SOL 5.4 PART 2 Force, Motion, Energy & Matter NOTEPAGE FOR STUDENT Page 1 Phases of Matter We have learned that everything on Earth is made up of matter. We have also learned that all matter is made up tiny particles called atoms. These tiny particles are always in motion. Based on how fast or how slow these tiny particles are moving, matter can be divided into three categories or phases: solid, liquid, and gas. In a solid, atoms are packed tightly together and move very slowly. In fact, they do not flow at all: they simply vibrate back and forth. Because the atoms in a solid are so tightly packed, solid matter holds its shape and cannot be easily compressed. Solids also have a definite volume. Your pencil is an example of solid matter. In a liquid, the atoms are spaced farther apart and move faster. They are also able to flow or slip past each other. Because of this, liquids do not hold their shape but take the shape of the container in which they are placed. Even though liquids do not hold a definite shape, they do have a definite volume and cannot be easily compressed. The milk you drink at lunch is an example of liquid matter. In a gas, the atoms move around very quickly and flow easily. As they move, they move away from each other to fill any container they are placed in. Because of the space between the molecules, gases do not have a definite volume and they can be compressed. Have you ever sprayed air freshener in a room? Soon the smell fills the entire room and even travels into nearby rooms. This is an example of how gas atoms travel quickly to fill up an area. ©2012 SOL 5.4 PART 2 Force, Motion, Energy & Matter NOTEPAGE FOR STUDENT Page 2 Phases of Matter Did you know that changes in temperature can cause matter to change from one phase to another? It’s true! Let’s investigate with water. Water’s most common phase is liquid. In its liquid form, water molecules move around slowly, sliding past each other. As the temperature drops or decreases, the water molecules gradually slow down. Eventually they stop moving and simply vibrate back and forth. At this point ice is formed, the solid phase of water. If the temperature is allowed to increase, the molecules will once again begin to vibrate faster and faster. Eventually they will begin moving and sliding past one another. At this point the solid phase (ice) changes (melts) back into the liquid phase we know as water. If the temperature continues to rise, the molecules in the liquid begin to move faster and faster. Eventually they move so fast they change into a gas, or water vapor, and rise into the air. ©2012 .