Let's talk about ionic bonding in much more depth.
In the previous video we talked about the basic fundamentals of how ionic bonds get
made in sodium chloride.
Now I want to look at why and how these steps happen during the formation of ionic bonds.
In order to really understand what's going on in ionic bonding, we have to take a look
at the individual electrons that live in sodium and live in chlorine.
Now as you probably know, there are specific places in an atom where electrons can live.
Ok I have a diagram of this here.
If this is new, you should check out my video called Valiance Electrons and the Periodic
Table.
Anyway, each one of these little circles represents a spot that an electron can live in in an
atom.
And you'll see that these little electron spots are arranged in rings around the nucleus,
the atom.
Each one of these rings is called a shell or an energy level.
Ok so we can use this diagram to figure out where the electrons live in sodium and where
they live in chlorine.
Ok first thing we've got to do is we've got to find out how many electrons there are in
these two atoms.
Ok now sodium here, you look it up on the periodic table, it's got this 11 here.
That means it has an atomic number of 11, there are 11 protons in sodium.
Now remember when ionic bonding starts, these atoms are not yet ions.
They don't have a charge.
They're neutral.
So that means that they have the same number of protons and electrons.
So there are 11 protons in a sodium atom.
That means there are also 11 electrons in a sodium atom.
Ok the same thing is true of chlorine.
It has an atomic number of 17, 17 protons.
It's starting out without a charge so it has 17 protons and 17 electrons.
Now we can take one of these diagrams and fill it in from the center on out with a number
of electrons.
So for sodium that's going to look like this, 11 electrons arranged around the atom from
the center out.
And for chlorine it's going to look like this, 17 electrons arranged around this from the
center out.
Now you may not be able to tell from these diagrams but these are two very unhappy atoms.
The reason why has to do with their valiance shells.
Do you remember what valiance shells are?
They are the furthest out energy level that still has electrons in them.
Ok so for example this is the valiance shell of sodium.
It's got one electron here.
And this is the valiance shell, the furthest out shell, for chlorine, ok.
The reason why these two atoms are so pissed off is because every atom wants to have a
full valiance shell.
It's like every atoms goal in life.
Sodiums really unhappy because it only has one electron in its valiance shell and it
has these seven empty spots.
Ok chlorine, on the other hand, is also upset because it's got emotionally full valiance
shell but it's got one empty spot.
It's so close, it's so close but it's still super unhappy because the valiance shell isn't
full.
So sodium and chlorine are both unhappy.
They both want to fix their situation and in trying to fix it, that is how they're going
to end up with an ionic bond.
Ok so how are sodium and chlorine going to get happier.
How are they going to fix their situation?
How are they going to try to fill their valiance shells?
Well take a look at this, they can help each other out, ok.
Chlorine has one spot left before it's able to fill its valiance shell.
And so what happens is sodium can give chlorine one of its electrons, ok.
So this electron moves from sodium to chlorine to fill this spot.
Here's what we end up with.
Ok let me just show you what's going on here.
Ok so we got sodium, we got chlorine and this electron up here moves between them.
It leaves sodium and it goes into chlorine.
Ok and now chlorine has filled this empty spot with one of sodiums electrons.
Ok so now chlorine is super happy.
It has a full valiance shell.
It's achieved its goal in life.
But take a look at sodium over here.
Though you may not know it, sodium has also achieved its goal in life because when it
gave this one electron, when it gave the electron to chlorine, it totally emptied out this valiance
shell.
Now you might think, ok that made it even worse because now it has eight empty spots
it has to fill.
But here's the thing, if you can get rid of all of the electrons in your valiance shell,
it's like that valiance shell just disappears.
Sodium doesn't even have to worry about it anymore.
Ok so it gave away its last electron in its valiance shell and now it's like the valiance
shell just disappears and this is now sodiums new valiance shell.
And check it out, it's totally full.
So by giving away that one electron, it could get rid of its whole outer shell and this
is its new valiance shell.
It's full and sodiums happy.
So this is what we end up with.
Let me just show you what the intermediate steps look like here.
And this is what it looks like when sodium gave it away and you can sort of think about
it still having this outer shell and here is chlorine with the new electron from sodium.
So we've got step one, step two, step three.
Ok so now chlorine has a full valiance shell, now sodium got rid of its old valiance shell
and its new valiance shell is totally full.
They're happy.
But let's talk about what's going on with the electrons here, ok, because there're electrons
moving.
Now over here with chlorine, it used to have 17 electrons and then it got a new electron
from sodium.
So it doesn't have 17 electrons anymore.
Now it has an extra one so it has 18 electrons.
But it has the same number of protons because we weren't moving protons in this example,
ok, so it's still got 17 protons and it's got 18 electrons.
But now there's an imbalance between the number of protons and electrons.
It doesn't have the same number of protons and electrons anymore.
It has more electrons which means that it has a negative charge.
It has a negative charge of one minus because it has one more electron that it got from
sodium.
And now we can call it an ion.
Now sodium also became an ion.
Right, it used to have 11 protons and 11 electrons, the same amount so it used to be neutral.
But not anymore because it gave away one of those electrons so now it only has 10.
But it's still got the same number of protons.
It's got 11 protons with positive charge and it's got more protons than electrons.
One more proton.
And that means it's going to have a positive charge, ok.
It's going to have a one plus net charge and it also is going to be an ion, an atom with
a charge.
So this guy over here has a one minus charge, this guy over here has a one plus charge.
Now as we've said before they have opposite charges so we can maybe kind of zoom out a
little bit and take a look what these atoms are going to look like.
We've got a chloride with a negative charge.
We've got sodium with a positive charge.
And they're going to stick together, just like we've shown here.
And that is because opposite charges, oh, opposite charges attract.
We have the positively charged sodium attaching with a negatively charged chlorine and that's
going to give us sodium chloride.
Now the formation of ionic bonds is one of the trickiest concepts in all of chemistry.
So many people are confused by it.
So I just want to go through this one more time really quick, step by step.
Ok so we start out with sodium and chlorine.
They are both neutral.
They have the same number of protons and electrons but they're both unhappy because their valiance
shells are not full.
Chlorine has an empty spot and sodium has only one electron valiance shell.
So the electron here moves from sodium to chlorine.
Ok so now chlorine has one more.
It has a full valiance shell and it's happy.
Sodium empties out its valiance shell so it's almost like that old valiance shell just disappears.
We end up with this and a new valiance shell is totally full.
So now sodium and chlorine are both able to get full valiance shells.
But electrons had to move in this process.
So now sodium has one fewer electron than proton so it gets a one plus charge, chlorine
got one more electron so it has one more electron than proton so it has a one minus charge.
So these guys, they trade electrons, or an electron moves from sodium to chlorine, in
order for them to get full valiance shells.
And it's in the process of that happening that they end up getting charges.
As I said, this is one of the most complex topics in chemistry.
People have so much trouble with it.
So I urge to maybe check out this video again, watch it from the beginning, make sure you
really understand it before you move on.
And once you're good with this stuff, go on to the next video.