WEBVTT

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In the last video we talked
about how every atom really

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wants to have eight-- let me
write that down-- eight

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electrons in its outermost
shell.

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This is kind of the most stable
configuration that an

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electron can have. And given
this fact that's been

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determined just by observing
the world, really, we can

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start to figure out what's
likely to happen in different

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groups of the periodic table.

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A group of a periodic table
is just a column of

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the periodic table.

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Like this group, right here, and
actually I'll start with

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this group, because it's
got a special name.

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This group right here is
called the noble gases.

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And what's common when you
go down a group in

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the periodic table?

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What's common about a column
in the periodic table?

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Well, in the last video we saw
that every element in a column

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has the same number of
valence electrons.

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Or it has the same number
of electrons in

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its outermost shell.

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And we figured out
what that was.

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This column, right here, which
we learned were the alkali

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metals, this has one electron
in its outermost shell.

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And I made that one caveat
that hydrogen isn't

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necessarily considered
an alkali metal.

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One, it's usually not
in metal form.

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And it doesn't want to give
away electrons as much as

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other metals do.

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When people talk about
metal-like characteristics of

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an element, they're really
talking about how likely it is

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to give away electron.

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We'll talk about other
characteristics of a metal,

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especially the way that we
perceive metals as being

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shiny, and maybe they conduct
electricity, and see how that

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plays out in the
periodic table.

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But anyway, back to what
I was talking about.

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This column, right here,
this is called the

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alkaline earth metals.

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So this is alkaline earth.

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These all have two atoms
in its outermost shell.

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So remember, everyone wants
to get to eight.

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If these guys wanted to get to
eight by adding electrons,

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they would have a
long way to go.

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This way, we would have to
add seven electrons.

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They would have to add
six electrons.

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And who are they going
to take it from?

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Because these guys don't want to
give away their electrons.

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They're so close to
getting to eight.

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So it's much easier when you're
on the left-hand side

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of the periodic table to
give away electrons.

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In fact, when you only have one
to give away-- especially

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in the case of elements other
than hydrogen-- when you only

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have one to give away, it
really wants to do that.

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And because of that, these
elements right here are very

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seldom found in their
elemental state.

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When I say elemental state, it
means there's nothing but

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lithium there, there's nothing
but sodium there, there's

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nothing but potassium there.

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They're very likely, if you
find this, it's probably

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already reacted with
something.

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Probably with something on
this side of the periodic

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table, because this wants to
give away something really

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bad, this wants to take
something really bad.

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So the reaction will
probably happen.

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These are still reactive.

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The alkaline earth metals are
still reactive, but not as

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reactive as the alkali metals.

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And that's because these guys
are really close to getting to

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the stable magic eight number.

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These guys are a little
bit further away.

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So it takes a little bit more,
I guess you could say, of a

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push for them to
give away two.

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These guys only have
to give away one.

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And then we learned that
this has two in

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its outermost shell.

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And then all of these elements,
which are called the

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transition metals, as you add
electrons, they're just

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backfilling the previous
shell's d subshell.

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Right?

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So their outermost shell
still has two.

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It still has those.

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If this is the fourth period,
all of these elements'

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outermost shell has 4s2.

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And these elements are just
backfilling their 3d

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suborbital.

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Or their 3d subshell.

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These are 2's.

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So these all have two
outermost electrons.

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So all of these, like the
alkaline earth metals, need to

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lose two electrons in order to,
quote-unquote, be happy.

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And the way I think about this,
and this is really just

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a way-- and it maybe it bears
out in physical reality-- is

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that these guys have kind of
a deep bench of electrons.

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That if they are able to shed
some of these valence

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electrons-- so if I write iron
has two valence electrons like

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that-- even if they shed these
electrons, they kind of have a

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reserve of electrons in
the d subshell for

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the previous shell.

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So if it sheds its 4s2
electrons, it still has all

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those 3d electrons that have a
high energy state that can

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maybe kind of replace them.

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And I'll use everything in
quotation marks, because these

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are just ways for me to
visualize things.

