0:00:00.840,0:00:04.740
In the last video we talked[br]about how every atom really

0:00:04.740,0:00:08.280
wants to have eight-- let me[br]write that down-- eight

0:00:08.280,0:00:11.030
electrons in its outermost[br]shell.

0:00:11.030,0:00:14.510
This is kind of the most stable[br]configuration that an

0:00:14.510,0:00:17.740
electron can have. And given[br]this fact that's been

0:00:17.740,0:00:21.180
determined just by observing[br]the world, really, we can

0:00:21.180,0:00:24.420
start to figure out what's[br]likely to happen in different

0:00:24.420,0:00:26.350
groups of the periodic table.

0:00:26.350,0:00:28.820
A group of a periodic table[br]is just a column of

0:00:28.820,0:00:30.220
the periodic table.

0:00:30.220,0:00:32.479
Like this group, right here, and[br]actually I'll start with

0:00:32.479,0:00:35.960
this group, because it's[br]got a special name.

0:00:35.960,0:00:39.160
This group right here is[br]called the noble gases.

0:00:39.160,0:00:41.860
And what's common when you[br]go down a group in

0:00:41.860,0:00:42.900
the periodic table?

0:00:42.900,0:00:45.970
What's common about a column[br]in the periodic table?

0:00:45.970,0:00:50.100
Well, in the last video we saw[br]that every element in a column

0:00:50.100,0:00:52.700
has the same number of[br]valence electrons.

0:00:52.700,0:00:55.220
Or it has the same number[br]of electrons in

0:00:55.220,0:00:56.580
its outermost shell.

0:00:56.580,0:00:58.000
And we figured out[br]what that was.

0:00:58.000,0:01:01.160
This column, right here, which[br]we learned were the alkali

0:01:01.160,0:01:05.830
metals, this has one electron[br]in its outermost shell.

0:01:05.830,0:01:08.530
And I made that one caveat[br]that hydrogen isn't

0:01:08.530,0:01:10.830
necessarily considered[br]an alkali metal.

0:01:10.830,0:01:13.230
One, it's usually not[br]in metal form.

0:01:13.230,0:01:16.320
And it doesn't want to give[br]away electrons as much as

0:01:16.320,0:01:17.490
other metals do.

0:01:17.490,0:01:21.080
When people talk about[br]metal-like characteristics of

0:01:21.080,0:01:23.160
an element, they're really[br]talking about how likely it is

0:01:23.160,0:01:24.640
to give away electron.

0:01:24.640,0:01:26.460
We'll talk about other[br]characteristics of a metal,

0:01:26.460,0:01:30.020
especially the way that we[br]perceive metals as being

0:01:30.020,0:01:32.610
shiny, and maybe they conduct[br]electricity, and see how that

0:01:32.610,0:01:34.060
plays out in the[br]periodic table.

0:01:34.060,0:01:35.760
But anyway, back to what[br]I was talking about.

0:01:35.760,0:01:37.610
This column, right here,[br]this is called the

0:01:37.610,0:01:40.680
alkaline earth metals.

0:01:40.680,0:01:42.420
So this is alkaline earth.

0:01:51.130,0:01:54.340
These all have two atoms[br]in its outermost shell.

0:01:54.340,0:01:56.450
So remember, everyone wants[br]to get to eight.

0:01:56.450,0:02:00.070
If these guys wanted to get to[br]eight by adding electrons,

0:02:00.070,0:02:01.130
they would have a[br]long way to go.

0:02:01.130,0:02:03.570
This way, we would have to[br]add seven electrons.

0:02:03.570,0:02:05.850
They would have to add[br]six electrons.

0:02:05.850,0:02:07.340
And who are they going[br]to take it from?

0:02:07.340,0:02:09.090
Because these guys don't want to[br]give away their electrons.

0:02:09.090,0:02:10.860
They're so close to[br]getting to eight.

0:02:10.860,0:02:12.980
So it's much easier when you're[br]on the left-hand side

0:02:12.980,0:02:15.350
of the periodic table to[br]give away electrons.

0:02:15.350,0:02:19.120
In fact, when you only have one[br]to give away-- especially

0:02:19.120,0:02:22.150
in the case of elements other[br]than hydrogen-- when you only

0:02:22.150,0:02:24.980
have one to give away, it[br]really wants to do that.

