Other Periodic Table Trends

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Language: en

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In the last video we talked
about ionization energy, or

00:00:03.690 --> 00:00:05.925
the energy required to
remove an electron.

00:00:05.925 --> 00:00:10.190
And we saw the general trend
in the periodic table, that

00:00:10.190 --> 00:00:12.310
when you're in the bottom
left-hand side close to

00:00:12.310 --> 00:00:15.590
cesium, cesium really wants
to give up electrons.

00:00:15.590 --> 00:00:16.820
It's a big atom.

00:00:16.820 --> 00:00:19.360
It only has one extra electron
in its sixth shell.

00:00:19.360 --> 00:00:20.870
It can just give it up,
and then it'll have

00:00:20.870 --> 00:00:22.190
five complete shells.

00:00:22.190 --> 00:00:24.250
So it really wants to give it
away, so it requires very

00:00:24.250 --> 00:00:27.040
little energy to ionize.

00:00:27.040 --> 00:00:31.840
On the complete other side of
the spectrum, helium requires

00:00:31.840 --> 00:00:33.220
a lot of energy to ionize.

00:00:33.220 --> 00:00:34.170
It's very happy.

00:00:34.170 --> 00:00:36.850
I has a full shell at
the first shell.

00:00:36.850 --> 00:00:37.990
It's a very small atom.

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The electrons are very
close to the protons.

00:00:39.860 --> 00:00:43.920
So the coulomb force is
super-duper-duper strong.

00:00:43.920 --> 00:00:46.260
So it takes a lot of energy
to remove that incremental

00:00:46.260 --> 00:00:47.270
electron, and we learned that.

00:00:47.270 --> 00:00:49.240
And the one thing I want to
cover before moving on to

00:00:49.240 --> 00:00:52.260
other types of trends or
properties amongst the

00:00:52.260 --> 00:00:55.395
different atoms is the idea of
a second ionization energy.

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And I want to do this because
sometimes it's covered on some

00:01:05.080 --> 00:01:08.280
chemistry exams or some
chemistry standardized tests.

00:01:08.280 --> 00:01:11.810
And it's just the idea that
ionization energy is the

00:01:11.810 --> 00:01:15.700
energy required to remove the
first electron, to go from a

00:01:15.700 --> 00:01:20.450
neutral state to popping
one electron off of it.

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The second ionization energy is,
then, the energy required

00:01:24.350 --> 00:01:26.720
to remove the very
next electron.

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And the reason why this is
interesting, is sometimes

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they'll say, OK, what elements
have a very high second

00:01:32.510 --> 00:01:34.100
ionization energy?

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And your temptation would be,
OK, high ionization energy,

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that also probably means high
second ionization energy.

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And that might be true.

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For example, neon has a very
high ionization energy, It

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really wants to keep that 10th
electron, because it fills out

00:01:49.310 --> 00:01:51.090
the second shell.

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And then, of course, even if you
were able to remove that

00:01:53.900 --> 00:01:58.300
electron, to remove the ninth
electron, when now its

00:01:58.300 --> 00:01:59.950
configuration looks a
lot like fluorine,

00:01:59.950 --> 00:02:00.950
that's still very difficult.

00:02:00.950 --> 00:02:02.620
So you'd say its second
ionization energy

00:02:02.620 --> 00:02:04.370
is still very high.

00:02:04.370 --> 00:02:10.419
But if you think about it, the
elements with the highest

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second ionization energies are
going to be some of the

00:02:13.710 --> 00:02:16.340
elements with the lowest
ionization energy.

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So, think about it.

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And that might be kind
of confusing.

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Lithium, for example.

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Very low ionization energy.

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It's got that extra electron.

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It just wants to give it away.

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But once it gives it away,
it's in a very stable

00:02:31.080 --> 00:02:32.490
situation, Then its electron

00:02:32.490 --> 00:02:34.580
configuration looks like helium.

00:02:34.580 --> 00:02:36.730
So to remove that second
electron is

00:02:36.730 --> 00:02:38.760
super-duper-duper difficult.

00:02:38.760 --> 00:02:41.950
So lithium has a very high
second ionization energy.

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And so you might run into a
question where they're like,

00:02:44.660 --> 00:02:48.240
which of these elements has the
biggest difference between

00:02:48.240 --> 00:02:51.610
their ionization energy and
their second ionization

00:02:51.610 --> 00:02:53.940
energy, where their second
ionization energy is higher

00:02:53.940 --> 00:02:55.490
than their ionization energy.

00:02:55.490 --> 00:02:57.840
And lithium, or anything in
group one, that would be true,

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because as soon as you remove
one electron, its electron

00:03:01.040 --> 00:03:03.540
configuration becomes super
stable, so removing that

00:03:03.540 --> 00:03:06.320
second one is super-duper
difficult.

00:03:06.320 --> 00:03:08.120
And you also see this
in this chart.

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This is, of course, the first
ionization energies.

00:03:10.820 --> 00:03:13.050
But let's say, the case
with lithium, you

00:03:13.050 --> 00:03:14.020
removed that electron.

00:03:14.020 --> 00:03:14.790
It was very easy.

00:03:14.790 --> 00:03:17.640
You only needed five electron
volts to do it.

00:03:17.640 --> 00:03:20.170
But then your configuration
looks a lot like helium.

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So that second ionization energy
is going to look a lot

00:03:22.210 --> 00:03:24.330
like helium's first
ionization energy.

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Anyway, I don't want to
confuse you too much.

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But that's an interesting point
that might pop up every

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now and then.

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Now another property, which is
in a lot of ways, in my mind,

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related is the idea of
electronegativity.

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The concept came up
by Linus Pauling.

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I always remember him.

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He was a famous chemist. What
I always remember is that he

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was famous for being convinced
that Vitamin C was kind of the

00:03:54.180 --> 00:03:55.540
key to living forever.

00:03:55.540 --> 00:03:57.780
And he would take huge
doses of Vitamin C.

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I should probably read
up on that again.

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I don't want to spread lies
about Linus Pauling.

00:04:01.310 --> 00:04:02.920
But I remember reading that
when I was in high school.

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But anyway, he came up with the
idea of electronegativity.

00:04:05.620 --> 00:04:09.360
And the idea is that when two
atoms form covalent bonds--

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and I haven't taught you what a
covalent bond is, and I was

00:04:13.860 --> 00:04:18.769
planning on doing that in a
couple of videos from now--

00:04:18.769 --> 00:04:20.910
but the idea of a covalent
bond is really just atoms

00:04:20.910 --> 00:04:21.790
sharing electrons.

00:04:21.790 --> 00:04:22.780
Let me draw that out.

00:04:22.780 --> 00:04:28.000
So if I have oxygen, oxygen
looks something like this.

00:04:28.000 --> 00:04:29.010
I could draw it like that.

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I could also draw oxygen like
this, just because I'm going

00:04:33.310 --> 00:04:35.350
to use these extra electrons
to bond.

00:04:35.350 --> 00:04:39.540
And if you take oxygen like
that and you add it to two

00:04:39.540 --> 00:04:42.300
hydrogens-- hydrogen
has one electron--

00:04:42.300 --> 00:04:43.560
what's going to happen?

00:04:43.560 --> 00:04:46.440
You might not know yet, if you
haven't seen a covalent bond.

00:04:46.440 --> 00:04:49.040
But the atoms will actually
share electrons.

00:04:49.040 --> 00:04:51.960
So this oxygen, you put
it in the center.

00:04:51.960 --> 00:04:54.706
You have these, over here.

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Let me draw it like that.

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The electrons from oxygen
I'll do in green.

00:05:00.660 --> 00:05:04.740
And then hydrogen, I'll just
do it in this orange color.

00:05:04.740 --> 00:05:06.640
So we have two of
these hydrogens.

00:05:06.640 --> 00:05:09.940
So one hydrogen will be there.

00:05:09.940 --> 00:05:13.180
And then the other hydrogen
will be there.

00:05:13.180 --> 00:05:14.620
Now what just happened?

00:05:14.620 --> 00:05:19.310
Well if this hydrogen can
pretend that both of these

00:05:19.310 --> 00:05:21.290
electrons, it has to kind
of share this green

00:05:21.290 --> 00:05:22.310
one with the oxygen.

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And the deal is, hey, I share
the green one and you let me

00:05:25.850 --> 00:05:27.710
borrow the green one, and I'll
let you borrow the orange one,

00:05:27.710 --> 00:05:30.410
we both can kind of feel like
we have a stable electron

00:05:30.410 --> 00:05:31.420
configuration.

00:05:31.420 --> 00:05:34.460
Hydrogen feels good because
the one s-shell

00:05:34.460 --> 00:05:35.790
is completely filled.

00:05:35.790 --> 00:05:40.420
Oxygen fills great because
it's valence shell is

00:05:40.420 --> 00:05:42.840
completely filled with
eight electrons, two

00:05:42.840 --> 00:05:43.570
of which are borrowed.

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So it feels great.

00:05:44.340 --> 00:05:47.200
This is a covalent
bond, where the

00:05:47.200 --> 00:05:49.580
atoms are sharing electrons.

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And so this sometimes will
be drawn like this.

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Oxygen.

00:05:53.320 --> 00:05:55.415
Those are the extra electron
pairs of oxygen.

00:05:55.415 --> 00:05:57.220
And they'll just draw
a line like that.

00:06:00.240 --> 00:06:02.650
And that line implicitly is
saying, look, there's two

00:06:02.650 --> 00:06:04.310
atoms on either end.

00:06:04.310 --> 00:06:08.240
There's the oxygen
electron there.

00:06:08.240 --> 00:06:10.660
And then you have the hydrogen
electron there.

00:06:10.660 --> 00:06:11.790
And they're kind of shared.

00:06:11.790 --> 00:06:13.320
These two things mean
the same thing.

00:06:13.320 --> 00:06:16.100
But that line just means
a covalent bond.

00:06:16.100 --> 00:06:19.700
Now my whole point behind
talking about covalent bonds a

00:06:19.700 --> 00:06:22.890
little prematurely is so
that I can touch on

00:06:22.890 --> 00:06:24.140
electronegativity.

00:06:24.140 --> 00:06:28.230
And the idea that Linus Pauling
came up with is that

00:06:28.230 --> 00:06:32.160
in these covalent bonds, the
sharing is not equal.

00:06:32.160 --> 00:06:35.400
That some of the atoms
will hog the

00:06:35.400 --> 00:06:36.970
electrons a little more.

00:06:36.970 --> 00:06:39.330
So in this case, oxygen.

00:06:39.330 --> 00:06:41.720
We learned about oxygen.

00:06:41.720 --> 00:06:43.470
Oxygen is way over here.

00:06:43.470 --> 00:06:47.080
It loves to grab electrons.

00:06:47.080 --> 00:06:49.840
It has a very high ionization
energy.

00:06:49.840 --> 00:06:52.780
It's only two away from having
an electron configuration

00:06:52.780 --> 00:06:55.560
similar to neon and being
super-duper happy.

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So oxygen loves electrons.

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Hydrogen is a little
bit here or there.

00:06:59.350 --> 00:07:01.420
It could gain an electron
and then it'll

00:07:01.420 --> 00:07:04.320
have a stable 1s orbital.

00:07:04.320 --> 00:07:06.470
Or it could lose an electron and
it will essentially just

00:07:06.470 --> 00:07:07.780
turn into a positive ion.

00:07:07.780 --> 00:07:08.700
It can go either way.

00:07:08.700 --> 00:07:12.810
So it's a little bit more
ambivalent about what happens

00:07:12.810 --> 00:07:13.760
relative to the electrons.

00:07:13.760 --> 00:07:16.030
But oxygen really wants
the electrons so

00:07:16.030 --> 00:07:18.300
that it can get completed.

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So in this relationship between
oxygen and hydrogen,

00:07:21.880 --> 00:07:24.950
oxygen is more electronegative.

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It's more electronegative, which
means it kind of hogs

00:07:28.090 --> 00:07:29.700
the electrons a little
bit more.

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So if you were to draw this
relationship here, it might

00:07:33.740 --> 00:07:37.660
look something-- If you were
to draw this bond.

00:07:37.660 --> 00:07:39.480
This is all abstract.

00:07:39.480 --> 00:07:41.590
Maybe you would draw
it a little bit

00:07:41.590 --> 00:07:42.770
heavier on that side.

00:07:42.770 --> 00:07:45.380
And this is not really at
all a convention, but I

00:07:45.380 --> 00:07:46.250
just made that up.