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And the reason why I make that
point is because metals are

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just very giving with
their electrons.

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And these guys react.

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They say, hey, take
my electrons.

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These guys say, take these
two electrons.

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And these guys, they start to
say, especially as you fill

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the d subshell, I've got these
two electrons, and not only do

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I have those two electrons,
but I have more electrons

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where-- well almost where--
that came from.

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I have some in reserve
in my d.

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And what happens in these
transition metals, and it

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especially happens in the
metals-- so these are the

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metals right here, and these
don't follow just a group, but

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this is the metals, this color
right here-- is that they have

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so many electrons to hand off,
not only do they have these

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extra there, but they filled
their d subshell, that they

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can kind of, especially when
they're in elemental form, and

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when I say elemental form, this
means that you just have

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a big block of aluminum.

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Aluminum hasn't reacted with
anything like oxygen.

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It's just a bunch of aluminum.

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Right?

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When you have a bunch of
aluminum, what happens is you

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have these metallic bonds where
all of the aluminum

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atoms say, you know what, I have
all these extra, I have

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definitely, in the case of
aluminum, three electrons in

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my outermost shell.

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But I have all of these kind of
backfilled electrons in my

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d suborbital.

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I'm just going to share them
with the other aluminum atoms.

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So you create this sea of
aluminum atoms. And they're

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attracted to each other.

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Or you create this sea of
aluminum electrons.

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So you have a bunch of electrons
sitting in between

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the atoms, and since the atoms
kind of donated these

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electrons, they're attracted
to them.

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Right?

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So the actual atoms-- so this
would be an aluminum plus, and

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maybe we would have donated
three electrons.

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But I'm not being exact here.

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I want to just give you the
sense of how things work.

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And that's why metals conduct
really well, because

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electricity is just a bunch of
electrons moving, and in order

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to have electrons moving, you
have to have surplus electrons

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lying around.

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So elements right around this
area are really good

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conductors.

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In fact, silver is the
best conductor.

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Silver, right here, is the best
conductor on the planet.

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And the reason why that's not
used for our wiring and copper

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is because copper is easier
to find than silver.

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But silver is the
best conductor.

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And the way I think about it
is that these-- once you've

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filled an orbital, that orbital

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becomes somewhat stable.

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So all of these guys have
filled their d orbital.

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While these guys, their d
orbital is not filled.

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So they just have a lot of
surplus electrons that are

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really good for conduction.

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Now, that's just an intuition.

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I haven't done the experiment
to prove that.

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But it'll give you a
sense of why things

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conduct and all of that.

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So these are the transition
metals.

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These are actually considered
the metals.

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But the reason why these are
considered the transition

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metals is because they're
filling the d-block.

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But transition metals kind
of sound like not

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as good as a metal.

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But when I think of metals,
iron is kind of the first

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metal I always think of.

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I definitely think of silver and
copper and gold as metals.

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So to call them transition
metals is a little not fair.

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I don't really consider aluminum
more of a metal than,

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let's say, iron is.

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But in chemistry classification
world, aluminum

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is more of a metal.

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These elements right here.

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And I know I dropped off come
from kind of the group notion.

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But let me just actually write
the valence electrons.

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So these all have three
valence electrons.

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Four, five, six, seven.

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So these all have three
electrons in

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its outermost shell.

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It still seems easier for them
to give them away than to take

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them, but maybe now, in certain
cases, there could be,

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especially in the case of, let's
say, boron, there could

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be a situation where it maybe
could gain five electrons,

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although that seems hard.

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It's much easier to give away
three and that's why a lot of

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the, quote-unquote,
official metals

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show up in this category.

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And as you can see, as you go
down the periodic table you

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can kind of have metals
that have more and

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more valence electrons.

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So for, let's say, lead.

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It's still a metal,
even though it has

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four valence electrons.

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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.

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So for example, as you go down,
carbon, those electrons

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are very close to the nucleus.

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So they're very hard
to take off.

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So carbon would probably more
likely gain electrons from

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somebody else to get to eight.

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While these guys' valence
electrons are so far away from

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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

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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?

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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.

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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.