Ionic vs. Molecular

In this video we will look at

ionic

compounds versus

molecular

compounds, also known as covalent. We will learn how to differentiate them according to their formulas and then we will see some important differences between them. So how can you tell if something is

ionic

or

molecular

? Well, it depends on the elements that may arise. So, ionic compounds are made of metals and non-metals, while molecular compounds, also known as covalent compounds, are made of only non-metals. Let's do a couple of practice problems to work on this. You will need a periodic table to do this, here is the one I am using, I left out many elements because they are not important.

But the important thing is this great thick staircase that divides the periodic table into two parts. On this side of the ladder are the medals and on this side of the ladder are the non-metals. Well, here are a couple of examples. The first, sulfur dioxide, where are the elements that make it up? It is composed of sulfur and oxygen, both non-metals, which means that sulfur dioxide (SO2) is a molecular compound. Sodium chloride is composed of sodium, a metal, and chlorine or chloride, which is a nonmetal. Sodium chloride is an ionic compound. Alright, H2O is made of hydrogen and oxygen.

Now, you might think that hydrogen is a metal because it is on this side of the periodic table, that's fine and understandable if you do. But hydrogen is an exception, although it is on this side of the periodic table, it is actually a non-metal, it is the only exception. So hydrogen and oxygen are actually non-metals, which means that water H2O is a molecular or covalent compound. Well, copper(II) fluoride, the copper is here and the fluorine or fluoride is here, metal, non-metal, so this thing is ionic. Well, let's look at some more complicated examples. So far, we've only looked at compounds that have two elements, but there are many compounds that have more than two elements, okay?

Thus, propanol, for example, is composed of carbon, hydrogen and oxygen. However, all three are non-metals, so it is still a molecular or covalent compound even though it has many non-metals, okay? Don't be confused by that. Here is another example. Lithium nitrate has lithium, which is a metal, but it also has nitrogen and oxygen, which are non-metals. So it still has that metal and non-metal thing, so it's an ionic compound even though it has two non-metals and the same goes for sodium sulfate. It has sodium, a metal, and two non-metals, sulfur and oxygen, but metal and non-metal means it is ionic.

Now, lithium nitrate and sodium sulfate are actually special types of ionic compounds because they contain two different nonmetals. They are what are called polyatomic ionic compounds and if you want to learn more about them, I have videos about them. Now we can look at a chemical formula, classify them and decide if something is ionic, 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 them right now. So a really important difference is how the atoms of these compounds are held together.

In molecular or covalent compounds, the atoms that form them stay together because they share electrons. This is what I mean. Water, H2O, is a very common molecular compound. It is made up of one oxygen and two hydrogens and these lines between the atoms show that they are connected and mean that they are connected because they share electrons. That's how I like to think about it. It's like Oxygen and Hydrogen have these little hands and the hands are joined together, it's like they are holding hands and holding hands because they are both trying to hold on to a pair of electrons that I have drawn here. red.

You have oxygen and hydrogen connected because they hold and share these electrons here, that's what makes the atoms connect and stay together in a molecular or covalent compound, okay? Now, on the other hand, in ionic compounds, the atoms are not so kind to each other: they do not share. Atoms are held together in an ionic compound because one atom steals electrons from another, so electrons are 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 of sodium and chlorine and they're just hanging out here.

Now, to keep these two guys together, here's what happens. The first thing that happens is that the chlorine reaches out its greedy hand and grabs an electron from the sodium, okay, and takes it away. So now chlorine has an extra electron and sodium has lost one of its electrons. This means that chlorine now has a negative charge because it has a new electron and sodium, because it had one of its electrons stolen, now has a positive charge. Now we have a positively charged ion here and another negatively charged ion here. What do oppositely charged things like to do?

They like to join together, they stick together, they attract each other like magnets. So now we have one positively charged thing and one negatively charged thing. These arrows show how they will stick together and we will end up with the two atoms stuck together because they are oppositely changed and that is what holds ionic compounds together. So in covalent or molecular compounds, atoms are stuck together because they share electrons with each other. In ionic compounds, the atoms are stuck together because one has stolen electrons from the others, given them opposite charges, and then those opposite charges have attracted each other like magnets.

This is one of the differences between ionic and molecular compounds. Here's one more. So another big difference is what these compounds would actually look like 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 group of atoms that are stuck together in a group. This is what I mean. So sugar is a very common type of covalent compound and it's made of molecules, where I have these atoms here stuck together in a group: 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 came together and formed a clump here, okay?

But the important thing here is that these molecules are individual groups of atoms that then come together to form things. On the other hand, ionic compounds are not made of groups of atoms like molecules. They are made of what we call lattice structures and this is 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 make up sugar. You just have the sodium and chloride atoms stuck together in this very organized box shape.

This is what a lattice structure is. There are no individual groups of sodium chloride like there are individual groups of sugar, but all the atoms are stuck together in this very regular way. Now, a big important difference between covalent or molecular elements and ionic elements is what happens when they dissolve in water. These types simply separate into molecules, while individual atoms separate when an ionic compound dissolves in water, but we're getting a little ahead of ourselves here. If you are interested in other differences between these, check out the videos I have on physical properties and what happens when ionic and molecular compounds dissolve.