00:07:46.250 --> 00:07:50.630
Or if you just drew the hydrogen
and the oxygen part

00:07:50.630 --> 00:07:53.680
of it, maybe the electrons
spend most of their time

00:07:53.680 --> 00:07:56.120
around-- this is a probability
distribution-- and less of

00:07:56.120 --> 00:07:57.790
their time around hydrogen.

00:07:57.790 --> 00:08:00.720
And that would be true for
the other hydrogen.

00:08:00.720 --> 00:08:02.600
They spend less of their time
around the hydrogen and a lot

00:08:02.600 --> 00:08:04.570
more of their time around
the oxygen.

00:08:04.570 --> 00:08:07.590
The idea of electronegativity is
just that one atom is going

00:08:07.590 --> 00:08:12.670
to hog the electrons more when
you form a covalent bond.

00:08:12.670 --> 00:08:16.740
Now if we wanted to figure out
the trend of electronegativity

00:08:16.740 --> 00:08:20.870
on the periodic table, what do
you think's going to happen?

00:08:20.870 --> 00:08:23.390
Which elements are likely
to hog electrons?

00:08:23.390 --> 00:08:25.050
Well, the ones that
love electrons.

00:08:25.050 --> 00:08:26.330
The ones that it's
very hard to take

00:08:26.330 --> 00:08:27.450
electrons away from them.

00:08:27.450 --> 00:08:35.039
The ones that are super-close
to completing a full eight

00:08:35.039 --> 00:08:37.480
valence electrons in their
outermost shell.

00:08:37.480 --> 00:08:39.280
So the most electronegative
atoms are

00:08:39.280 --> 00:08:41.760
going to be right here.

00:08:41.760 --> 00:08:43.549
They're going to be the
halogens, especially the

00:08:43.549 --> 00:08:47.240
fluorine, because the small ones
want the electrons even

00:08:47.240 --> 00:08:48.400
more because they're
a small atom.

00:08:48.400 --> 00:08:50.670
The electrons are going to get
closer to the nucleus.

00:08:50.670 --> 00:08:54.320
And the reason why I'm not
talking about the noble gases

00:08:54.320 --> 00:08:57.300
here is because these don't
form covalent bonds.

00:08:57.300 --> 00:08:59.150
They're always happy.

00:08:59.150 --> 00:09:00.850
They're all these inert gases.

00:09:00.850 --> 00:09:02.995
Inert just means that they
don't do anything.

00:09:02.995 --> 00:09:04.920
A similar word is inertia.

00:09:04.920 --> 00:09:08.570
Inertia means the tendency to
want to stay at rest, not do

00:09:08.570 --> 00:09:10.600
anything, or stay in motion,
but I won't go

00:09:10.600 --> 00:09:11.450
into that too much.

00:09:11.450 --> 00:09:12.240
But these are inert.

00:09:12.240 --> 00:09:13.020
They don't do anything.

00:09:13.020 --> 00:09:14.510
So these guys react.

00:09:14.510 --> 00:09:17.180
They form covalent
bonds up here.

00:09:17.180 --> 00:09:21.170
And when they form covalent
bonds, they hog the atoms.

00:09:21.170 --> 00:09:25.240
Likewise, when these guys down
here form covalent bonds,

00:09:25.240 --> 00:09:29.000
they're like, you know what,
you can have the atoms. I

00:09:29.000 --> 00:09:29.640
don't need them.

00:09:29.640 --> 00:09:31.500
I'm actually happier without
them altogether.

00:09:31.500 --> 00:09:33.330
In fact, sometimes these
guys actually just

00:09:33.330 --> 00:09:34.620
give away the atom.

00:09:34.620 --> 00:09:36.340
They don't even form
a covalent bond.

00:09:36.340 --> 00:09:37.490
It's called an ionic bond.

00:09:37.490 --> 00:09:39.320
We'll talk about that
in the next video.

00:09:39.320 --> 00:09:44.620
But as you can see, the trend
is the same as it is for

00:09:44.620 --> 00:09:46.180
ionization energy.

00:09:46.180 --> 00:09:48.010
These guys, a lot of
energy required

00:09:48.010 --> 00:09:48.970
to remove an electron.

00:09:48.970 --> 00:09:50.730
That's because they
love electrons.

00:09:50.730 --> 00:09:52.890
So these guys are also
very electronegative.

00:09:52.890 --> 00:09:55.930
They're going to hog the
electrons in a covalent bond.

00:09:55.930 --> 00:09:58.620
These guys, very low
ionization energy.

00:09:58.620 --> 00:10:01.060
Very easy to take an electron
away from them.

00:10:01.060 --> 00:10:05.650
And that's why they have very
low electronegativity.

00:10:05.650 --> 00:10:09.480
They're very unlikely to hog
an electron in a bond.

00:10:09.480 --> 00:10:13.050
Now the other trend that some
people sometimes talk about is

00:10:13.050 --> 00:10:15.095
the metallic nature
of an element.

00:10:22.150 --> 00:10:26.680
And so, there's a lot of things
that, in my mind, I

00:10:26.680 --> 00:10:28.700
imagine when someone talks
about metallic nature, I

00:10:28.700 --> 00:10:31.230
imagine it should conduct
electricity, it should be

00:10:31.230 --> 00:10:33.980
shiny, it should be malleable.

00:10:33.980 --> 00:10:36.240
I can bend it without
it cracking.

00:10:36.240 --> 00:10:37.840
That's how I imagine
metallic nature.

00:10:37.840 --> 00:10:39.560
But when people talk about it
in chemistry, they're really

00:10:39.560 --> 00:10:41.470
just talking about
a willingness

00:10:41.470 --> 00:10:43.270
to give away electrons.

00:10:43.270 --> 00:10:44.140
That's metallic nature.

00:10:44.140 --> 00:10:45.600
And that is important.

00:10:45.600 --> 00:10:47.430
If you talk about something
that's going to conduct

00:10:47.430 --> 00:10:52.320
electricity or be malleable or
have this sea of electrons

00:10:52.320 --> 00:10:55.280
available that the
atoms can sit in.

00:10:55.280 --> 00:10:56.890
But the same trend.

00:10:56.890 --> 00:11:00.810
Which atoms are very likely
to give away electrons?

00:11:00.810 --> 00:11:03.290
Well, the bottom left, right?

00:11:03.290 --> 00:11:06.300
As you go down, the atom gets
bigger, so the electrons are

00:11:06.300 --> 00:11:07.850
further away from the nucleus.

00:11:07.850 --> 00:11:14.400
So the coulomb force is weaker,
so those electrons are

00:11:14.400 --> 00:11:15.810
more weakly bound.

00:11:15.810 --> 00:11:19.080
And also, if you just have one
extra electron here or two

00:11:19.080 --> 00:11:21.162
extra electrons there in your
outermost shell, you're just

00:11:21.162 --> 00:11:24.420
like, hey, let me get rid of
them and then I'll have a

00:11:24.420 --> 00:11:27.030
complete outer shell.

00:11:27.030 --> 00:11:28.880
So these guys want to
give away electrons.

00:11:28.880 --> 00:11:31.290
So they have a very high
metallic nature.

00:11:31.290 --> 00:11:34.450
These guys want to
keep electrons.

00:11:34.450 --> 00:11:35.560
And they want to take more.

00:11:35.560 --> 00:11:37.460
So they have a very low
metallic nature.

00:11:37.460 --> 00:11:41.150
In fact these are completely
non-metallic in any way.

00:11:41.150 --> 00:11:44.680
And if you were to say, within a
group, the trend-- I mean, I

00:11:44.680 --> 00:11:47.290
did the diagonal, but that's in
general true-- is that the

00:11:47.290 --> 00:11:52.960
further you go down a group,
the size of the atom is

00:11:52.960 --> 00:11:55.340
increasing and the outer
electrons are

00:11:55.340 --> 00:11:56.630
further from the nucleus.

00:11:56.630 --> 00:12:00.850
So the electron force is going
to be weaker-- or the coulomb

00:12:00.850 --> 00:12:01.690
force is going to be weaker.

00:12:01.690 --> 00:12:04.060
So you're more likely to
give away electrons.

00:12:04.060 --> 00:12:06.990
So your metallic nature will
increase as you go down.

00:12:06.990 --> 00:12:09.230
And your metallic nature will
increase as you go to the

00:12:09.230 --> 00:12:12.365
left, because when you only have
a couple of electrons in

00:12:12.365 --> 00:12:13.800
your outermost shell, you
want to give them away.

00:12:13.800 --> 00:12:16.780
So metallic nature, it goes
in the opposite direction.

00:12:16.780 --> 00:12:17.660
It goes like that.

00:12:17.660 --> 00:12:18.890
But for the same reason.

00:12:18.890 --> 00:12:20.440
These guys love to
hog electrons.

00:12:20.440 --> 00:12:23.680
These guys love to
give them away.

00:12:23.680 --> 00:12:23.910
Right?

00:12:23.910 --> 00:12:27.070
So ionization energy increased
to the top right.

00:12:27.070 --> 00:12:30.010
Electronegativity increased
to the top right.

00:12:30.010 --> 00:12:32.920
Metallic nature increased
to the bottom left.

00:12:32.920 --> 00:12:35.625
The last trend we could talk
about is just atomic radius.

00:12:38.252 --> 00:12:43.070
And there's a lot of different
ways to actually measure this.

00:12:43.070 --> 00:12:45.890
And there's no one best way,
because obviously, we already

00:12:45.890 --> 00:12:48.140
talked about it, an atom doesn't
have a fixed radius.

00:12:48.140 --> 00:12:50.830
The electron could show up
pretty much anywhere.

00:12:50.830 --> 00:12:53.360
So you could just kind of
do a hard boundary.

00:12:53.360 --> 00:12:55.695
OK, 90% chance of finding
the electron.

00:12:55.695 --> 00:12:58.120
That's your sphere
of the atom.

00:12:58.120 --> 00:13:01.890
Or you could say, OK, if this
atom bonds with another atom,

00:13:01.890 --> 00:13:04.240
what is half the distance
between the two nucleuses.

00:13:04.240 --> 00:13:04.470
Right?

00:13:04.470 --> 00:13:08.060
If you make a bond like that.

00:13:08.060 --> 00:13:10.325
This is the distance between the
two nucleuses and then you

00:13:10.325 --> 00:13:12.690
can say the atomic
radius is that.

00:13:12.690 --> 00:13:13.580
So there's a lot of ways.

00:13:13.580 --> 00:13:14.770
But I think you get
the general idea.

00:13:14.770 --> 00:13:17.210
It's just the size
of the atom.

00:13:17.210 --> 00:13:19.950
And you could already imagine
that as you go down any one

00:13:19.950 --> 00:13:23.370
group, the size of the
atom increases.

00:13:23.370 --> 00:13:25.850
You're adding on more and
more energy levels,

00:13:25.850 --> 00:13:27.300
more and more shells.

00:13:27.300 --> 00:13:29.290
The atom is just getting
larger and larger.

00:13:29.290 --> 00:13:32.350
In fact, we've used that as an
argument as to why, as you go

00:13:32.350 --> 00:13:35.190
down, ionization energy
goes down, or

00:13:35.190 --> 00:13:36.340
electronegativity goes down.

00:13:36.340 --> 00:13:43.550
So the atoms become larger
as you go down.

00:13:43.550 --> 00:13:45.290
Now, the one thing that might
be a little un-intuitive is

00:13:45.290 --> 00:13:47.770
what happens as you
go to the right?

00:13:47.770 --> 00:13:51.070
You're adding electrons as you
go to the right, but you're

00:13:51.070 --> 00:13:53.010
adding them all in the
same shell, right?

00:13:53.010 --> 00:13:55.610
So if this is the nucleus, right
there, and you're in

00:13:55.610 --> 00:13:58.200
some shell, some
orbital shell.

00:13:58.200 --> 00:13:59.560
And obviously, they're
not all spheres.

00:13:59.560 --> 00:14:01.470
But let's say you're in
some orbital shell.

00:14:01.470 --> 00:14:04.900
As you go to the right in a
period, you just keep adding

00:14:04.900 --> 00:14:07.430
electrons to that shell.

00:14:07.430 --> 00:14:07.640
Right?

00:14:07.640 --> 00:14:10.710
This is a super-gross
oversimplification.

00:14:10.710 --> 00:14:13.180
And as you go to the right,
you have more

00:14:13.180 --> 00:14:15.040
protons in the nucleus.

00:14:15.040 --> 00:14:18.680
So this is only getting more and
more positively charged.

