In this video we're going to look at compounds that are ionic versus compounds that are molecular
also known as covalent.
We will learn how you can tell them apart based on their formulas and then we'll look
at some important differences between them.
So how can you tell whether something is ionic or molecular?
Well it depends on the elements that may come up.
So ionic compounds are made of metals and nonmetals whereas molecular also known as
covalent compounds are made of only nonmetals.
Let's do a couple practice problems to work on this.
You will need a periodic table to do this, here's the one that I'm using, I've left out
a lot of the elements because they're not important.
But what is important is this big thick staircase that divides the periodic table into two parts.
On this side of the staircase are the medals and on this side of the staircase are the
nonmetals.
Okay, so here are a couple examples.
The first one, Sulfur Dioxide, so where are the elements that it�s made of.
It's made up of Sulfur and oxygen, both these are nonmetals, which means that Sulfur Dioxide
(SO2) is a molecular compound.
Sodium Chloride is made up of Sodium, a metal, and Chlorine or Chloride which is a non-metal.
Sodium Chloride is an ionic compound.
Alright now, H2O is made of Hydrogen and Oxygen.
Now you might think that Hydrogen is a metal because it's on this side of the periodic
table, it�s fine and understandable if you do that.
But Hydrogen is an exception, even though it's on this side of the periodic table it�s
actually a non-metal, it's the only exception.
So Hydrogen and Oxygen are actually both nonmetals which means that H2O water is a molecular
or covalent compound.
Okay Copper (II) Fluoride, Copper is here and Fluorine or Fluoride is here, metal, non-metal
so this thing is ionic.
Okay, let's look at a few trickier examples.
So far, we've only look at compounds that have two elements but there are a lot of compounds
out there that have more than two elements, okay?
So Propanol for example is made up of Carbon, Hydrogen and Oxygen.
All three of these are non-metals though so this is still a molecular or covalent compound
even though it has a bunch of nonmetals, okay?
Don't be confused by that.
Here's another example.
Lithium Nitrate has Lithium which is a metal but then it also has Nitrogen and Oxygen which
are both nonmetals.
So it still has that metal, nonmetal thing going on so it's an ionic compound even though
it has two nonmetals and the same thing is true of Sodium Sulfate.
It's got Sodium, a metal, and two nonmetals, Sulfur and Oxygen but metal and nonmetal means
it�s ionic.
Now Lithium Nitrate and Sodium Sulfate are actually special kinds of ionic compounds
because they have two different nonmetals in them.
They are what are called polyatomic ionic compounds and if you want to learn more about
these I've got videos on them.
So now we can look at a chemical formula and we can sort them and we can decide whether
something is ionic or whether it�s molecular or covalent.
So what?
Who cares?
Well there are some very important differences between ionic compounds and molecular compounds.
Let's take a look at some of those right now.
So one really important difference is how the atoms in these compounds are held together.
In molecular or covalent compounds, the atoms that make them up are held together because
they're sharing electrons.
Here's what I mean.
Water, H2O, is a very common molecular compound.
It's made up of one Oxygen and two Hydrogens and these lines between the atoms show they're
connected and they mean that they're connected because they're sharing electrons.
Here's how I like to think about this.
It's like Oxygen and Hydrogen both have these little hands and the hands are joined together,
it�s like their holding hands and they're holding hands because they both are trying
to hold on to a pair of electrons which I've drawn here in red.
You got Oxygen and Hydrogen connected together because they're holding on and sharing these
electrons here, that's what makes atoms connect and stick together in a molecular or covalent
compound, okay?
Now on the other hand, in ionic compounds, atoms aren�t being so nice to each other�they're
not sharing.
The atoms stick together in an ionic compound because one atom steals another atoms electron,
so electrons get stolen, and then opposite charges attract.
Let me show you what I mean.
So Sodium Chloride or NaCl is a very common ionic compound, it's made up of Sodium and
Chlorine and here they are just hanging out.
Now for these two guys to stick together, here is what happens.
The first thing that happens is Chlorine reaches its greedy hand over and grabs an electron
from Sodium, okay, and it pulls it back.
So now, Chlorine has an extra electron and Sodium has lost one of its electrons.
This causes Chlorine to now get a negative charge because it has a new electron and Sodium
because it had one of its electron stolen now it has a positive charge.
So now we have a positively charged ion here and another negatively charged ion here.
What do opposite charged things like to do?
They like to come together, they stick together, they are attracted to each other just like
magnets.
So now, we have a positively charged thing and a negatively charged thing.
These arrows show how they're going to come together and we end up with the two atoms
stuck together because they're oppositely changed and that's what holds ionic compounds
together.
So covalent or molecular compounds, the atoms are stuck together because they're sharing
electrons with each other.
Ionic compounds, atoms are stuck together because one has stolen the others electrons,
it's given them opposite charges and then those opposite charges have attracted just
like magnets.
That is one way that ionic and molecular compounds differ.
Here is one more.
So another big difference is how these compounds would actually look if we could see the atoms
that make them up.
So molecular or covalent compounds are made of molecules, which is a fancy word for a
bunch of atoms that are stuck together in a clump.
Here's what I mean.
So sugar is a very common type of a covalent compound and it is made of molecules, where
I have these atoms here stuck together in a clump-- two Carbons, four Hydrogens and
two Oxygens.
So a grain of sugar would look like this, it would look like a number of different sugar
molecules that have all kind of come together and formed a clump here, okay?
But the big deal here is that these molecules are individual clumps of atoms that then come
together to make stuff.
On the other hand, ionic compounds� they're not made of clumps of atoms like molecules.
They�re made of what we call lattice structures and here's what lattice structures are.
The example I'm going to give you is salt which is Sodium Chloride table salt and the
lattice structures of Sodium Chloride look like this.
Look how different this is from the molecules that makeup sugar.
You just have the Sodium and the Chloride atoms stuck together in this very organized
box-like shape.
This is what a lattice structure is.
There aren�t individual clumps of Sodium Chloride the way there are individual clumps
of sugar, instead all the atoms are stuck together in this very regular shape.
Now one big important difference between covalent or molecular stuff and Ionics is what happens
when they dissolve in water.
These guys just come apart into molecules whereas the individual atoms come apart when
an ionic compound dissolves in water but we're getting a little ahead of ourselves here.
If you're interested other differences between these, check out videos that I have on physical
properties as well as what happens when you dissolve ionic and molecular compounds.