0:02:24.980,0:02:28.330
And because of that, these[br]elements right here are very

0:02:28.330,0:02:30.440
seldom found in their[br]elemental state.

0:02:30.440,0:02:32.900
When I say elemental state, it[br]means there's nothing but

0:02:32.900,0:02:36.730
lithium there, there's nothing[br]but sodium there, there's

0:02:36.730,0:02:37.950
nothing but potassium there.

0:02:37.950,0:02:40.610
They're very likely, if you[br]find this, it's probably

0:02:40.610,0:02:42.530
already reacted with[br]something.

0:02:42.530,0:02:44.470
Probably with something on[br]this side of the periodic

0:02:44.470,0:02:46.520
table, because this wants to[br]give away something really

0:02:46.520,0:02:49.150
bad, this wants to take[br]something really bad.

0:02:49.150,0:02:51.340
So the reaction will[br]probably happen.

0:02:51.340,0:02:53.100
These are still reactive.

0:02:53.100,0:02:56.200
The alkaline earth metals are[br]still reactive, but not as

0:02:56.200,0:02:59.160
reactive as the alkali metals.

0:02:59.160,0:03:02.090
And that's because these guys[br]are really close to getting to

0:03:02.090,0:03:03.840
the stable magic eight number.

0:03:03.840,0:03:06.210
These guys are a little[br]bit further away.

0:03:06.210,0:03:12.420
So it takes a little bit more,[br]I guess you could say, of a

0:03:12.420,0:03:14.670
push for them to[br]give away two.

0:03:14.670,0:03:16.820
These guys only have[br]to give away one.

0:03:16.820,0:03:19.485
And then we learned that[br]this has two in

0:03:19.485,0:03:20.440
its outermost shell.

0:03:20.440,0:03:23.140
And then all of these elements,[br]which are called the

0:03:23.140,0:03:26.710
transition metals, as you add[br]electrons, they're just

0:03:26.710,0:03:31.410
backfilling the previous[br]shell's d subshell.

0:03:31.410,0:03:31.940
Right?

0:03:31.940,0:03:34.920
So their outermost shell[br]still has two.

0:03:34.920,0:03:36.660
It still has those.

0:03:36.660,0:03:41.300
If this is the fourth period,[br]all of these elements'

0:03:41.300,0:03:45.460
outermost shell has 4s2.

0:03:45.460,0:03:48.560
And these elements are just[br]backfilling their 3d

0:03:48.560,0:03:50.720
suborbital.

0:03:50.720,0:03:52.950
Or their 3d subshell.

0:03:52.950,0:03:54.690
These are 2's.

0:03:54.690,0:03:57.400
So these all have two[br]outermost electrons.

0:03:57.400,0:04:01.190
So all of these, like the[br]alkaline earth metals, need to

0:04:01.190,0:04:06.320
lose two electrons in order to,[br]quote-unquote, be happy.

0:04:06.320,0:04:08.410
And the way I think about this,[br]and this is really just

0:04:08.410,0:04:11.810
a way-- and it maybe it bears[br]out in physical reality-- is

0:04:11.810,0:04:14.870
that these guys have kind of[br]a deep bench of electrons.

0:04:14.870,0:04:19.649
That if they are able to shed[br]some of these valence

0:04:19.649,0:04:25.580
electrons-- so if I write iron[br]has two valence electrons like

0:04:25.580,0:04:29.890
that-- even if they shed these[br]electrons, they kind of have a

0:04:29.890,0:04:34.660
reserve of electrons in[br]the d subshell for

0:04:34.660,0:04:36.420
the previous shell.

0:04:36.420,0:04:40.980
So if it sheds its 4s2[br]electrons, it still has all

0:04:40.980,0:04:43.740
those 3d electrons that have a[br]high energy state that can

0:04:43.740,0:04:45.650
maybe kind of replace them.

0:04:45.650,0:04:47.930
And I'll use everything in[br]quotation marks, because these

0:04:47.930,0:04:50.770
are just ways for me to[br]visualize things.

0:04:50.770,0:04:55.010
And the reason why I make that[br]point is because metals are

0:04:55.010,0:04:58.020
just very giving with[br]their electrons.

0:04:58.020,0:05:00.380
And these guys react.