00:14:18.680 --> 00:14:23.800
So what happens is that these
electrons get pulled inwards.

00:14:23.800 --> 00:14:25.170
They get pulled inwards.

00:14:25.170 --> 00:14:27.150
So as you move to
the right on the

00:14:27.150 --> 00:14:29.670
periodic table, size decreases.

00:14:39.450 --> 00:14:40.870
And then you say, OK, but
what about when you

00:14:40.870 --> 00:14:42.900
go to the next period?

00:14:42.900 --> 00:14:44.210
You're getting more
protons there.

00:14:44.210 --> 00:14:45.280
Won't that decrease?

00:14:45.280 --> 00:14:46.120
You are.

00:14:46.120 --> 00:14:48.330
But at the same time, you're now
adding the electrons in a

00:14:48.330 --> 00:14:50.740
new shell that's further
from them.

00:14:50.740 --> 00:14:54.390
So it gets larger when you
go to the new period.

00:14:54.390 --> 00:14:59.310
So electron size, as
you go down, large.

00:14:59.310 --> 00:15:03.405
And as you go to the left,
you get larger.

00:15:03.405 --> 00:15:10.000
So electron size goes from the
bottom right to the top left.

00:15:10.000 --> 00:15:13.940
Although in general, the things
that are in a lower

00:15:13.940 --> 00:15:17.420
period will have a larger size
than most things in a higher

00:15:17.420 --> 00:15:20.120
period, regardless of
what group it's in.

00:15:20.120 --> 00:15:24.950
But the general trend within a
group, the higher the number,

00:15:24.950 --> 00:15:26.340
the larger the atom.

00:15:26.340 --> 00:15:29.780
Within a period, the more
protons you have,

00:15:29.780 --> 00:15:31.690
the smaller the atom.

00:15:31.690 --> 00:15:34.080
Anyway, I hope you found
those interesting.

00:15:34.080 --> 00:15:37.390
In the next few videos we'll
start with bonding.


Periodic Table Trends: Ionization Energy

WEBVTT
Kind: captions
Language: en

00:00:00.000 --> 00:00:03.220
I think we're now ready to
start talking about some

00:00:03.220 --> 00:00:05.410
general trends in the
periodic table.

00:00:05.410 --> 00:00:07.680
And the first one that normally
comes up in a lot of

00:00:07.680 --> 00:00:11.210
first-year chemistry classes,
and it even shows up on some

00:00:11.210 --> 00:00:13.940
chemistry standardized
tests, is the notion

00:00:13.940 --> 00:00:15.745
of ionization energy.

00:00:21.490 --> 00:00:24.590
And what this is, is essentially
the energy

00:00:24.590 --> 00:00:29.290
required to remove an electron
from the neutral

00:00:29.290 --> 00:00:30.580
version of that atom.

00:00:30.580 --> 00:00:31.950
So let's see.

00:00:31.950 --> 00:00:41.380
Energy to remove an electron.

00:00:41.380 --> 00:00:44.080
And just in case you haven't
been exposed to the idea of

00:00:44.080 --> 00:00:46.940
what an ion is, I guess this is
a good time to explain it.

00:00:46.940 --> 00:00:48.730
And then this will make sense.

00:00:48.730 --> 00:00:53.760
So an ion is essentially any
atom or molecule -- and we'll

00:00:53.760 --> 00:00:54.800
talk about molecules.

00:00:54.800 --> 00:00:57.470
Molecules are just combinations
or groups of

00:00:57.470 --> 00:00:59.750
atoms that are all bonded
together in some way.

00:00:59.750 --> 00:01:02.990
And we'll talk about bonding
in a few videos from now.

00:01:02.990 --> 00:01:08.750
But it's an atom or a molecule
in which the protons don't

00:01:08.750 --> 00:01:10.446
equal the electrons.

00:01:10.446 --> 00:01:13.140
And if the protons don't equal
the electrons, then you have

00:01:13.140 --> 00:01:13.950
some charge.

00:01:13.950 --> 00:01:17.250
If you have more protons than
electrons, you have a positive

00:01:17.250 --> 00:01:18.890
charge, right?

00:01:18.890 --> 00:01:22.520
So let's say if you
have hydrogen.

00:01:22.520 --> 00:01:23.530
Let's say you have hydrogen.

00:01:23.530 --> 00:01:24.720
Normally it's neutral, right?

00:01:24.720 --> 00:01:25.850
It has no charge.

00:01:25.850 --> 00:01:28.220
But let's say you were to remove
an electron from it.

00:01:28.220 --> 00:01:30.940
So now you have hydrogen
plus an electron.

00:01:30.940 --> 00:01:33.820
Hydrogen only has one
electron outside.

00:01:33.820 --> 00:01:36.760
So now it just has a proton on
the inside, no electrons on

00:01:36.760 --> 00:01:37.190
the outside.

00:01:37.190 --> 00:01:39.360
So now it has a plus
one charge.

00:01:39.360 --> 00:01:41.190
We could write a minus
one there.

00:01:41.190 --> 00:01:43.860
And now, what we've done in
this, I guess we could say,

00:01:43.860 --> 00:01:48.235
this procedure or this reaction
is, we've removed

00:01:48.235 --> 00:01:49.970
we've ionized hydrogen.

00:01:49.970 --> 00:01:52.410
We've removed an electron.

00:01:52.410 --> 00:01:57.160
And in this case, this type of
ion that hydrogen is, where

00:01:57.160 --> 00:01:59.070
your protons are greater than
your electrons, and this is

00:01:59.070 --> 00:02:00.840
just a nice word to know.

00:02:00.840 --> 00:02:03.020
This is called a cation.

00:02:03.020 --> 00:02:06.610
A cation is an ion with
a positive charge.

00:02:06.610 --> 00:02:09.550
Now you just as easily could
have a situation where you

00:02:09.550 --> 00:02:13.075
have a, let's say -- I don't
know, let me take an element

00:02:13.075 --> 00:02:14.430
-- let's say we start
with chlorine.

00:02:17.200 --> 00:02:18.810
Cl, right?

00:02:18.810 --> 00:02:21.880
In a stable form in has seven
valence electrons.

00:02:21.880 --> 00:02:24.870
Why don't we add an
electron to it.

00:02:24.870 --> 00:02:28.500
And now this will actually
be pretty stable.

00:02:28.500 --> 00:02:31.640
It will have eight valence
electrons, but it'll have a

00:02:31.640 --> 00:02:32.840
negative charge.

00:02:32.840 --> 00:02:36.490
So this, right here, this
is a negative ion.

00:02:36.490 --> 00:02:40.200
And that's known as an anion.

00:02:40.200 --> 00:02:41.220
Anion.

00:02:41.220 --> 00:02:45.770
The way I remember it is, in
a lot of words, a means the

00:02:45.770 --> 00:02:47.750
opposite or a negation.

00:02:47.750 --> 00:02:48.550
Right?

00:02:48.550 --> 00:02:49.800
The a prefix.

00:02:49.800 --> 00:02:53.930
So a, anion, means
a negative ion.

00:02:53.930 --> 00:02:55.910
And then, obviously, cation
is the other.

00:02:55.910 --> 00:02:58.920
But ionization energy, it really
should maybe be called

00:02:58.920 --> 00:03:01.860
cationization energy, because
it's the energy required to

00:03:01.860 --> 00:03:05.310
remove an electron, not remove
or add an electron.

00:03:05.310 --> 00:03:07.670
So it's really the energy
required to turn something

00:03:07.670 --> 00:03:11.140
into a cation.

00:03:11.140 --> 00:03:13.810
So we've already discussed the
periodic table, and we'll get

00:03:13.810 --> 00:03:15.840
to this chart in a second.

00:03:15.840 --> 00:03:19.400
But just based on what we
already know, which elements

00:03:19.400 --> 00:03:22.060
will it be harder to remove an
electron from and which ones

00:03:22.060 --> 00:03:23.740
will it be easier?

00:03:23.740 --> 00:03:25.720
We already talked about -- let's
start with group one,

00:03:25.720 --> 00:03:27.610
just because it is group one.

00:03:27.610 --> 00:03:29.200
Group one is right here.

00:03:29.200 --> 00:03:31.900
And we'll start especially
with the alkali metals.

00:03:31.900 --> 00:03:34.340
We can put hydrogen
aside for now.

00:03:34.340 --> 00:03:36.960
But all of these guys we've
talked about a lot.

00:03:36.960 --> 00:03:39.890
In order for them to get to
the magic number eight in

00:03:39.890 --> 00:03:42.820
their outermost shell, the
easiest way for them to do it

00:03:42.820 --> 00:03:46.520
is just to get rid of that one
valence electron they have in

00:03:46.520 --> 00:03:49.200
their outermost shell.

00:03:49.200 --> 00:03:52.090
Let's say potassium,
right there.

00:03:52.090 --> 00:03:57.210
Potassium has one valence
electron in its fourth shell.

00:03:57.210 --> 00:03:58.850
If it just got rid of it,
then it has eight

00:03:58.850 --> 00:03:59.640
in its third shell.

00:03:59.640 --> 00:04:02.440
Then it looks a lot like argon
from an electron configuration

00:04:02.440 --> 00:04:03.960
point of view, which
would be nice.

00:04:03.960 --> 00:04:07.736
So these guys really want
to give away electrons.

00:04:07.736 --> 00:04:13.160
So it requires very little
energy to ionize them or to

00:04:13.160 --> 00:04:15.390
cationize them, to take
away their electron.

00:04:15.390 --> 00:04:19.130
So this is low ionization
energy.

00:04:19.130 --> 00:04:22.200
And I think you see where
this is going.

00:04:22.200 --> 00:04:24.640
What about these guys?

00:04:24.640 --> 00:04:26.980
What about neon?

00:04:26.980 --> 00:04:30.370
How hard is it to remove
an electron from neon.

00:04:30.370 --> 00:04:32.780
Well neon is completely
satisfied.

00:04:32.780 --> 00:04:34.930
It doesn't want to even deal
with any of this reaction

00:04:34.930 --> 00:04:36.540
business and bonding business.

00:04:36.540 --> 00:04:38.070
It's like, you know what?

00:04:38.070 --> 00:04:41.050
I've achieved happiness
in life.

00:04:41.050 --> 00:04:42.380
Don't mess with my electron.

00:04:42.380 --> 00:04:44.880
So it really doesn't want to
give away its electrons.

00:04:44.880 --> 00:04:48.360
Neon, or krypton, or argon, or
any of these noble gases.

00:04:48.360 --> 00:04:51.460
So to remove an electron from
one of these guys requires a

00:04:51.460 --> 00:04:53.190
lot of energy.

00:04:53.190 --> 00:04:55.910
So this is a high ionization
energy.

00:04:55.910 --> 00:04:58.730
So in general, as you go from
left to right across the

00:04:58.730 --> 00:05:00.230
periodic table, it goes
from low to high.

00:05:00.230 --> 00:05:02.300
And some people memorize this,
but you really don't have to

00:05:02.300 --> 00:05:02.930
memorize it.

00:05:02.930 --> 00:05:06.190
You just say, look, these guys
have one extra electron that

00:05:06.190 --> 00:05:07.270
they're always trying
to get rid of.

00:05:07.270 --> 00:05:08.520
These guys have two.

00:05:11.350 --> 00:05:12.920
Ideally they'd want to
get rid of, maybe,

00:05:12.920 --> 00:05:14.190
both of their electrons.

00:05:14.190 --> 00:05:17.570
But the first electron doesn't
want to jump off as much as

00:05:17.570 --> 00:05:19.590
the first electron here, because
the first electron

00:05:19.590 --> 00:05:21.780
here, you get rid of it, you
immediately get to the super

00:05:21.780 --> 00:05:23.060
stable state.

00:05:23.060 --> 00:05:25.470
And that trend just becomes
more and more true.

00:05:25.470 --> 00:05:28.750
This guy, definitely, under no
circumstances wants to give

00:05:28.750 --> 00:05:29.970
away an electron.

00:05:29.970 --> 00:05:32.770
This guy is so close to being
like neon that he definitely

00:05:32.770 --> 00:05:34.240
doesn't want to go a
step backwards and

00:05:34.240 --> 00:05:35.600
look more like oxygen.

00:05:35.600 --> 00:05:37.430
So he doesn't want to get
rid of an electron.

00:05:37.430 --> 00:05:38.640
So the trend is pretty clear.

00:05:38.640 --> 00:05:40.490
Anytime you're confused about
the trend, just look at the

00:05:40.490 --> 00:05:41.300
extreme cases.

