.480
So if we look at
carbon b, two hydrogen,

00:53:12.480 --> 00:53:15.720
that's going to be a sigma
bond, and you told me

00:53:15.720 --> 00:53:19.710
that carbon b was sp
3 so we write that.

00:53:19.710 --> 00:53:21.840
So describe the symmetry
around the bond,

00:53:21.840 --> 00:53:32.530
name the bond, C2sp 3, H1s,
we do not hybridize hydrogen.

00:53:32.530 --> 00:53:38.790
So now, for the bond between
b and a, again, a sigma bond.

00:53:38.790 --> 00:53:45.180
We already looked at the
fact that carbon b is 2sp 3,

00:53:45.180 --> 00:53:48.720
carbon a was the same.

00:53:48.720 --> 00:53:55.740
Now if we look at the difference
between b and c, b was C2sp 3

00:53:55.740 --> 00:53:58.050
and then c is also the same.

00:53:58.050 --> 00:53:59.690
Remember to write
the twos, remember

00:53:59.690 --> 00:54:02.260
to write the hybridization,
remember to write the element,

00:54:02.260 --> 00:54:05.280
remember to write sigma
for the single bond.

00:54:05.280 --> 00:54:08.510
Grading these questions
on the exam is not fun.

00:54:08.510 --> 00:54:11.100
You've got to remember to
have all those things in there

00:54:11.100 --> 00:54:14.800
so if you get them all in there,
it makes everyone very happy.

00:54:14.800 --> 00:54:15.300
OK.

00:54:15.300 --> 00:54:20.220
Now let's look at
carbon b to the oxygen.

00:54:20.220 --> 00:54:22.830
It's also a single
bond, so sigma.

00:54:22.830 --> 00:54:26.730
We know that carbon b is C2sp 3.

00:54:26.730 --> 00:54:30.990
The oxygen here is
also going to be sp 3

00:54:30.990 --> 00:54:35.820
because it has two bonded atoms
and two sets of lone pairs.

00:54:35.820 --> 00:54:36.390
OK.

00:54:36.390 --> 00:54:37.882
One more clicker.

00:54:57.421 --> 00:54:57.920
All right.

00:54:57.920 --> 00:54:58.827
10 more seconds.

00:55:13.440 --> 00:55:14.010
Great.

00:55:14.010 --> 00:55:16.130
Yup.

00:55:16.130 --> 00:55:20.090
So that is correct and if we
take a look at that over here,

00:55:20.090 --> 00:55:25.670
we have carbon d, it has bonded
to three things so it's sp 2

00:55:25.670 --> 00:55:29.430
and the oxygen is bonded to
two atoms and two lone pairs

00:55:29.430 --> 00:55:32.510
so it's sp 3.

00:55:32.510 --> 00:55:37.610
We can keep going and finish
up between d and c now,

00:55:37.610 --> 00:55:41.810
we have-- oops, sorry,
d and c up here,

00:55:41.810 --> 00:55:46.790
we have d which is 2sp 2
bonded to three things,

00:55:46.790 --> 00:55:52.040
c has bonded to four
things, it's C2sp 3.

00:55:52.040 --> 00:55:57.800
And then finally, d to
e, we have two bonds.

00:55:57.800 --> 00:56:02.030
We have a sigma bond so
that's between our two--

00:56:02.030 --> 00:56:04.820
these two carbons here
are hybridized orbitals

00:56:04.820 --> 00:56:08.450
and again, it's 2sp 2, 2sp 2.

00:56:08.450 --> 00:56:13.040
And it's a double bond so we
have one sigma and one pi bond

00:56:13.040 --> 00:56:18.290
and the pi bond is between
non-hybridized orbitals,

00:56:18.290 --> 00:56:25.160
so it's C2py, C2py or
you could have used x,

00:56:25.160 --> 00:56:27.270
I don't really care about that.

00:56:27.270 --> 00:56:28.070
All right.

00:56:28.070 --> 00:56:28.790
Good practice.

00:56:28.790 --> 00:56:30.710
I think you're getting
the hang of this.

00:56:30.710 --> 00:56:33.530
Again, there will be
more practice problems

00:56:33.530 --> 00:56:38.240
on hybridization posted today
to get you ready for the exam

00:56:38.240 --> 00:56:40.850
and also to figure
out these bonds.

00:56:40.850 --> 00:56:42.500
Once you get the
hang of this, it's

00:56:42.500 --> 00:56:46.870
really pretty trivial and
good points for an exam.