0:05:00.380,0:05:01.780
They say, hey, take[br]my electrons.

0:05:01.780,0:05:03.680
These guys say, take these[br]two electrons.

0:05:03.680,0:05:06.680
And these guys, they start to[br]say, especially as you fill

0:05:06.680,0:05:09.260
the d subshell, I've got these[br]two electrons, and not only do

0:05:09.260,0:05:11.420
I have those two electrons,[br]but I have more electrons

0:05:11.420,0:05:13.520
where-- well almost where--[br]that came from.

0:05:13.520,0:05:16.050
I have some in reserve[br]in my d.

0:05:16.050,0:05:18.690
And what happens in these[br]transition metals, and it

0:05:18.690,0:05:21.470
especially happens in the[br]metals-- so these are the

0:05:21.470,0:05:24.110
metals right here, and these[br]don't follow just a group, but

0:05:24.110,0:05:27.960
this is the metals, this color[br]right here-- is that they have

0:05:27.960,0:05:31.940
so many electrons to hand off,[br]not only do they have these

0:05:31.940,0:05:35.370
extra there, but they filled[br]their d subshell, that they

0:05:35.370,0:05:37.660
can kind of, especially when[br]they're in elemental form, and

0:05:37.660,0:05:39.820
when I say elemental form, this[br]means that you just have

0:05:39.820,0:05:41.450
a big block of aluminum.

0:05:41.450,0:05:45.700
Aluminum hasn't reacted with[br]anything like oxygen.

0:05:45.700,0:05:47.500
It's just a bunch of aluminum.

0:05:47.500,0:05:47.810
Right?

0:05:47.810,0:05:49.640
When you have a bunch of[br]aluminum, what happens is you

0:05:49.640,0:05:51.840
have these metallic bonds where[br]all of the aluminum

0:05:51.840,0:05:54.550
atoms say, you know what, I have[br]all these extra, I have

0:05:54.550,0:05:58.525
definitely, in the case of[br]aluminum, three electrons in

0:05:58.525,0:05:59.470
my outermost shell.

0:05:59.470,0:06:02.840
But I have all of these kind of[br]backfilled electrons in my

0:06:02.840,0:06:04.040
d suborbital.

0:06:04.040,0:06:06.600
I'm just going to share them[br]with the other aluminum atoms.

0:06:06.600,0:06:09.170
So you create this sea of[br]aluminum atoms. And they're

0:06:09.170,0:06:10.430
attracted to each other.

0:06:10.430,0:06:12.750
Or you create this sea of[br]aluminum electrons.

0:06:12.750,0:06:20.090
So you have a bunch of electrons[br]sitting in between

0:06:20.090,0:06:22.620
the atoms, and since the atoms[br]kind of donated these

0:06:22.620,0:06:24.270
electrons, they're attracted[br]to them.

0:06:24.270,0:06:24.950
Right?

0:06:24.950,0:06:30.030
So the actual atoms-- so this[br]would be an aluminum plus, and

0:06:30.030,0:06:31.405
maybe we would have donated[br]three electrons.

0:06:31.405,0:06:33.470
But I'm not being exact here.

0:06:33.470,0:06:35.410
I want to just give you the[br]sense of how things work.

0:06:35.410,0:06:38.320
And that's why metals conduct[br]really well, because

0:06:38.320,0:06:41.320
electricity is just a bunch of[br]electrons moving, and in order

0:06:41.320,0:06:45.460
to have electrons moving, you[br]have to have surplus electrons

0:06:45.460,0:06:46.330
lying around.

0:06:46.330,0:06:48.480
So elements right around this[br]area are really good

0:06:48.480,0:06:48.980
conductors.

0:06:48.980,0:06:53.650
In fact, silver is the[br]best conductor.

0:06:53.650,0:06:57.240
Silver, right here, is the best[br]conductor on the planet.

0:06:57.240,0:07:01.440
And the reason why that's not[br]used for our wiring and copper

0:07:01.440,0:07:04.300
is because copper is easier[br]to find than silver.

0:07:04.300,0:07:06.140
But silver is the[br]best conductor.

0:07:06.140,0:07:09.340
And the way I think about it[br]is that these-- once you've

0:07:09.340,0:07:11.010
filled an orbital, that orbital

0:07:11.010,0:07:12.890
becomes somewhat stable.

