 We are going to place some compounds around this metal plate and then we're going to heat them up. What your task is in this activity is to observe what happens and record the things that melt first and any other changes that you see. Now, earlier we talked about three types of compounds, metallic, ionic and covalent. We're going to look at two ionic compounds, sodium chloride, just put a little here, copper sulfate pentahydrate, a nice, pretty blue. These are two ionic compounds. The third one we're going to put is tin, which is a relatively soft metal. And then we have three covalent compounds. We have naphthalene that we looked at before, sucrose, which is sugar, table sugar. And we have silicon dioxide, better known as sand. I'm going to turn the heat on and I want you to observe what happens. Notice right here the naphthalene is beginning to melt. It looks like a liquid, but observe what happens. As soon as it becomes a liquid, it evaporates. Something that's happening to the sucrose, do you see the smoke coming off the sucrose? Also, notice what's happening to the copper sulfate over on this side. That pretty blue color, the blue's going away and leaving us with a white powder. The sucrose is melting and it's changing colors. Can you see that it's becoming a caramel brown color? Now it's bubbling, see how it's bubbling and it's smoking. So what's happening to the sucrose is that the bonds that make it sugar are actually breaking. It's not evaporating, it's breaking apart and it's becoming carbon dioxide and water vapor. See that smoke coming off? So we're decomposing that sucrose. So the intermolecular forces in this case are stronger than the intramolecular that keeps it as a sugar compound. Here you can see on my toothpick that caramel color. What's happening here to our copper sulfate pentahydrate is the heat is driving the water molecules away. And copper sulfate and hydrous is white. So when all of this, when the heat drives away all the water, we're left with copper sulfate, which is an ionic compound like the sodium chloride we have here. We have sodium chloride and it doesn't seem like it's doing anything. The silicon dioxide, the sand is not melting at all. It's not changing. And the tin doesn't look like much is happening, but if we sort of stir it around you can see that it's actually beginning to melt. Metals have a wide range of melting points. So tin has a very low melting point compared to some metals. And of course our stainless steel tray that we're putting doing all this experiment in is metal and it's not melting. So we can tell the difference between the molecular compounds, the covalent molecular, the ionic have high melting points, the molecular have low melting points, metals have a variety of melting points from a very high melting point to a relatively low melting point like this. Silicon dioxide is a special kind of covalent compound called network covalent. So from this you should see some of the physical properties of covalent, ionic and metallic compounds.