00:05:41.300 --> 00:05:43.390
This guy wants to give
away electrons.

00:05:43.390 --> 00:05:45.560
This guy wants to
get electrons.

00:05:45.560 --> 00:05:48.680
So if you say, what's the energy
required to take away

00:05:48.680 --> 00:05:48.900
an electron?

00:05:48.900 --> 00:05:50.730
Well this guy's almost going
to give it to you.

00:05:50.730 --> 00:05:53.540
While this guy's going to be
very hard, especially neon, to

00:05:53.540 --> 00:05:55.260
take away an electron.

00:05:55.260 --> 00:05:57.350
Now what happens
as you go down?

00:05:57.350 --> 00:06:00.590
As you go down in this
direction, let's say you go

00:06:00.590 --> 00:06:02.110
along a group, right?

00:06:02.110 --> 00:06:05.200
We already established that
these alkali metals like to

00:06:05.200 --> 00:06:06.560
give away electrons.

00:06:06.560 --> 00:06:09.970
But as you go down,
the electron cloud

00:06:09.970 --> 00:06:11.290
gets bigger and bigger.

00:06:11.290 --> 00:06:14.750
And you could say this 55th
electron -- there's 55

00:06:14.750 --> 00:06:17.600
protons, there's also in a
neutral cesium atom, there's

00:06:17.600 --> 00:06:22.020
also 55 electrons -- that 55th
electron is a lot further away

00:06:22.020 --> 00:06:27.170
from the nucleus of this atom
than the third electron is in

00:06:27.170 --> 00:06:28.810
the case of lithium.

00:06:28.810 --> 00:06:32.300
So this, the 55th electron, not
only does it want to be

00:06:32.300 --> 00:06:35.270
given away, but it has even
a weaker attraction to the

00:06:35.270 --> 00:06:37.980
nucleus than the third electron
does in lithium.

00:06:37.980 --> 00:06:40.820
So because you're getting larger
and larger as you go

00:06:40.820 --> 00:06:43.250
down a group, and the electrons
are getting further

00:06:43.250 --> 00:06:47.320
and further away from the
nucleus, this guy wants to

00:06:47.320 --> 00:06:51.570
give away his electrons even
more than lithium does.

00:06:51.570 --> 00:06:52.220
Right?

00:06:52.220 --> 00:06:57.580
So ionization energy decreases
as you go down.

00:06:57.580 --> 00:07:01.440
Even though xenon really wants
to keep his electrons, he's a

00:07:01.440 --> 00:07:05.050
little bit more willing to give
them away than neon is.

00:07:05.050 --> 00:07:05.400
Right?

00:07:05.400 --> 00:07:11.700
So in general, the ionization
energy, or the energy required

00:07:11.700 --> 00:07:18.780
to ionize an atom, will
increase as you go up.

00:07:18.780 --> 00:07:19.090
Right?

00:07:19.090 --> 00:07:21.330
And if you ever forget it, don't
memorize these things.

00:07:21.330 --> 00:07:23.470
Because that might be useful
for just one test, but then

00:07:23.470 --> 00:07:26.990
later in life when you're 42
and someone asks you, hey,

00:07:26.990 --> 00:07:30.710
what has a higher ionization
energy, cesium or fluorine?

00:07:30.710 --> 00:07:31.940
You might have forgotten it.

00:07:31.940 --> 00:07:33.890
But then if you look at a
periodic table, you'd say, you

00:07:33.890 --> 00:07:37.250
know, cesium has this one
electron that it's just dying

00:07:37.250 --> 00:07:37.910
to give away.

00:07:37.910 --> 00:07:42.400
It's super far away
from the nucleus.

00:07:42.400 --> 00:07:45.340
That 55th electron just really
wants to leave. While

00:07:45.340 --> 00:07:50.170
fluorine, that ninth electron
just needs one more electron.

00:07:50.170 --> 00:07:51.630
Well let's say neon.

00:07:51.630 --> 00:07:53.510
Neon is super happy.

00:07:53.510 --> 00:07:56.250
All the electrons are in the
stable configuration.

00:07:56.250 --> 00:07:57.860
They're close to the nucleus.

00:07:57.860 --> 00:07:59.320
There's a lot of attraction
with the

00:07:59.320 --> 00:08:00.470
protons in the nucleus.

00:08:00.470 --> 00:08:03.550
They definitely don't want to
give away their electrons.

00:08:03.550 --> 00:08:05.430
So if you talk about the energy
required to remove

00:08:05.430 --> 00:08:08.870
them, very low energy
at cesium, very

00:08:08.870 --> 00:08:11.320
high energy at helium.

00:08:11.320 --> 00:08:12.210
So that's the trend.

00:08:12.210 --> 00:08:17.520
And this is just, this trend
we'll see often, this is your

00:08:17.520 --> 00:08:18.530
willingness to give electrons.

00:08:18.530 --> 00:08:21.880
And this is how much you want to
hog electrons or keep them

00:08:21.880 --> 00:08:23.470
to yourself.

00:08:23.470 --> 00:08:26.320
And this right here, this is
actually -- I got this off

00:08:26.320 --> 00:08:28.840
Wikipedia -- this
is the actual,

00:08:28.840 --> 00:08:30.600
measured ionization energies.

00:08:30.600 --> 00:08:33.020
And people looked at
patterns like this.

00:08:33.020 --> 00:08:34.799
I'm not sure if they actually
looked at the ionization

00:08:34.799 --> 00:08:36.520
energy, but they looked at
patterns like this, and this

00:08:36.520 --> 00:08:38.450
is actually where they came up
with the periodic table.

00:08:38.450 --> 00:08:44.110
Because they said, look, as we
increment up the number of

00:08:44.110 --> 00:08:47.100
protons that we have in an atom,
and likewise, the number

00:08:47.100 --> 00:08:51.020
of electrons, we see these
repeated patterns, or these

00:08:51.020 --> 00:08:52.940
periods, in the elements.

00:08:52.940 --> 00:08:55.710
So this is hydrogen.

00:08:55.710 --> 00:08:59.210
So hydrogen's ionization
energy is around 13 1/2

00:08:59.210 --> 00:09:00.990
electron volts.

00:09:00.990 --> 00:09:01.670
Right?

00:09:01.670 --> 00:09:02.920
Which is a unit of energy.

00:09:02.920 --> 00:09:05.530
It can be converted into
joules, if you like.

00:09:05.530 --> 00:09:07.310
But then all of a sudden, helium
is a lot more stable.

00:09:07.310 --> 00:09:11.980
It takes almost double the
energy to remove that second

00:09:11.980 --> 00:09:14.090
electron from helium because
it's so stable.

00:09:14.090 --> 00:09:16.660
But as soon as you do that, as
soon as you go from helium,

00:09:16.660 --> 00:09:21.960
this point right here, that
point right here is lithium.

00:09:21.960 --> 00:09:22.330
Right?

00:09:22.330 --> 00:09:23.990
Lithium is atomic
number of three.

00:09:23.990 --> 00:09:25.350
Let me put that in.

00:09:25.350 --> 00:09:26.480
This is lithium.

00:09:26.480 --> 00:09:29.760
All of a sudden, to remove an
electron from lithium it only

00:09:29.760 --> 00:09:31.480
requires five electron volts.

00:09:31.480 --> 00:09:35.450
So less than half of what it
required for hydrogen.

00:09:35.450 --> 00:09:37.990
Then as you go to the right
of the periodic table, the

00:09:37.990 --> 00:09:40.340
ionization energy keeps
increasing.

00:09:40.340 --> 00:09:42.240
These little divots
are interesting.

00:09:42.240 --> 00:09:44.770
We could talk about that, maybe,
in a future video.

00:09:44.770 --> 00:09:48.940
But the ionization energy
increases all the way to neon.

00:09:48.940 --> 00:09:51.020
And then you get to neon and
then you add one more-- see,

00:09:51.020 --> 00:09:53.850
neon is a noble gas, it's
completely happy -- then you

00:09:53.850 --> 00:09:55.910
add one more electron and
you get to sodium.

00:09:55.910 --> 00:09:58.520
And you say, oh, now sodium,
it's really easy to take away

00:09:58.520 --> 00:09:59.046
that electron.

00:09:59.046 --> 00:10:01.370
And the ionization
energy drops.

00:10:01.370 --> 00:10:04.390
Not only did it drop,
but here it dropped

00:10:04.390 --> 00:10:05.520
slightly below lithium.

00:10:05.520 --> 00:10:07.570
So you see this general trend.

00:10:07.570 --> 00:10:10.600
So these are the noble
gases right here.

00:10:10.600 --> 00:10:13.250
Let me make sure you can see
them all in the video screen.

00:10:13.250 --> 00:10:14.300
Helium.

00:10:14.300 --> 00:10:17.100
Very hard to remove that
eighth electron.

00:10:17.100 --> 00:10:17.600
Neon.

00:10:17.600 --> 00:10:19.300
It's very hard, but a little
easier than helium.

00:10:19.300 --> 00:10:21.430
And that's because neon is
a little bit bigger.

00:10:21.430 --> 00:10:24.170
The electrons are a little bit
further away from the nucleus.

00:10:24.170 --> 00:10:25.100
Argon.

00:10:25.100 --> 00:10:27.390
Same pattern, but it's
actually interesting.

00:10:27.390 --> 00:10:30.830
Argon is actually not that
different than hydrogen.

00:10:30.830 --> 00:10:31.520
Krypton.

00:10:31.520 --> 00:10:32.010
Same thing.

00:10:32.010 --> 00:10:33.850
It's hard to remove
that electron.

00:10:33.850 --> 00:10:37.050
But it's actually no harder to
remove the electron on krypton

00:10:37.050 --> 00:10:38.080
than on hydrogen.

00:10:38.080 --> 00:10:38.830
And xenon.

00:10:38.830 --> 00:10:44.260
And you go all the
way out to radon.

00:10:44.260 --> 00:10:46.680
And you can see, you know, why
is the distance between these

00:10:46.680 --> 00:10:47.180
increasing?

00:10:47.180 --> 00:10:50.930
Well if you remember the
periodic table, all of a

00:10:50.930 --> 00:10:53.600
sudden when you go after argon,
then you have all of

00:10:53.600 --> 00:10:55.780
the d-block elements
that go in.

00:10:55.780 --> 00:10:58.490
So after you get to
argon, notice.

00:10:58.490 --> 00:11:02.470
This is where you only had
s- and p-block elements.

00:11:02.470 --> 00:11:04.560
Now all of a sudden the d-block
elements show up.

00:11:04.560 --> 00:11:10.120
So you have more subshells
to fill up.

00:11:10.120 --> 00:11:13.590
And now all of a sudden, before
you get to radon,

00:11:13.590 --> 00:11:16.480
you're starting to fill
out the f-block, too.

00:11:16.480 --> 00:11:18.320
And that's why that distance
is increasing, because you

00:11:18.320 --> 00:11:20.230
have to also fill out
the f elements.

00:11:20.230 --> 00:11:21.820
But the general trends
that we just

00:11:21.820 --> 00:11:24.210
discussed, they apply here.

00:11:24.210 --> 00:11:27.530
That as you go to the right
along the periodic table, it

00:11:27.530 --> 00:11:29.670
becomes harder and harder to
remove an electron because

00:11:29.670 --> 00:11:31.430
everyone wants to get to
the magic number eight.

00:11:31.430 --> 00:11:33.800
And it's very hard to remove
them from a noble gas.

00:11:33.800 --> 00:11:36.190
But then as you go one more
above that, this guy would

00:11:36.190 --> 00:11:39.500
love to give away his electron
and get back to a

00:11:39.500 --> 00:11:41.320
configuration like neon.

00:11:41.320 --> 00:11:45.380
And then the other trend is,
as you go down a group-- in

00:11:45.380 --> 00:11:49.670
this case, these are the
noble gases-- the

00:11:49.670 --> 00:11:51.140
ionization energy decreases.

00:11:51.140 --> 00:11:55.630
And that's because the overall
radius of the atom increases,

00:11:55.630 --> 00:12:00.670
so the valence electrons in
radon are a little bit less

00:12:00.670 --> 00:12:04.520
strongly attracted than the
valence electrons in helium.

00:12:04.520 --> 00:12:07.700
Anyway, I think that's it
for ionization energy.

00:12:07.700 --> 00:12:09.100
I'll continue this
in another video.

00:12:09.100 --> 00:12:10.540
We'll talk about metallic
character and

00:12:10.540 --> 00:12:11.790
electronegativity.