0:07:12.890,0:07:16.140
So all of these guys have[br]filled their d orbital.

0:07:16.140,0:07:18.960
While these guys, their d[br]orbital is not filled.

0:07:18.960,0:07:20.910
So they just have a lot of[br]surplus electrons that are

0:07:20.910,0:07:21.970
really good for conduction.

0:07:21.970,0:07:24.120
Now, that's just an intuition.

0:07:24.120,0:07:26.000
I haven't done the experiment[br]to prove that.

0:07:26.000,0:07:28.100
But it'll give you a[br]sense of why things

0:07:28.100,0:07:29.100
conduct and all of that.

0:07:29.100,0:07:32.370
So these are the transition[br]metals.

0:07:32.370,0:07:33.870
These are actually considered[br]the metals.

0:07:33.870,0:07:35.940
But the reason why these are[br]considered the transition

0:07:35.940,0:07:37.960
metals is because they're[br]filling the d-block.

0:07:37.960,0:07:40.600
But transition metals kind[br]of sound like not

0:07:40.600,0:07:41.390
as good as a metal.

0:07:41.390,0:07:44.460
But when I think of metals,[br]iron is kind of the first

0:07:44.460,0:07:45.610
metal I always think of.

0:07:45.610,0:07:49.020
I definitely think of silver and[br]copper and gold as metals.

0:07:49.020,0:07:51.270
So to call them transition[br]metals is a little not fair.

0:07:51.270,0:07:54.120
I don't really consider aluminum[br]more of a metal than,

0:07:54.120,0:07:55.230
let's say, iron is.

0:07:55.230,0:07:58.140
But in chemistry classification[br]world, aluminum

0:07:58.140,0:08:00.370
is more of a metal.

0:08:00.370,0:08:01.880
These elements right here.

0:08:01.880,0:08:04.700
And I know I dropped off come[br]from kind of the group notion.

0:08:04.700,0:08:07.280
But let me just actually write[br]the valence electrons.

0:08:07.280,0:08:09.220
So these all have three[br]valence electrons.

0:08:09.220,0:08:13.720
Four, five, six, seven.

0:08:13.720,0:08:16.680
So these all have three[br]electrons in

0:08:16.680,0:08:18.150
its outermost shell.

0:08:18.150,0:08:21.420
It still seems easier for them[br]to give them away than to take

0:08:21.420,0:08:25.990
them, but maybe now, in certain[br]cases, there could be,

0:08:25.990,0:08:27.910
especially in the case of, let's[br]say, boron, there could

0:08:27.910,0:08:31.180
be a situation where it maybe[br]could gain five electrons,

0:08:31.180,0:08:32.820
although that seems hard.

0:08:32.820,0:08:35.090
It's much easier to give away[br]three and that's why a lot of

0:08:35.090,0:08:37.470
the, quote-unquote,[br]official metals

0:08:37.470,0:08:39.340
show up in this category.

0:08:39.340,0:08:43.230
And as you can see, as you go[br]down the periodic table you

0:08:43.230,0:08:45.480
can kind of have metals[br]that have more and

0:08:45.480,0:08:46.650
more valence electrons.

0:08:46.650,0:08:50.730
So for, let's say, lead.

0:08:50.730,0:08:52.120
It's still a metal,[br]even though it has

0:08:52.120,0:08:53.690
four valence electrons.

0:08:53.690,0:09:00.490
And that's because the atom is[br]so big, its radius is so large

0:09:00.490,0:09:03.030
that the outermost shell is so[br]far away from the nucleus,

0:09:03.030,0:09:05.150
that those electrons are[br]easier to take off.

0:09:05.150,0:09:08.510
So for example, as you go down,[br]carbon, those electrons

0:09:08.510,0:09:10.470
are very close to the nucleus.

0:09:10.470,0:09:11.820
So they're very hard[br]to take off.

0:09:11.820,0:09:15.290
So carbon would probably more[br]likely gain electrons from

0:09:15.290,0:09:16.840
somebody else to get to eight.

0:09:16.840,0:09:20.270
While these guys' valence[br]electrons are so far away from

0:09:20.270,0:09:23.070
the nucleus that they're more[br]likely to kind of want to get

0:09:23.070,0:09:25.440
rid of them to get to eight and[br]get back to an electron

0:09:25.440,0:09:27.960
configuration of, let's[br]say, xenon.

