Groups of the Periodic Table

Properties of alkali, alkaline earth and transition metals. Halogens and noble gases.

In the last video we talked
about how every atom really

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

electrons in its outermost
shell.

This is kind of the most stable
configuration that an

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

determined just by observing
the world, really, we can

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

groups of the periodic table.

A group of a periodic table
is just a column of

the periodic table.

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

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

This group right here is
called the noble gases.

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

the periodic table?

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

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

has the same number of
valence electrons.

Or it has the same number
of electrons in

its outermost shell.

And we figured out
what that was.

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

metals, this has one electron
in its outermost shell.

And I made that one caveat
that hydrogen isn't

necessarily considered
an alkali metal.

One, it's usually not
in metal form.

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

other metals do.

When people talk about
metal-like characteristics of

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

to give away electron.

We'll talk about other
characteristics of a metal,

especially the way that we
perceive metals as being

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

plays out in the
periodic table.

But anyway, back to what
I was talking about.

This column, right here,
this is called the

alkaline earth metals.

So this is alkaline earth.

These all have two atoms
in its outermost shell.

So remember, everyone wants
to get to eight.

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

they would have a
long way to go.

This way, we would have to
add seven electrons.

They would have to add
six electrons.

And who are they going
to take it from?

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

They're so close to
getting to eight.

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

of the periodic table to
give away electrons.

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

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

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

And because of that, these
elements right here are very

seldom found in their
elemental state.

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

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

nothing but potassium there.

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

already reacted with
something.

Probably with something on
this side of the periodic

table, because this wants to
give away something really

bad, this wants to take
something really bad.

So the reaction will
probably happen.

These are still reactive.

The alkaline earth metals are
still reactive, but not as

reactive as the alkali metals.

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

the stable magic eight number.

These guys are a little
bit further away.

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

push for them to
give away two.

These guys only have
to give away one.

And then we learned that
this has two in

its outermost shell.

And then all of these elements,
which are called the

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

backfilling the previous
shell's d subshell.

Right?

So their outermost shell
still has two.

It still has those.

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

outermost shell has 4s2.

And these elements are just
backfilling their 3d

suborbital.

Or their 3d subshell.

These are 2's.

So these all have two
outermost electrons.

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

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

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

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

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

That if they are able to shed
some of these valence

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

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

reserve of electrons in
the d subshell for

the previous shell.

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

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

maybe kind of replace them.

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

are just ways for me to
visualize things.

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

just very giving with
their electrons.

And these guys react.

They say, hey, take
my electrons.

These guys say, take these
two electrons.

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

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

I have those two electrons,
but I have more electrons

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

I have some in reserve
in my d.

And what happens in these
transition metals, and it

especially happens in the
metals-- so these are the

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

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

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

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

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

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

a big block of aluminum.

Aluminum hasn't reacted with
anything like oxygen.

It's just a bunch of aluminum.

Right?

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

have these metallic bonds where
all of the aluminum

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

definitely, in the case of
aluminum, three electrons in

my outermost shell.

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

d suborbital.

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

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

attracted to each other.

Or you create this sea of
aluminum electrons.

So you have a bunch of electrons
sitting in between

the atoms, and since the atoms
kind of donated these

electrons, they're attracted
to them.

Right?

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

maybe we would have donated
three electrons.

But I'm not being exact here.

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

And that's why metals conduct
really well, because

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

to have electrons moving, you
have to have surplus electrons

lying around.

So elements right around this
area are really good

conductors.

In fact, silver is the
best conductor.

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

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

is because copper is easier
to find than silver.

But silver is the
best conductor.

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

filled an orbital, that orbital

becomes somewhat stable.

So all of these guys have
filled their d orbital.

While these guys, their d
orbital is not filled.

So they just have a lot of
surplus electrons that are

really good for conduction.

Now, that's just an intuition.

I haven't done the experiment
to prove that.

But it'll give you a
sense of why things

conduct and all of that.

So these are the transition
metals.

These are actually considered
the metals.

But the reason why these are
considered the transition

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

But transition metals kind
of sound like not

as good as a metal.

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

metal I always think of.

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

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

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

let's say, iron is.

But in chemistry classification
world, aluminum

is more of a metal.

These elements right here.

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

But let me just actually write
the valence electrons.

So these all have three
valence electrons.

Four, five, six, seven.

So these all have three
electrons in

its outermost shell.

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

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

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

be a situation where it maybe
could gain five electrons,

although that seems hard.

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

the, quote-unquote,
official metals

show up in this category.

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

can kind of have metals
that have more and

more valence electrons.

So for, let's say, lead.

It's still a metal,
even though it has

four valence electrons.

And that's because the atom is
so big, its radius is so large

that the outermost shell is so
far away from the nucleus,

that those electrons are
easier to take off.

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

are very close to the nucleus.

So they're very hard
to take off.

So carbon would probably more
likely gain electrons from

somebody else to get to eight.

While these guys' valence
electrons are so far away from

the nucleus that they're more
likely to kind of want to get

rid of them to get to eight and
get back to an electron

configuration of, let's
say, xenon.

And you go and then these
guys are the nonmetals.

Right?

They're likely to probably gain

electrons in most reactions.

And then this yellow category
that I said was highly

reactive, especially highly
reactive with the alkali

metals over here, these
are called halogens.

And you've probably heard
the word before.

Halogen lamps.

That's no mistake there to
call them halogen lamps.

That's not a random
choice of words.

Maybe I'll do a video on halogen
lamps in the future.

And then finally, we're
at the noble gases.

What's interesting about
the noble gases?

Well they have eight
electrons in their

outermost shell, right?

Except for helium.

Helium has two, right?

Helium's electron configuration
is 1s2.

But all of these other guys,
this guy's electron

configuration is 1s2.

This is neon.

1s2, 2s2, 2p6.

So he has eight electrons
in his outermost shell.

So he's happy.

Argon, same thing.

The outermost shell will
look like 3s2, 3p6.

Krypton will have in
its outermost shell

will be 3s2, 3p6.

It will also have some 3d
electrons around as it

backfilled back here.

But all of these have eight
in its outermost shell, so

they're happy.

They have no incentive
to react.

They're kind of like, hey, all
of you other elements, just,

you know, you guys can do all
that crazy reactions that

you've got to do,
but we're happy.

And we don't want to give
or take electrons.

And because of that these guys
are highly, highly unreactive.

Very, very unreactive.

And you know, back in the day,
when they used to make these

kind of zeppelins, these big
blimps-- the Hindenburg is a

famous example-- they
used hydrogen.

And obviously hydrogen is a
pretty reactive substance.

It's actually very combustible
and that's why it blows up

very fast. And that's why now,
clowns or children's balloon

manufacturers, they instead
would prefer to use helium.

Because helium is a noble gas
and it's very unreactive.

And it's very unlikely
to explode at a

child's birthday party.

But anyway, I think I'm done
now with this video.

And in the next video we'll talk
a little bit more about

trends across the
periodic table.