Valence Electrons

WEBVTT
Kind: captions
Language: en

00:00:00.940 --> 00:00:04.350
So far, we've learned a little
bit about determining electron

00:00:04.350 --> 00:00:05.210
configurations.

00:00:05.210 --> 00:00:08.590
Let's see if we can use that
information to group elements

00:00:08.590 --> 00:00:12.440
on the periodic table and then
guess as to what they might do

00:00:12.440 --> 00:00:14.130
when they react with
other elements.

00:00:14.130 --> 00:00:16.890
So let's just figure out the
electron configurations of a

00:00:16.890 --> 00:00:18.680
couple of elements just for
a little bit of practice.

00:00:18.680 --> 00:00:20.920
So, lithium, right there.

00:00:20.920 --> 00:00:22.630
What does it look like?

00:00:22.630 --> 00:00:25.970
Lithium's electron
configuration.

00:00:25.970 --> 00:00:29.670
You get the first
shell, is 1s2.

00:00:29.670 --> 00:00:31.200
Two electrons there.

00:00:31.200 --> 00:00:34.840
And then you have 2s1.

00:00:34.840 --> 00:00:37.270
And sometimes, just to be quick,
to get the notation, is

00:00:37.270 --> 00:00:40.280
you can imagine lithium's
electron configuration is the

00:00:40.280 --> 00:00:43.970
exact same thing as helium's
electron configuration-- this

00:00:43.970 --> 00:00:47.070
is helium's electron
configuration-- plus the 2s1.

00:00:47.070 --> 00:00:49.940
This could have also been
written as-- do that in light

00:00:49.940 --> 00:00:56.690
blue-- could also have been
written as helium, 2s1.

00:00:56.690 --> 00:00:58.810
Which essentially means that
lithium's electron

00:00:58.810 --> 00:01:01.330
configuration is exactly what
you would have written for

00:01:01.330 --> 00:01:03.360
helium's electron configuration,
and then you'd

00:01:03.360 --> 00:01:04.390
have written 2s1.

00:01:04.390 --> 00:01:05.960
You could do that a
bunch of times.

00:01:05.960 --> 00:01:07.720
Let's say if we wanted to
figure out the electron

00:01:07.720 --> 00:01:11.980
configuration of iron.

00:01:11.980 --> 00:01:14.180
Instead of going through the
whole thing, you know, it's

00:01:14.180 --> 00:01:18.950
1s2, and then it's
2s2, and 2p6.

00:01:18.950 --> 00:01:20.360
Instead of doing that whole
thing, you could just say, OK,

00:01:20.360 --> 00:01:23.130
iron has the same electron
configuration.

00:01:23.130 --> 00:01:26.180
So you could say iron's electron
configuration is the

00:01:26.180 --> 00:01:32.375
same thing as argon's electron
configuration.

00:01:32.375 --> 00:01:36.140
So I'll just put argon
in brackets.

00:01:36.140 --> 00:01:38.750
And then you get 4s2.

00:01:43.200 --> 00:01:48.280
And then you have one, two,
three, four, five, six.

00:01:48.280 --> 00:01:49.750
So d6.

00:01:49.750 --> 00:01:53.630
And we learned that when you're
in the d subshell, or

00:01:53.630 --> 00:01:56.740
when you're in the d-block of
the periodic table, you are

00:01:56.740 --> 00:02:01.350
actually backfilling
the previous shell.

00:02:01.350 --> 00:02:04.830
So when we're in the fourth
period, in the d-block, we're

00:02:04.830 --> 00:02:06.850
backfilling the third shell.

00:02:06.850 --> 00:02:09.930
So 3d6.

00:02:09.930 --> 00:02:11.870
And someone had asked-- and
this is an interesting

00:02:11.870 --> 00:02:13.740
question-- why does
it do that?

00:02:13.740 --> 00:02:15.230
Why does it not just continue?

00:02:15.230 --> 00:02:17.890
Why doesn't it fill the
fourth d shell?

00:02:17.890 --> 00:02:20.790
And the way I think about it--
and this is all intuition, and

00:02:20.790 --> 00:02:23.510
things at the atomic level
really start to become, on

00:02:23.510 --> 00:02:25.880
some levels, non-intuitive-- but
the way I think about is

00:02:25.880 --> 00:02:30.090
as the atom grows larger and
larger, there are more spaces

00:02:30.090 --> 00:02:31.510
between the previous orbitals.

00:02:31.510 --> 00:02:36.560
For example, this is just
how I visualize it.

00:02:36.560 --> 00:02:39.430
If my first shell
looks like this.

00:02:39.430 --> 00:02:41.260
Let's say the s looks
like this.

00:02:41.260 --> 00:02:44.440
And then, if I just cut it out,
let's say the p's look

00:02:44.440 --> 00:02:45.690
like something like this.

00:02:49.000 --> 00:02:51.810
This is maybe the
second shell.

00:02:51.810 --> 00:02:53.060
The p's look like this.

00:02:53.060 --> 00:02:55.210
And then the next place an
electron might want to be

00:02:55.210 --> 00:02:59.150
might be in the third
shell, right?

00:02:59.150 --> 00:03:03.900
So the third shell would
be like this.

00:03:03.900 --> 00:03:07.970
And then you fill out
the third p shell.

00:03:07.970 --> 00:03:09.290
This is just an intuition.

00:03:09.290 --> 00:03:10.830
This isn't exactly what an
electron would look like.

00:03:10.830 --> 00:03:13.540
Maybe the third p shell would
look something like that.

00:03:16.860 --> 00:03:19.470
Look something like that.

00:03:19.470 --> 00:03:21.910
And then look something
like that.

00:03:21.910 --> 00:03:24.020
And then you're in
the fourth shell.

00:03:24.020 --> 00:03:27.520
So you're doing the
fourth shell.

00:03:27.520 --> 00:03:31.650
The s subshell might look
something like that.

00:03:31.650 --> 00:03:35.230
And then instead of immediately
starting the next

00:03:35.230 --> 00:03:39.310
p shell, you're in
the d-block now.

00:03:39.310 --> 00:03:44.830
So this is-- let me just
write some labels-- 4s.

00:03:44.830 --> 00:03:46.920
This is 3s.

00:03:46.920 --> 00:03:50.020
This is 3p.

00:03:50.020 --> 00:03:52.500
This is 2p.

00:03:52.500 --> 00:03:53.930
This is 2s.

00:03:56.770 --> 00:03:58.650
And then 1s is inside of 2s.

00:03:58.650 --> 00:03:59.980
So you don't have to worry
about that too much.

00:03:59.980 --> 00:04:04.390
But my intuition behind why the
d orbital gets backfilled

00:04:04.390 --> 00:04:07.350
is because now, as the atom gets
larger and larger, you

00:04:07.350 --> 00:04:09.830
have these spaces in between
the previous orbital.

00:04:09.830 --> 00:04:18.790
So now, after filling the 4s
subshell, or the 4s orbital--

00:04:18.790 --> 00:04:23.690
so this is 4s here-- out here,
we go back and we fill in the

00:04:23.690 --> 00:04:24.960
3d orbital.

00:04:24.960 --> 00:04:26.980
So we're going back and
we're filling these

00:04:26.980 --> 00:04:30.450
spaces right here.

00:04:30.450 --> 00:04:32.580
So this is a lower energy
state than this.

00:04:32.580 --> 00:04:36.730
It takes more energy to cram an
electron back into the 3d

00:04:36.730 --> 00:04:38.530
shell, back there.

00:04:38.530 --> 00:04:42.180
But then once you do that, now
you're ready to then go to the

00:04:42.180 --> 00:04:48.120
4p shell, which might look
something like this.

00:04:48.120 --> 00:04:51.610
So an electron would rather go
to another shell, which is the

00:04:51.610 --> 00:04:56.870
fourth shell, rather than
backfill the 3d shells.

00:04:56.870 --> 00:04:58.950
But once it fills out the fourth
shell, it fills in

00:04:58.950 --> 00:04:59.915
those spaces in between.

00:04:59.915 --> 00:05:02.690
And as the electron gets bigger
and bigger, there's

00:05:02.690 --> 00:05:04.260
more and more spaces
in between.

00:05:04.260 --> 00:05:06.940
So eventually, when the electron
gets big enough,

00:05:06.940 --> 00:05:08.860
there's going to be spaces
between the d shells, and

00:05:08.860 --> 00:05:12.930
that's where the d orbitals
and that's where the f

00:05:12.930 --> 00:05:13.990
orbitals will go.

00:05:13.990 --> 00:05:15.610
That's my intuition behind
its working.

00:05:15.610 --> 00:05:18.740
And obviously, when we're
dealing at the atomic scale,

00:05:18.740 --> 00:05:21.050
as far as I'm concerned, that's
the best that I can do.

00:05:21.050 --> 00:05:21.670
But fair enough.

00:05:21.670 --> 00:05:23.220
That's not what I want to do
here, but that was a good

00:05:23.220 --> 00:05:27.580
question, as to why do you go
and backfill the third shell

00:05:27.580 --> 00:05:29.290
when we're in the
fourth period?

00:05:29.290 --> 00:05:29.750
Fair enough.

00:05:29.750 --> 00:05:34.500
This is an easy way to write
iron's electron configuration.

00:05:34.500 --> 00:05:37.710
The reason why I'm doing all of
this is to figure out how

00:05:37.710 --> 00:05:39.890
many electrons you have in
the outermost shell.

00:05:39.890 --> 00:05:44.630
In the case of lithium, you
have one electron in your

00:05:44.630 --> 00:05:45.680
outermost shell, right?

00:05:45.680 --> 00:05:47.860
This is your outermost
shell right here.

00:05:47.860 --> 00:05:49.490
You have one electron.

00:05:49.490 --> 00:05:51.740
And you could have done the
same thing right there.

00:05:51.740 --> 00:05:53.580
In the case of iron, how
many electrons in

00:05:53.580 --> 00:05:55.000
the outermost shell?

00:05:55.000 --> 00:05:57.950
Remember, the outermost shell
is the period you're in.

00:05:57.950 --> 00:06:00.570
And this is the outermost
shell.

00:06:00.570 --> 00:06:03.260
So even though these are higher
energy electrons-- it

00:06:03.260 --> 00:06:07.550
took more energy to backfill
those into the lower energy

00:06:07.550 --> 00:06:11.630
shell-- it's these that are on
the outside energy shell, the

00:06:11.630 --> 00:06:13.670
fourth shell, that are
going to be the

00:06:13.670 --> 00:06:14.450
ones that are reacting.

00:06:14.450 --> 00:06:15.220
And how many are there?

00:06:15.220 --> 00:06:17.590
There are two.

00:06:17.590 --> 00:06:18.920
And this is an important
thing.

00:06:18.920 --> 00:06:21.410
So there's two here.

00:06:21.410 --> 00:06:22.710
There's two on the outside
shell here.

00:06:22.710 --> 00:06:24.940
And actually, there's going to
be two for any of these in

00:06:24.940 --> 00:06:25.610
pink right here.

00:06:25.610 --> 00:06:28.880
Any of the ones in the d-block,
what happens?

00:06:28.880 --> 00:06:30.730
You fill whatever period
you're in.

00:06:30.730 --> 00:06:33.310
Let's say that you're
in period five here.

00:06:33.310 --> 00:06:33.670
Right?

00:06:33.670 --> 00:06:35.850
You're going to have 5s1.

00:06:35.850 --> 00:06:37.240
5s2.

00:06:37.240 --> 00:06:39.050
And then you're going to go back
and you're going to fill

00:06:39.050 --> 00:06:40.490
the 4d shell.

00:06:40.490 --> 00:06:41.190
Right?

00:06:41.190 --> 00:06:43.240
But in terms of how many
electrons you have on the

00:06:43.240 --> 00:06:46.200
outside shell, in this case the
fifth shell, you are going

00:06:46.200 --> 00:06:47.660
to have two electrons.

00:06:47.660 --> 00:06:51.060
So all of these are going to
have to electrons in their

00:06:51.060 --> 00:06:52.310
outermost shell.

00:06:54.650 --> 00:06:56.832
In the case of these, the
outermost electrons are going

00:06:56.832 --> 00:06:58.750
to be 4s2, right?

00:06:58.750 --> 00:07:01.210
Because then you go back and
fill the 3d, but the outer

00:07:01.210 --> 00:07:03.000
ones are 4s2.

00:07:03.000 --> 00:07:04.640
So this one also has
two electrons in

00:07:04.640 --> 00:07:05.930
its outermost shell.

00:07:05.930 --> 00:07:08.540
How many does this group have?

