Changing States of Matter

1. Changing States of Matter

2. PART ONE

3. What states of matter do you know?

5. We are going to analyse just three of them, the main ones: Solid Liquid Gas

6. Now, name at least two examples for each of the three states.

7. Materials can be changed from one state to another by adding ...

8. And what's the easiest energy around? energy

9. Probably heat!

10. But matter changes if you take away heat from it, too.

11. Adding energy is HEATING Taking away energy is COOLING

12. Heating Heat can change solids into liquids or gases. Most solids melt into liquid when they are heated. A liquid evaporates into a gas when it is heated. Let's see what happens to water.

13. If ice (solid) is heated, it changes to water (liquid). This change is called melting. Water (liquid) can change to water vapour (gas). This is called evaporation. If water (liquid) is heated until it boils, it changes to water vapour (gas) very quickly.

14. Cooling Cold can change gases and liquids. Gases may change to liquids. This change is called condensing. Liquids may change to solids. This change is called freezing.

15. Cooling If water vapour (gas) is cooled, it changes to water (liquid). This change is called condensing. If water (liquid) is cooled, it changes to ice (solid). This change is called freezing.

17. Different solids melt at different temperatures, some high, some low. These are called their...

18. melting points.

19. Different liquids freeze at different temperatures.

20. Scientists use something called a freezing point to measure when that liquid turns into a solid

21. Finally, different gases turn to liquids at different condensation points.

22. Sublimation: · This is when a solid, on heating, directly changes into a gas without melting, AND the gas on cooling re-forms a solid directly without condensing to a liquid. They usually involve just a physical change BUT its not always that simple!

25. Chemical vs. Physical Changes It is important to understand the difference between chemical and physical changes. The two types are based on studying chemical reactions and states of matter. Physical changes are about energy and states of matter. Chemical changes happen on a molecular level.

26. When you melt an ice cube you have forced a physical change (adding energy). That example caused a change in the state of matter. You can cause physical changes with forces like motion, temperature, pressure.

27. Now, we know matter can change from one state to another. But what happens inside matter when such changers occur?

28. Pressure

29. Let's start it all over agian... What is a solid? Solids are usually hard because their molecules have been packed together. The closer your molecules are, the harder you are. Solids also can hold their own shape. A rock will always look like a rock unless something happens to it.

30. Even when you grind up a solid into a powder, you will see little tiny pieces of that solid under a microscope. Liquids will move and fill up any container. Solids like their shape.

31. In the same way that a solid holds its shape, the atoms inside of a solid are not allowed to move around too much. This is one of the physical characteristics of solids.

33. Atoms and molecules in liquids and gases are bouncing and floating around, free to move where they want. The molecules in a solid are stuck. The atoms still spin and the electrons fly around, but the entire atom will not change position.

37. The second state of matter we will discuss is a liquid. Solids are hard things you can hold. Gases are floating around you and in bubbles. What is a liquid? Water is a liquid.

38. Liquids are an in-between state of matter. They can be found in between the solid and gas states. They do not have to be made up of the same compounds. If you have a variety of materials in a liquid, it is called a solution.

39. One characteristic of a liquid is that it will fill up the shape of a container. It fills the bottom first because of gravity. The top part of a liquid will usually have a flat surface. That flat surface is because of gravity too.

40. A special force keeps liquids together. Solids are stuck together and you have to force them apart. Gases bounce everywhere and they try to spread themselves out. Liquids actually want to stick together.

41. There will always be the occasional evaporation where extra energy gets a molecule excited and the molecule leaves the system. Overall, liquids have cohesive (sticky) forces at work that hold the molecules together.

42. A special force keeps liquids together. Solids are stuck together and you have to force them apart. Gases bounce everywhere and they try to spread themselves out.

43. Liquids actually want to stick together. There will always be the occasional evaporation where extra energy gets a molecule excited and the molecule leaves the system. Overall, liquids have cohesive (sticky) forces at work that hold the molecules together.

45. PART TWO: AFTER THE SIMULATION

46. All matter is made up of tiny particles called atoms. These particles are always moving and are attracted to one another. A material's state of matter is determined by the movement of the particles. The more energy they have, the further apart they want to get from each other.

47. Solids A solid is the state of matter that has the least amount of energy. It has a definite shape and volume. The particles of a solid are packed close together. The particles of a solid are moving, vibrating back and forth, but they don't have enough energy to break away from one another.

49. A liquid is matter that has a definite volume but no definite shape. A liquid takes the shape of its container but keeps the same volume. The particles in a liquid move more freely than those in a solid, but do not have enough energy to move apart from one another