2. THE STATES OF MATTER

Transcription

1 2. THE STATES OF MATTER 2.1. THE THREE STATES OF MATTER Every substance can take on several distinct forms called phases or states of aggregation of matter. Four states of matter are observable in everyday life: solid, liquid, gas, and plasma. There are several other states (liquid crystal, superfluid, Bose Einstein condensates ) but these only occur in extreme situations such as ultracold or ultradense matter. Substances can move from one phase to another if certain physical conditions, like temperature, change. Example: Each state has different macroscopic 1 properties: SOLID LIQUID GAS Fixed volume and shape Assumes the shape of the bottom part of the container they occupy, with a free surface at the top Assumes the shape and whole volume of its container Not easily compressible 2. Not easily compressible Easily compressible Does not flow easily Flows quite easily Flows very easily Both gases and liquids are called fluids due to their capacity to flow. 1 Macroscopic It means large enough to be visible to the naked eye. 2 When you compress something, you measure out a certain amount of material and force it into a smaller volume. Copy in your notebook the diagram that shows the macroscopic property of each state and learn it. Write the new vocabulary and search the meaning. Go to this youtube video and answer the questions at the end of the unit. Click and do the test:

2 2.2. THE KINETIC THEORY The kinetic particle theory explains the properties of the different states of matter. The particles in solids, liquids and gases have different amounts of energy. They are arranged differently and move in different ways. The table below summarises the arrangement and movement of the particles in solids, liquids and gases, and shows simple diagrams for the arrangement of the particles. Diagram of particle arrangement and movement Solids The table shows some of the properties of solids and why they are like this. Solids have a fixed shape and cannot flow Solids cannot be compressed or squashed The particles cannot move from place to place The particles are close together and have no space to move into Liquids The table shows some of the properties of liquids and why they are like this. Liquids flow and take the shape of their container Liquids cannot be compressed or squashed The particles can move around each other The particles are close together and have no space to move into Gases The table shows some of the properties of gases and why they are like this. Gases flow and completely fill their container Gases can be compressed or squashed The particles can move quickly in all directions The particles are far apart and have space to move into

3 Draw in your notebook a diagram of particles for solids, liquids and gases according with the Kinetic theory and describe their properties STATE CHANGES Substances can exist as a solid, liquid or gas. Converting from one state to another usually involves heating or cooling. Heat must be supplied to a substance for it to melt, evaporate or boil. For example, you need to heat ice to melt it, and you need to heat water to make steam. Heat must be removed from a substance to condense or freeze it. In other words, the substance must be cooled down. Under certain conditions, some solids turn straight into a gas when heated. This process is called sublimation. A good example is solid carbon dioxide, also called dry ice. At atmospheric pressure, it turns straight into gaseous carbon dioxide. Liquid carbon dioxide can only exist under high pressure, such as in fire extinguishers. Iodine also sublimes - it turns directly from shiny purple-black crystals to a purple vapour when warmed up. Changing the pressure A gas will also liquefy (turn into a liquid) if its pressure is increased enough. This is because the particles are moved close enough for bonds to form between the particles. Gas cylinders used for camping stoves and barbecues contain liquefied petroleum gas (LPG) under high pressure. As soon as the pressure is released, the liquid turns back to a gas. Draw in your notebook a diagram with the name of the changes of state and learn them. Questions about the video: What is matter? What are the five states of matter that are showed in the video? Matter needs a temperature to be in Bose Einstein condensate state. Describe the solid characteristic according to the video and the Kinetic Theory. Gas particles has big space between them and kinetic energy. Plasma is the state in the universe.

4 Across: 2. Air is an example of a. 4. in the sky are made from water vapor. 6. take the shape of their containers. 7. can be a liquid solid or gas depending on the temperature. 9. There are three basic states of. Down: 1. is the amount of matter an object has. 3. have a definite shape and volume. 5. is the amount of space that matter takes up. 8. All matter is made up of tiny particles called..

5 2.4. WORKSHEET. Answer the next question in your notebook: 1. What are the 3 more common forms of matter on the earth? a. solid b. plasma c. liquid d. gas 2. This state of matter has no definite shape or volume. a. plasma b. gas c. liquid d. solid 3. A solid is a state of matter that has a definite volume, but not a definite shape. a. True b. False 4. A substance which takes the shape of its container and has a definite volume is a a. solid b. liquid c. gas d. crystal 5. Particles of matter that move faster (like in a gas) have more of what? a. energy b. mass c. color d. weight 6. True or false? The particles of a gas are packed tightly together. 7. True or false? Gases are hard to compress. 8. True or false? Liquids are easy to compress. 9. The particles in a liquid are a. closer together than in a solid and further apart in a gas b. are spaced the same as in solids and gases c. closer than in gases but further apart in solids d. none of the above 10. The process by which liquid changes into a gas is called 11. When a solid changes to a liquid, what is it called? 12. When a gas reaches its condensation point, what does it become? 13. What is it called when a solid changes directly into a gas? 14. When solids reach their melting points, what do they become?