00:07:08.540 --> 00:07:10.940
And I've just used a word that
I don't know if I've defined

00:07:10.940 --> 00:07:15.030
before, but the group are the
columns in the periodic table.

00:07:15.030 --> 00:07:18.590
And as you can see, they all
have patterns to them.

00:07:18.590 --> 00:07:21.990
Everything in this first group
has one electron in its

00:07:21.990 --> 00:07:23.770
outermost shell.

00:07:23.770 --> 00:07:26.090
If you don't believe me,
look at hydrogen.

00:07:26.090 --> 00:07:28.510
Hydrogen's electron
configuration is 1s1.

00:07:28.510 --> 00:07:30.925
Its outermost shell is 1s.

00:07:30.925 --> 00:07:33.620
It has one electron there.

00:07:33.620 --> 00:07:33.960
Right?

00:07:33.960 --> 00:07:35.190
And that's true for
all of these.

00:07:35.190 --> 00:07:36.985
All of these guys have
two electrons in

00:07:36.985 --> 00:07:38.480
their outermost shell.

00:07:38.480 --> 00:07:40.930
These guys have those
same two electrons.

00:07:40.930 --> 00:07:42.780
We can view it that way, in
their outermost shell, but

00:07:42.780 --> 00:07:44.530
then they go and backfill
the d shell.

00:07:44.530 --> 00:07:45.610
But in terms of their outermost

00:07:45.610 --> 00:07:48.460
shell, only two electrons.

00:07:48.460 --> 00:07:52.620
Than once you fill the d-block,
or you go backfill,

00:07:52.620 --> 00:07:55.670
in the case of the fourth
period, you go and backfill

00:07:55.670 --> 00:07:58.570
the third d sub-orbital.

00:07:58.570 --> 00:08:01.660
Then you go back to filling
the fourth shell again.

00:08:01.660 --> 00:08:03.860
Now the p block, right?

00:08:03.860 --> 00:08:09.540
So this one's going to
have three electrons

00:08:09.540 --> 00:08:11.010
in its outside orbital.

00:08:11.010 --> 00:08:14.060
Or you could say three
valence electrons.

00:08:14.060 --> 00:08:19.710
This is four, five, six,
seven, and eight.

00:08:19.710 --> 00:08:22.620
Let me do one more, just in
case you don't believe me.

00:08:22.620 --> 00:08:28.270
What's the electron
configuration for Sn.

00:08:28.270 --> 00:08:30.920
This is, what, selenium?

00:08:30.920 --> 00:08:31.740
I'm not even sure.

00:08:31.740 --> 00:08:32.690
But let's say Sn.

00:08:32.690 --> 00:08:34.210
What's the electron
configuration?

00:08:34.210 --> 00:08:35.620
It's going to have
the same electron

00:08:35.620 --> 00:08:38.640
configuration as krypton.

00:08:38.640 --> 00:08:40.409
Yes, that element is krypton.

00:08:40.409 --> 00:08:42.789
There is such an element.

00:08:42.789 --> 00:08:44.070
So it will have the
same electron

00:08:44.070 --> 00:08:45.520
configuration as krypton.

00:08:45.520 --> 00:08:47.120
So I could have figured
out krypton's electron

00:08:47.120 --> 00:08:48.920
configuration just by going
through the whole periodic

00:08:48.920 --> 00:08:51.020
table, but this is just a
faster way of doing it.

00:08:51.020 --> 00:08:53.420
Same thing as krypton,
and then it has 5s2.

00:08:58.460 --> 00:09:00.940
Then it goes back and backfills
the d-block.

00:09:00.940 --> 00:09:02.470
So then there's 10 there.

00:09:02.470 --> 00:09:07.130
So 4d10.

00:09:07.130 --> 00:09:09.380
And then it starts filling
up the p-block in

00:09:09.380 --> 00:09:10.390
the fifth shell again.

00:09:10.390 --> 00:09:11.640
So 5p2.

00:09:14.630 --> 00:09:16.930
So how many valence electrons
does it have?

00:09:16.930 --> 00:09:19.310
Valence electrons,
or electrons in

00:09:19.310 --> 00:09:21.440
the outermost shell?

00:09:21.440 --> 00:09:22.800
Well, what's the outermost
shell?

00:09:22.800 --> 00:09:24.250
It's the fifth shell.

00:09:24.250 --> 00:09:29.440
So these and these.

00:09:29.440 --> 00:09:31.750
These electrons have a higher
energy state than that.

00:09:31.750 --> 00:09:33.960
It took a little bit more energy
to cram them back into

00:09:33.960 --> 00:09:35.800
that previous shell than
it took to put

00:09:35.800 --> 00:09:37.310
these on the s orbital.

00:09:37.310 --> 00:09:39.630
But if you talk about the
electrons that will react, and

00:09:39.630 --> 00:09:41.830
that's why I'm emphasizing
these, these are the electrons

00:09:41.830 --> 00:09:47.130
that are going to react with
other atoms. Or sometimes with

00:09:47.130 --> 00:09:49.840
just other electrons, even.

00:09:49.840 --> 00:09:52.460
This one has four outside
electrons.

00:09:52.460 --> 00:09:53.920
And you see that right there.

00:09:53.920 --> 00:09:55.700
Four outside electrons.

00:09:55.700 --> 00:09:58.900
And since the outside electrons,
for the most part,

00:09:58.900 --> 00:10:03.130
are the ones that you're going
to care about, there's a-- I

00:10:03.130 --> 00:10:05.750
guess you could say, a notation
where you only draw

00:10:05.750 --> 00:10:07.130
the outermost electrons.

00:10:07.130 --> 00:10:10.820
So, let's say, for hydrogen, you
could write it like this.

00:10:10.820 --> 00:10:14.150
Where you're only drawing the
outermost, valence electrons.

00:10:14.150 --> 00:10:16.070
Valence electrons are just
the outermost electrons.

00:10:16.070 --> 00:10:17.540
You could write it like that.

00:10:17.540 --> 00:10:19.040
You could write it like that.

00:10:19.040 --> 00:10:21.150
But this says, hey, I just
have one outside

00:10:21.150 --> 00:10:22.980
electron for hydrogen.

00:10:22.980 --> 00:10:25.380
If I wanted to draw
it for iron?

00:10:25.380 --> 00:10:26.900
Iron, right here?

00:10:26.900 --> 00:10:27.520
How would I do that?

00:10:27.520 --> 00:10:31.170
I have two electrons in my
outermost shell, so iron I

00:10:31.170 --> 00:10:33.890
could just do like this.

00:10:33.890 --> 00:10:36.130
And electrons, they
tend to be paired.

00:10:36.130 --> 00:10:40.050
So if I have, let's say I wanted
to take the example of,

00:10:40.050 --> 00:10:42.810
if this is Sn, this
is selenium.

00:10:42.810 --> 00:10:44.270
Let me do carbon.

00:10:44.270 --> 00:10:47.840
Carbon, I have four electrons
in my outermost shell.

00:10:47.840 --> 00:10:49.470
So carbon I could
write like this.

00:10:54.400 --> 00:10:58.750
Or if I didn't want to pair
them, in theory I could write

00:10:58.750 --> 00:11:01.220
them like that as well.

00:11:01.220 --> 00:11:04.010
And now they're ready to react
with other things.

00:11:04.010 --> 00:11:06.800
Now what does this tell me
about, you know, this one has

00:11:06.800 --> 00:11:09.410
one electron in its
outermost shell.

00:11:09.410 --> 00:11:13.390
These blue, these noble gases--
and we'll talk a

00:11:13.390 --> 00:11:16.690
little bit about them in a
second-- have eight electrons

00:11:16.690 --> 00:11:17.380
in the outermost shell.

00:11:17.380 --> 00:11:19.560
How does that help me when I'm
actually trying to figure out

00:11:19.560 --> 00:11:21.200
how things react?

00:11:21.200 --> 00:11:25.730
Well, it turns out that all
atoms want to have eight

00:11:25.730 --> 00:11:27.200
electrons in their
outermost shell.

00:11:27.200 --> 00:11:28.660
And that number is important.

00:11:28.660 --> 00:11:30.000
Eight.

00:11:30.000 --> 00:11:34.320
They want to have eight
electrons in

00:11:34.320 --> 00:11:35.870
their outermost shell.

00:11:35.870 --> 00:11:39.230
This is the most stable
configuration for atoms. Or I

00:11:39.230 --> 00:11:43.050
guess you could say, to some
degree, a better energy state

00:11:43.050 --> 00:11:43.980
for the atom.

00:11:43.980 --> 00:11:45.260
And why is it the
number eight?

00:11:45.260 --> 00:11:48.020
Well, that's something
to think about.

00:11:48.020 --> 00:11:49.980
This is another fundamental
number that

00:11:49.980 --> 00:11:51.380
just pops out of nature.

00:11:51.380 --> 00:11:52.610
And I've thought a little
bit about it.

00:11:52.610 --> 00:11:56.400
It must be something about the
atoms in the outermost shell,

00:11:56.400 --> 00:11:58.760
when you have eight, they
resonate well with each other.

00:11:58.760 --> 00:12:02.270
And they somehow don't get
in the way of each other.

00:12:02.270 --> 00:12:03.780
Or don't want to push away
from each other.

00:12:03.780 --> 00:12:04.950
I don't know the
answer to that.

00:12:04.950 --> 00:12:07.280
And frankly, if someone could
really answer the question of

00:12:07.280 --> 00:12:14.790
why eight, exactly why eight,
they would make a good career

00:12:14.790 --> 00:12:17.140
for themselves in physics
or chemistry.

00:12:17.140 --> 00:12:20.580
But through experimentation, it
has been well established

00:12:20.580 --> 00:12:23.260
that atoms want to have
eight electrons in

00:12:23.260 --> 00:12:24.990
their outermost shell.

00:12:24.990 --> 00:12:29.010
So the question is, if you're
dealing with something like,

00:12:29.010 --> 00:12:32.030
let's say you're dealing
with potassium.

00:12:32.030 --> 00:12:32.410
Right?

00:12:32.410 --> 00:12:38.140
Potassium has one electron
in its outermost shell.

00:12:38.140 --> 00:12:46.240
Let's say you have stuff like
chlorine, that has seven

00:12:46.240 --> 00:12:49.100
electrons in its outermost
shell.

00:12:49.100 --> 00:12:50.970
What do you think's going to
happen if you put some

00:12:50.970 --> 00:12:54.850
potassium near some chlorine?

00:12:54.850 --> 00:12:56.360
What's going to happen?

00:12:56.360 --> 00:13:02.560
Well, what's the easiest
way for the chlorine

00:13:02.560 --> 00:13:03.525
to get eight electrons?

00:13:03.525 --> 00:13:05.980
Well it has seven in its
outermost shell.

00:13:05.980 --> 00:13:06.610
What's the easiest way?

00:13:06.610 --> 00:13:10.040
Well, it'll want to gain an
electron really, really badly.

00:13:10.040 --> 00:13:12.290
And what's the easiest way for
potassium to have eight

00:13:12.290 --> 00:13:14.670
electrons in its outermost
shell?

00:13:14.670 --> 00:13:17.860
Well, if it lost that one
electron, then it will have

00:13:17.860 --> 00:13:20.340
eight electrons in its outermost
shell, right?

00:13:20.340 --> 00:13:22.450
Its outermost shell won't be
the fourth shell anymore.

00:13:22.450 --> 00:13:23.700
It'll be the third shell.

00:13:23.700 --> 00:13:25.950
But it'll have eight electrons
in the third shell.

00:13:25.950 --> 00:13:29.820
Its configuration will then look
like argon if it loses

00:13:29.820 --> 00:13:30.900
that one electron.

00:13:30.900 --> 00:13:33.720
So it'll be a more
stable state.

00:13:33.720 --> 00:13:37.690
So if you put sodium in the
presence of chlorine, what's

00:13:37.690 --> 00:13:38.650
going to happen?

00:13:38.650 --> 00:13:42.020
This electron wants to jump off
of sodium real bad so that

00:13:42.020 --> 00:13:43.890
sodium can have eight electrons
in its outermost

00:13:43.890 --> 00:13:47.680
shell, or have an electron
configuration like argon.

00:13:47.680 --> 00:13:50.410
And that electron is going to
jump to chlorine, and then

00:13:50.410 --> 00:13:52.710
chlorine will have eight
electrons in its outermost

00:13:52.710 --> 00:13:54.070
shell, and also have
an electron

00:13:54.070 --> 00:13:56.970
configuration like argon.

