 So here we have a water molecule. The hydrogens and the oxygen are covalently bonded. So if we have a few more of these molecules, they interact with each other, and the forces between each molecule are called intermolecular forces. That's what we'll be looking at over the next few videos. So the structure of these molecules as well as the composition determines what intermolecular forces are present, as in how strong they are. And this therefore determines the properties of the material. Properties such as if the material is in its solid phase, liquid phase, or gas phase at room temperature. Intermolecular forces between molecules are how molecules form solids and liquids, how they come together and stay together. And the stronger these intermolecular forces are between each other, the more heat energy is required to weaken these bonds to change phase. Intermolecular forces within a solid are tightly held, while in the liquids they're slightly looser. So for this phase change to occur, we must break some of the bonds that the solid has in order for it to become a liquid. So looking at these things, it makes sense that melting points and boiling points give an indication of the strength of intermolecular forces. So if we have a strong force, more heat energy is required, and therefore we see a higher melting and boiling point in the compound.