Everything that you can see and touch is made up of matter. Even the stuff you can't see or touch, like the oxygen you are breathing now, is made up of matter. Matter mostly exists in one of three forms: solid, liquid, or gas. Solids have their molecules tightly packed together and they hold their shape. The molecules in liquids are a little more spread out and they take the shape of whatever container they are in. Gases are very spread out and are constantly moving. Matter can change phase simply by changing the temperature or pressure in its environment. These temperatures and pressures where a phase change will occur are different for all types of substances. In fact, many compounds are identified by simply verifying the temperature or pressure at which these phase changes occur. As matter shifts to another phase each type phase change has a specific name. We are all familiar with water. We most common think of water as a liquid, but it can be solid in the form of ice and a gas in the form of water vapor. As water moves through all of these phases it changes shape and speed. When matter changes from liquid form to solid form this is called freezing. When a liquid becomes a gas the phase change is called evaporation. When they go in the opposite direction, the names are changed. When a solid becomes a liquid, it is called melting. This is what happens to ice when it gets too hot. When a gas becomes a liquid, this is called condensation. For some reason we think that solids cannot quickly become gases or vice versa, but these are many substances that do this regularly. Dry ice which is carbon dioxide in a solid form often does this at room temperature. When a solid becomes a gas the phase change is called sublimination. When a gas becomes a solid this is called deposition. This commonly happens during the winter months when water vapor turns to ice and makes our roads rough to travel on.
The worksheets include the phases of matter (solid, liquid, gas), forms of substances, the action taken at each phase by the molecules involved. We begin this worksheet section by classifying many different substances on a chart. We move on to exploring the states of matter by using a fun puzzle. We then look at complete changes in phases of these substances. We then move on to drawing the molecules using water as our guide. We describe the shape and movement of the molecules along the way. If you are looking for basic worksheets, scroll down the page a bit.