00:13:56.970 --> 00:14:01.560
And so, as you can imagine, this
group right here, which

00:14:01.560 --> 00:14:05.030
are called the alkali metals.

00:14:05.030 --> 00:14:06.600
And we'll talk probably
in the next video why

00:14:06.600 --> 00:14:08.230
they're called metals.

00:14:08.230 --> 00:14:09.810
This group here,
alkali metals.

00:14:09.810 --> 00:14:11.630
And they tend to exclude
hydrogen, and

00:14:11.630 --> 00:14:13.110
we'll talk about that.

00:14:13.110 --> 00:14:16.140
These really want to give
away electrons.

00:14:16.140 --> 00:14:18.620
And because of that, they're
highly, highly reactive,

00:14:18.620 --> 00:14:21.050
especially if you put them
in the presence of these

00:14:21.050 --> 00:14:23.050
elements, these yellow elements
right here, which are

00:14:23.050 --> 00:14:24.510
called the halogens.

00:14:24.510 --> 00:14:27.150
These really, really want to
take electrons from other

00:14:27.150 --> 00:14:29.440
things, because they just need
one to get to eight.

00:14:29.440 --> 00:14:31.750
They usually want to give away
electrons, because they just

00:14:31.750 --> 00:14:34.640
have to give away one
to get to eight.

00:14:34.640 --> 00:14:36.790
And the reason why hydrogen,
actually, isn't included is

00:14:36.790 --> 00:14:39.060
because hydrogen doesn't want
to give away its electron as

00:14:39.060 --> 00:14:41.930
bad as these guys.

00:14:41.930 --> 00:14:44.920
This rule that your outermost
shell wants to get to eight,

00:14:44.920 --> 00:14:46.440
that's true for everything
except for

00:14:46.440 --> 00:14:47.790
hydrogen and helium.

00:14:47.790 --> 00:14:50.310
Hydrogen and helium, just
because they have one shell,

00:14:50.310 --> 00:14:52.330
they're happy with just
two electrons.

00:14:52.330 --> 00:14:55.380
And so with hydrogen, sure, it
could lose an electron, but

00:14:55.380 --> 00:14:57.860
could just as easily gain an
electron and be happy, because

00:14:57.860 --> 00:15:00.540
it'll have a full first shell.

00:15:00.540 --> 00:15:04.510
But all of these other ones,
these alkali metals, they want

00:15:04.510 --> 00:15:06.430
to give away electrons
really bad.

00:15:06.430 --> 00:15:09.100
When people in chemistry talk
about metallic nature, they're

00:15:09.100 --> 00:15:11.900
really talking about how
badly something wants

00:15:11.900 --> 00:15:13.720
to give away electrons.

00:15:13.720 --> 00:15:15.260
Anyway, I'm all out
of time now.

00:15:15.260 --> 00:15:17.960
In the next video, we'll
continue discussing the groups

00:15:17.960 --> 00:15:20.620
in the periodic tables
and any trends we can

00:15:20.620 --> 00:15:22.800
ascertain from them.


Groups of the Periodic Table

WEBVTT
Kind: captions
Language: en

00:00:00.840 --> 00:00:04.740
In the last video we talked
about how every atom really

00:00:04.740 --> 00:00:08.280
wants to have eight-- let me
write that down-- eight

00:00:08.280 --> 00:00:11.030
electrons in its outermost
shell.

00:00:11.030 --> 00:00:14.510
This is kind of the most stable
configuration than an

00:00:14.510 --> 00:00:17.740
electron can have. And given
this fact that's been

00:00:17.740 --> 00:00:21.180
determined just by observing
the world, really, we can

00:00:21.180 --> 00:00:24.420
start to figure out what's
likely to happen in different

00:00:24.420 --> 00:00:26.350
groups of the periodic table.

00:00:26.350 --> 00:00:28.820
A group of a periodic table
is just a column of

00:00:28.820 --> 00:00:30.220
the periodic table.

00:00:30.220 --> 00:00:32.479
Like this group, right here, and
actually I'll start with

00:00:32.479 --> 00:00:35.960
this group, because it's
got a special name.

00:00:35.960 --> 00:00:39.160
This group right here is
called the noble gases.

00:00:39.160 --> 00:00:41.860
And what's common when you
go down a group in

00:00:41.860 --> 00:00:42.900
the periodic table?

00:00:42.900 --> 00:00:45.970
What's common about a column
in the periodic table?

00:00:45.970 --> 00:00:50.100
Well, in the last video we saw
that every element in a column

00:00:50.100 --> 00:00:52.700
has the same number of
valence electrons.

00:00:52.700 --> 00:00:55.220
Or it has the same number
of electrons in

00:00:55.220 --> 00:00:56.580
its outermost shell.

00:00:56.580 --> 00:00:58.000
And we figured out
what that was.

00:00:58.000 --> 00:01:01.160
This column, right here, which
we learned were the alkali

00:01:01.160 --> 00:01:05.830
metals, this has one electron
in its outermost shell.

00:01:05.830 --> 00:01:08.530
And I made that one caveat
that hydrogen isn't

00:01:08.530 --> 00:01:10.830
necessarily considered
an alkali metal.

00:01:10.830 --> 00:01:13.230
One, it's usually not
in metal form.

00:01:13.230 --> 00:01:16.320
And it doesn't want to give
away electrons as much as

00:01:16.320 --> 00:01:17.490
other metals do.

00:01:17.490 --> 00:01:21.080
When people talk about
metal-like characteristics of

00:01:21.080 --> 00:01:23.160
an element, they're really
talking about how likely it is

00:01:23.160 --> 00:01:24.640
to give away electron.

00:01:24.640 --> 00:01:26.460
We'll talk about other
characteristics of a metal,

00:01:26.460 --> 00:01:30.020
especially the way that we
perceive metals as being

00:01:30.020 --> 00:01:32.610
shiny, and maybe they conduct
electricity, and see how that

00:01:32.610 --> 00:01:34.060
plays out in the
periodic table.

00:01:34.060 --> 00:01:35.760
But anyway, back to what
I was talking about.

00:01:35.760 --> 00:01:37.610
This column, right here,
this is called the

00:01:37.610 --> 00:01:40.680
alkaline earth metals.

00:01:40.680 --> 00:01:42.420
So this is alkaline earth.

00:01:51.130 --> 00:01:54.340
These all have two atoms
in its outermost shell.

00:01:54.340 --> 00:01:56.450
So remember, everyone wants
to get to eight.

00:01:56.450 --> 00:02:00.070
If these guys wanted to get to
eight by adding electrons,

00:02:00.070 --> 00:02:01.130
they would have a
long way to go.

00:02:01.130 --> 00:02:03.570
This way, we would have to
add seven electrons.

00:02:03.570 --> 00:02:05.850
They would have to add
six electrons.

00:02:05.850 --> 00:02:07.340
And who are they going
to take it from?

00:02:07.340 --> 00:02:09.090
Because these guys don't want to
give away their electrons.

00:02:09.090 --> 00:02:10.860
They're so close to
getting to eight.

00:02:10.860 --> 00:02:12.980
So it's much easier when you're
on the left-hand side

00:02:12.980 --> 00:02:15.350
of the periodic table to
give away electrons.

00:02:15.350 --> 00:02:19.120
In fact, when you only have one
to give away-- especially

00:02:19.120 --> 00:02:22.150
in the case of elements other
than hydrogen-- when you only

00:02:22.150 --> 00:02:24.980
have one to give away, it
really wants to do that.

00:02:24.980 --> 00:02:28.330
And because of that, these
elements right here are very

00:02:28.330 --> 00:02:30.440
seldom found in their
elemental state.

00:02:30.440 --> 00:02:32.900
When I say elemental state, it
means there's nothing but

00:02:32.900 --> 00:02:36.730
lithium there, there's nothing
but sodium there, there's

00:02:36.730 --> 00:02:37.950
nothing but potassium there.

00:02:37.950 --> 00:02:40.610
They're very likely, if you
find this, it's probably

00:02:40.610 --> 00:02:42.530
already reacted with
something.

00:02:42.530 --> 00:02:44.470
Probably with something on
this side of the periodic

00:02:44.470 --> 00:02:46.520
table, because this wants to
give away something really

00:02:46.520 --> 00:02:49.150
bad, this wants to take
something really bad.

00:02:49.150 --> 00:02:51.340
So the reaction will
probably happen.

00:02:51.340 --> 00:02:53.100
These are still reactive.

00:02:53.100 --> 00:02:56.200
The alkaline earth metals are
still reactive, but not as

00:02:56.200 --> 00:02:59.160
reactive as the alkali metals.

00:02:59.160 --> 00:03:02.090
And that's because these guys
are really close to getting to

00:03:02.090 --> 00:03:03.840
the stable magic eight number.

00:03:03.840 --> 00:03:06.210
These guys are a little
bit further away.

00:03:06.210 --> 00:03:12.420
So it takes a little bit more,
I guess you could say, of a

00:03:12.420 --> 00:03:14.670
push for them to
give away two.

00:03:14.670 --> 00:03:16.820
These guys only have
to give away one.

00:03:16.820 --> 00:03:19.485
And then we learned that
this has two in

00:03:19.485 --> 00:03:20.440
its outermost shell.

00:03:20.440 --> 00:03:23.140
And then all of these elements,
which are called the

00:03:23.140 --> 00:03:26.710
transition metals, as you add
electrons, they're just

00:03:26.710 --> 00:03:31.410
backfilling the previous
shell's d subshell.

00:03:31.410 --> 00:03:31.940
Right?

00:03:31.940 --> 00:03:34.920
So their outermost shell
still has two.

00:03:34.920 --> 00:03:36.660
It still has those.

00:03:36.660 --> 00:03:41.300
If this is the fourth period,
all of these elements'

00:03:41.300 --> 00:03:45.460
outermost shell has 4s2.

00:03:45.460 --> 00:03:48.560
And these elements are just
backfilling their 3d

00:03:48.560 --> 00:03:50.720
suborbital.

00:03:50.720 --> 00:03:52.950
Or their 3d subshell.

00:03:52.950 --> 00:03:54.690
These are 2's.

00:03:54.690 --> 00:03:57.400
So these all have two
outermost electrons.

00:03:57.400 --> 00:04:01.190
So all of these, like the
alkaline earth metals, need to

00:04:01.190 --> 00:04:06.320
lose two electrons in order to,
quote-unquote, be happy.

00:04:06.320 --> 00:04:08.410
And the way I think about this,
and this is really just

00:04:08.410 --> 00:04:11.810
a way-- and it maybe it bears
out in physical reality-- is

00:04:11.810 --> 00:04:14.870
that these guys have kind of
a deep bench of electrons.

00:04:14.870 --> 00:04:19.649
That if they are able to shed
some of these valence

00:04:19.649 --> 00:04:25.580
electrons-- so if I write iron
has two valence electrons like

00:04:25.580 --> 00:04:29.890
that-- even if they shed these
electrons, they kind of have a

00:04:29.890 --> 00:04:34.660
reserve of electrons in
the d subshell for

00:04:34.660 --> 00:04:36.420
the previous shell.

00:04:36.420 --> 00:04:40.980
So if it sheds its 4s2
electrons, it still has all

00:04:40.980 --> 00:04:43.740
those 3d electrons that have a
high energy state that can

00:04:43.740 --> 00:04:45.650
maybe kind of replace them.

00:04:45.650 --> 00:04:47.930
And I'll use everything in
quotation marks, because these

00:04:47.930 --> 00:04:50.770
are just ways for me to
visualize things.

00:04:50.770 --> 00:04:55.010
And the reason why I make that
point is because metals are

00:04:55.010 --> 00:04:58.020
just very giving with
their electrons.

00:04:58.020 --> 00:05:00.380
And these guys react.

00:05:00.380 --> 00:05:01.780
They say, hey, take
my electrons.

00:05:01.780 --> 00:05:03.680
These guys say, take these
two electrons.

00:05:03.680 --> 00:05:06.680
And these guys, they start to
say, especially as you fill

00:05:06.680 --> 00:05:09.260
the d subshell, I've got these
two electrons, and not only do

00:05:09.260 --> 00:05:11.420
I have those two electrons,
but I have more electrons

00:05:11.420 --> 00:05:13.520
where-- well almost where--
that came from.

00:05:13.520 --> 00:05:16.050
I have some in reserve
in my d.

