In the liquid state, a substance will take the shape of any vessel, a jug or cup, for example, into which it is put because the molecules can move enough to allow it to do this. With even more energy, the molecules move very quickly, and the bonds between them are no longer strong enough to hold them together. This is matter in the state of a gas. Gases can fill up, or distribute themselves equally within, anything into which they are placed. The bonds between the molecules are so weak that they can move far enough away from each other to do this.
Matter changes state when the molecules change speeds and the bonds are weakened or strengthened.
All substances have freezing points and boiling points . These are temperatures at which substances change their state. The higher the temperature, the faster the molecules move. At a certain temperature, the molecules of a substance will have the amount of energy necessary for the substance to change state. Let's use an ice cube as an example, which is frozen water.