- [Instructor] Most of what we've talked about so far
has been atoms in isolation.
We have thought about the number
of electrons and protons and neutrons
and the electron configuration of atoms.
But atoms don't just operate in isolation.
If that were the case, the whole universe including us
would just be a bunch of atoms drifting around.
What begins to be interesting is
how the atoms actually interact with each other.
And one of the most interesting forms of interaction is
when they stick to each other in some way shape or form.
And this sticking together of atoms is
what we are going to study in this video.
Another way to talk about it is, how do atoms bond?
Now as we will see, there are several types of bonds
and it's really a spectrum.
But let's just start with what I would consider
one of the more extreme type of bonds.
And to understand it, let's get a periodic table of elements
out right over here.
So let's say that we are dealing with a group one element.
Let's say sodium right over here.
What's interesting about group one elements is
that they have one valence electron.
If we want to visualize the valence electrons
for, say, sodium we could do it
with what's known as a Lewis dot structure
or a Lewis electron dot structure,
sometimes just called a dot structure for short.
But because a neutral sodium has one valence electron,
we would just draw that one valence electron like that.
Now let's go to the other end of the periodic table
and say, look at chlorine.
Chlorine is a halogen.
Halogens have seven valence electrons
so chlorine's valence electrons would look like this.
It has one two three four five six seven valence electrons.
And so you could imagine chlorine would love
to get another electron
in order to complete its outer shell.
And we've also studied in other videos these atoms,
these elements at the top right of the periodic table
which are not the noble gases,
but especially the top of these halogens,
things like oxygen, nitrogen.
These are very electronegative.
They like to pull electrons, hog electrons.
And so what do you think is going to happen
when you put these characters together?
This guy wants to lose the electrons
and chlorine wants to gain an electron.
Well, maybe the chlorine will take an electron
from the sodium.
On a real chemical reaction,
you would have trillions of these
and they're bouncing around
and different things are happening
but just for simplicity,
let's just imagine that these are the only two.
And let's imagine that this chlorine is able
to nab an electron from this sodium.
So what is going to happen?
This sodium is then going to become positively charged,
'cause it's going to lose an electron.
And then the chlorine, the chlorine is now going
to gain an electron.
So it's going to become a chloride anion.
Anion is a negative ion.
It's a sodium cation, a positive ion.
Ion means it's charged.
And now it's a chloride anion.
So it has the valence electrons that it had before
and then you could imagine
that it gains one from the sodium.
And now it has a negative charge.
Now what do we know about positively charged ions
and negatively charged ions?
Opposites attract.
Coulomb forces.
So these two characters are going
to be attracted to each other,
or another way to think of it,
they're gonna stick together,
or another way you could think about it,
they are going to be bonded.
And they will form a compound of sodium chloride.
And notice the whole compound here is neutral.
It has a plus one charge for the sodium,
a negative one charge for the chloride,
but taken together it is neutral
because these are hanging out together.
And this type of bond between ions,
you might guess what it's called.
It is called an ionic bond.
Ionic bond.