00:05:16.050 --> 00:05:18.690
And what happens in these
transition metals, and it

00:05:18.690 --> 00:05:21.470
especially happens in the
metals-- so these are the

00:05:21.470 --> 00:05:24.110
metals right here, and these
don't follow just a group, but

00:05:24.110 --> 00:05:27.960
this is the metals, this color
right here-- is that they have

00:05:27.960 --> 00:05:31.940
so many electrons to hand off,
not only do they have these

00:05:31.940 --> 00:05:35.370
extra there, but they filled
their d subshell, that they

00:05:35.370 --> 00:05:37.660
can kind of, especially when
they're in elemental form, and

00:05:37.660 --> 00:05:39.820
when I say elemental form, this
means that you just have

00:05:39.820 --> 00:05:41.450
a big block of aluminum.

00:05:41.450 --> 00:05:45.700
Aluminum hasn't reacted with
anything like oxygen.

00:05:45.700 --> 00:05:47.500
It's just a bunch of aluminum.

00:05:47.500 --> 00:05:47.810
Right?

00:05:47.810 --> 00:05:49.640
When you have a bunch of
aluminum, what happens is you

00:05:49.640 --> 00:05:51.840
have these metallic bonds where
all of the aluminum

00:05:51.840 --> 00:05:54.550
atoms say, you know what, I have
all these extra, I have

00:05:54.550 --> 00:05:58.525
definitely, in the case of
aluminum, three electrons in

00:05:58.525 --> 00:05:59.470
my outermost shell.

00:05:59.470 --> 00:06:02.840
But I have all of these kind of
backfilled electrons in my

00:06:02.840 --> 00:06:04.040
d suborbital.

00:06:04.040 --> 00:06:06.600
I'm just going to share them
with the other aluminum atoms.

00:06:06.600 --> 00:06:09.170
So you create this sea of
aluminum atoms. And they're

00:06:09.170 --> 00:06:10.430
attracted to each other.

00:06:10.430 --> 00:06:12.750
Or you create this sea of
aluminum electrons.

00:06:12.750 --> 00:06:20.090
So you have a bunch of electrons
sitting in between

00:06:20.090 --> 00:06:22.620
the atoms, and since the atoms
kind of donated these

00:06:22.620 --> 00:06:24.270
electrons, they're attracted
to them.

00:06:24.270 --> 00:06:24.950
Right?

00:06:24.950 --> 00:06:30.030
So the actual atoms-- so this
would be an aluminum plus, and

00:06:30.030 --> 00:06:31.405
maybe we would have donated
three electrons.

00:06:31.405 --> 00:06:33.470
But I'm not being exact here.

00:06:33.470 --> 00:06:35.410
I want to just give you the
sense of how things work.

00:06:35.410 --> 00:06:38.320
And that's why metals conduct
really well, because

00:06:38.320 --> 00:06:41.320
electricity is just a bunch of
electrons moving, and in order

00:06:41.320 --> 00:06:45.460
to have electrons moving, you
have to have surplus electrons

00:06:45.460 --> 00:06:46.330
lying around.

00:06:46.330 --> 00:06:48.480
So elements right around this
area are really good

00:06:48.480 --> 00:06:48.980
conductors.

00:06:48.980 --> 00:06:53.650
In fact, silver is the
best conductor.

00:06:53.650 --> 00:06:57.240
Silver, right here, is the best
conductor on the planet.

00:06:57.240 --> 00:07:01.440
And the reason why that's not
used for our wiring and copper

00:07:01.440 --> 00:07:04.300
is because copper is easier
to find than silver.

00:07:04.300 --> 00:07:06.140
But silver is the
best conductor.

00:07:06.140 --> 00:07:09.340
And the way I think about it
is that these-- once you've

00:07:09.340 --> 00:07:11.010
filled an orbital, that orbital

00:07:11.010 --> 00:07:12.890
becomes somewhat stable.

00:07:12.890 --> 00:07:16.140
So all of these guys have
filled their d orbital.

00:07:16.140 --> 00:07:18.960
While these guys, their d
orbital is not filled.

00:07:18.960 --> 00:07:20.910
So they just have a lot of
surplus electrons that are

00:07:20.910 --> 00:07:21.970
really good for conduction.

00:07:21.970 --> 00:07:24.120
Now, that's just an intuition.

00:07:24.120 --> 00:07:26.000
I haven't done the experiment
to prove that.

00:07:26.000 --> 00:07:28.100
But it'll give you a
sense of why things

00:07:28.100 --> 00:07:29.100
conduct and all of that.

00:07:29.100 --> 00:07:32.370
So these are the transition
metals.

00:07:32.370 --> 00:07:33.870
These are actually considered
the metals.

00:07:33.870 --> 00:07:35.940
But the reason why these are
considered the transition

00:07:35.940 --> 00:07:37.960
metals is because they're
filling the d-block.

00:07:37.960 --> 00:07:40.600
But transition metals kind
of sound like not

00:07:40.600 --> 00:07:41.390
as good as a metal.

00:07:41.390 --> 00:07:44.460
But when I think of metals,
iron is kind of the first

00:07:44.460 --> 00:07:45.610
metal I always think of.

00:07:45.610 --> 00:07:49.020
I definitely think of silver and
copper and gold as metals.

00:07:49.020 --> 00:07:51.270
So to call them transition
metals is a little not fair.

00:07:51.270 --> 00:07:54.120
I don't really consider aluminum
more of a metal than,

00:07:54.120 --> 00:07:55.230
let's say, iron is.

00:07:55.230 --> 00:07:58.140
But in chemistry classification
world, aluminum

00:07:58.140 --> 00:08:00.370
is more of a metal.

00:08:00.370 --> 00:08:01.880
These elements right here.

00:08:01.880 --> 00:08:04.700
And I know I dropped off come
from kind of the group notion.

00:08:04.700 --> 00:08:07.280
But let me just actually write
the valence electrons.

00:08:07.280 --> 00:08:09.220
So these all have three
valence electrons.

00:08:09.220 --> 00:08:13.720
Four, five, six, seven.

00:08:13.720 --> 00:08:16.680
So these all have three
electrons in

00:08:16.680 --> 00:08:18.150
its outermost shell.

00:08:18.150 --> 00:08:21.420
It still seems easier for them
to give them away than to take

00:08:21.420 --> 00:08:25.990
them, but maybe now, in certain
cases, there could be,

00:08:25.990 --> 00:08:27.910
especially in the case of, let's
say, boron, there could

00:08:27.910 --> 00:08:31.180
be a situation where it maybe
could gain five electrons,

00:08:31.180 --> 00:08:32.820
although that seems hard.

00:08:32.820 --> 00:08:35.090
It's much easier to give away
three and that's why a lot of

00:08:35.090 --> 00:08:37.470
the, quote-unquote,
official metals

00:08:37.470 --> 00:08:39.340
show up in this category.

00:08:39.340 --> 00:08:43.230
And as you can see, as you go
down the periodic table you

00:08:43.230 --> 00:08:45.480
can kind of have metals
that have more and

00:08:45.480 --> 00:08:46.650
more valence electrons.

00:08:46.650 --> 00:08:50.730
So for, let's say, lead.

00:08:50.730 --> 00:08:52.120
It's still a metal,
even though it has

00:08:52.120 --> 00:08:53.690
four valence electrons.

00:08:53.690 --> 00:09:00.490
And that's because the atom is
so big, its radius is so large

00:09:00.490 --> 00:09:03.030
that the outermost shell is so
far away from the nucleus,

00:09:03.030 --> 00:09:05.150
that those electrons are
easier to take off.

00:09:05.150 --> 00:09:08.510
So for example, as you go down,
carbon, those electrons

00:09:08.510 --> 00:09:10.470
are very close to the nucleus.

00:09:10.470 --> 00:09:11.820
So they're very hard
to take off.

00:09:11.820 --> 00:09:15.290
So carbon would probably more
likely gain electrons from

00:09:15.290 --> 00:09:16.840
somebody else to get to eight.

00:09:16.840 --> 00:09:20.270
While these guys' valence
electrons are so far away from

00:09:20.270 --> 00:09:23.070
the nucleus that they're more
likely to kind of want to get

00:09:23.070 --> 00:09:25.440
rid of them to get to eight and
get back to an electron

00:09:25.440 --> 00:09:27.960
configuration of, let's
say, xenon.

00:09:27.960 --> 00:09:32.260
And you go and then these
guys are the nonmetals.

00:09:32.260 --> 00:09:32.600
Right?

00:09:32.600 --> 00:09:34.560
They're likely to probably gain

00:09:34.560 --> 00:09:36.330
electrons in most reactions.

00:09:36.330 --> 00:09:38.820
And then this yellow category
that I said was highly

00:09:38.820 --> 00:09:43.720
reactive, especially highly
reactive with the alkali

00:09:43.720 --> 00:09:46.030
metals over here, these
are called halogens.

00:09:46.030 --> 00:09:48.620
And you've probably heard
the word before.

00:09:48.620 --> 00:09:49.870
Halogen lamps.

00:09:54.980 --> 00:09:57.930
That's no mistake there to
call them halogen lamps.

00:09:57.930 --> 00:10:00.070
That's not a random
choice of words.

00:10:00.070 --> 00:10:02.560
Maybe I'll do a video on halogen
lamps in the future.

00:10:02.560 --> 00:10:05.260
And then finally, we're
at the noble gases.

00:10:05.260 --> 00:10:07.760
What's interesting about
the noble gases?

00:10:07.760 --> 00:10:10.000
Well they have eight
electrons in their

00:10:10.000 --> 00:10:11.540
outermost shell, right?

00:10:11.540 --> 00:10:12.220
Except for helium.

00:10:12.220 --> 00:10:13.850
Helium has two, right?

00:10:13.850 --> 00:10:19.010
Helium's electron configuration
is 1s2.

00:10:19.010 --> 00:10:21.250
But all of these other guys,
this guy's electron

00:10:21.250 --> 00:10:22.290
configuration is 1s2.

00:10:22.290 --> 00:10:24.040
This is neon.

00:10:24.040 --> 00:10:28.050
1s2, 2s2, 2p6.

00:10:28.050 --> 00:10:30.510
So he has eight electrons
in his outermost shell.

00:10:30.510 --> 00:10:31.370
So he's happy.

00:10:31.370 --> 00:10:32.960
Argon, same thing.

00:10:32.960 --> 00:10:38.010
The outermost shell will
look like 3s2, 3p6.

00:10:38.010 --> 00:10:41.050
Krypton will have in
its outermost shell

00:10:41.050 --> 00:10:43.000
will be 3s2, 3p6.

00:10:43.000 --> 00:10:45.750
It will also have some 3d
electrons around as it

00:10:45.750 --> 00:10:47.840
backfilled back here.

00:10:47.840 --> 00:10:50.070
But all of these have eight
in its outermost shell, so

00:10:50.070 --> 00:10:51.000
they're happy.

00:10:51.000 --> 00:10:52.680
They have no incentive
to react.

00:10:52.680 --> 00:10:54.700
They're kind of like, hey, all
of you other elements, just,

00:10:54.700 --> 00:10:57.720
you know, you guys can do all
that crazy reactions that

00:10:57.720 --> 00:10:58.960
you've got to do,
but we're happy.

00:10:58.960 --> 00:11:00.850
And we don't want to give
or take electrons.

00:11:00.850 --> 00:11:06.130
And because of that these guys
are highly, highly unreactive.

00:11:06.130 --> 00:11:08.460
Very, very unreactive.

00:11:08.460 --> 00:11:11.550
And you know, back in the day,
when they used to make these

00:11:11.550 --> 00:11:17.150
kind of zeppelins, these big
blimps-- the Hindenburg is a

00:11:17.150 --> 00:11:19.290
famous example-- they
used hydrogen.

00:11:19.290 --> 00:11:22.380
And obviously hydrogen is a
pretty reactive substance.

00:11:22.380 --> 00:11:24.560
It's actually very combustible
and that's why it blows up

00:11:24.560 --> 00:11:29.630
very fast. And that's why now,
clowns or children's balloon

00:11:29.630 --> 00:11:33.930
manufacturers, they instead
would prefer to use helium.

00:11:33.930 --> 00:11:36.840
Because helium is a noble gas
and it's very unreactive.

00:11:36.840 --> 00:11:41.150
And it's very unlikely
to explode at a

00:11:41.150 --> 00:11:42.790
child's birthday party.

00:11:42.790 --> 00:11:45.300
But anyway, I think I'm done
now with this video.

00:11:45.300 --> 00:11:47.780
And in the next video we'll talk
a little bit more about

00:11:47.780 --> 00:11:50.820
trends across the
periodic table.