0:09:27.960,0:09:32.260
And you go and then these[br]guys are the nonmetals.

0:09:32.260,0:09:32.600
Right?

0:09:32.600,0:09:34.560
They're likely to probably gain

0:09:34.560,0:09:36.330
electrons in most reactions.

0:09:36.330,0:09:38.820
And then this yellow category[br]that I said was highly

0:09:38.820,0:09:43.720
reactive, especially highly[br]reactive with the alkali

0:09:43.720,0:09:46.030
metals over here, these[br]are called halogens.

0:09:46.030,0:09:48.620
And you've probably heard[br]the word before.

0:09:48.620,0:09:49.870
Halogen lamps.

0:09:54.980,0:09:57.930
That's no mistake there to[br]call them halogen lamps.

0:09:57.930,0:10:00.070
That's not a random[br]choice of words.

0:10:00.070,0:10:02.560
Maybe I'll do a video on halogen[br]lamps in the future.

0:10:02.560,0:10:05.260
And then finally, we're[br]at the noble gases.

0:10:05.260,0:10:07.760
What's interesting about[br]the noble gases?

0:10:07.760,0:10:10.000
Well they have eight[br]electrons in their

0:10:10.000,0:10:11.540
outermost shell, right?

0:10:11.540,0:10:12.220
Except for helium.

0:10:12.220,0:10:13.850
Helium has two, right?

0:10:13.850,0:10:19.010
Helium's electron configuration[br]is 1s2.

0:10:19.010,0:10:21.250
But all of these other guys,[br]this guy's electron

0:10:21.250,0:10:22.290
configuration is 1s2.

0:10:22.290,0:10:24.040
This is neon.

0:10:24.040,0:10:28.050
1s2, 2s2, 2p6.

0:10:28.050,0:10:30.510
So he has eight electrons[br]in his outermost shell.

0:10:30.510,0:10:31.370
So he's happy.

0:10:31.370,0:10:32.960
Argon, same thing.

0:10:32.960,0:10:38.010
The outermost shell will[br]look like 3s2, 3p6.

0:10:38.010,0:10:41.050
Krypton will have in[br]its outermost shell

0:10:41.050,0:10:43.000
will be 3s2, 3p6.

0:10:43.000,0:10:45.750
It will also have some 3d[br]electrons around as it

0:10:45.750,0:10:47.840
backfilled back here.

0:10:47.840,0:10:50.070
But all of these have eight[br]in its outermost shell, so

0:10:50.070,0:10:51.000
they're happy.

0:10:51.000,0:10:52.680
They have no incentive[br]to react.

0:10:52.680,0:10:54.700
They're kind of like, hey, all[br]of you other elements, just,

0:10:54.700,0:10:57.720
you know, you guys can do all[br]that crazy reactions that

0:10:57.720,0:10:58.960
you've got to do,[br]but we're happy.

0:10:58.960,0:11:00.850
And we don't want to give[br]or take electrons.

0:11:00.850,0:11:06.130
And because of that these guys[br]are highly, highly unreactive.

0:11:06.130,0:11:08.460
Very, very unreactive.

0:11:08.460,0:11:11.550
And you know, back in the day,[br]when they used to make these

0:11:11.550,0:11:17.150
kind of zeppelins, these big[br]blimps-- the Hindenburg is a

0:11:17.150,0:11:19.290
famous example-- they[br]used hydrogen.

0:11:19.290,0:11:22.380
And obviously hydrogen is a[br]pretty reactive substance.

0:11:22.380,0:11:24.560
It's actually very combustible[br]and that's why it blows up

0:11:24.560,0:11:29.630
very fast. And that's why now,[br]clowns or children's balloon

0:11:29.630,0:11:33.930
manufacturers, they instead[br]would prefer to use helium.

0:11:33.930,0:11:36.840
Because helium is a noble gas[br]and it's very unreactive.

0:11:36.840,0:11:41.150
And it's very unlikely[br]to explode at a

0:11:41.150,0:11:42.790
child's birthday party.

0:11:42.790,0:11:45.300
But anyway, I think I'm done[br]now with this video.

0:11:45.300,0:11:47.780
And in the next video we'll talk[br]a little bit more about

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trends across the[br]periodic table.