Understanding Changes in State (Grade 7, Unit C: Heat and Temperature)

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Understanding Changes in State (Grade 7, Unit C: Heat and Temperature) by Mind Map: Understanding Changes in State (Grade 7, Unit C: Heat and Temperature)

1. Common Misconceptions

1.1. Chemical composition of matter changes during phase change

1.1.1. When a substance goes through a phase change the actual particles that make it up do not change even though the substance you are left with looks different.

1.1.2. Ex) When water boils, H2O particles make up the steam not O2 particles as is commonly believed.

1.1.3. Aydeniz, M., & Kotowski, E. (2012). What Do Middle and High School Students Know about the Particulate Nature of Matter after Instruction? Implications for Practice. School Science And Mathematics, 112(2), 59-65

1.2. mass of substance changes during phase change

1.2.1. When a substances experiences a physical change, the particles do not grow or shrink in the process, they only gain or lose free space. (conservation of mass)

1.2.2. Ex) When aluminum is melted to make pop cans, there is the exact same number of aluminum particles in the solid raw metal as in the liquid processed metal and they are the same size and shape. The only things removed are impurities like dirt etc.

1.2.3. Aydeniz, M., & Kotowski, E. (2012). What Do Middle and High School Students Know about the Particulate Nature of Matter after Instruction? Implications for Practice. School Science And Mathematics, 112(2), 59-65

1.3. heat and temperature are the same

1.3.1. Heat is a measure of total thermal energy (intensity) in a substance while temperature is a measurement of the total heat content of a substance.

1.3.2. Ex) When different amounts of heat are gained and lost from the same metal rod these amounts are combined, the total it gives us is the temperature reading if the metal.

1.3.3. Kesidou, S., & Duit, R. (1993). Students' Conceptions of the Second Law of Thermodynamics--An Interpretive Study. Journal Of Research In Science Teaching, 30(1), 85-106

1.4. particles present in solids do not move

1.4.1. Although solids have a constant shape and are rigid, the particles that make them up still exhibit movement in the form of vibration.

1.4.2. Ex) Liquid water and gaseous water vapor both take the shape of their containers while ice is rigid and stiff. However if you freeze a container of water, the microscopic particles in the container still have small spaces between them allowing them to vibrate rapidly.

1.4.3. Kesidou, S., & Duit, R. (1993). Students' Conceptions of the Second Law of Thermodynamics--An Interpretive Study. Journal Of Research In Science Teaching, 30(1), 85-106

2. Key Concept: Particle Theory of Matter

2.1. Building off of prior concept knowledge (Gov AB PoS)

2.1.1. Grade 2 Topic A: Exploring Liquids

2.1.1.1. Demonstrate an understanding that liquid water can be changed to other states, ie: water to ice, ice to water, water to steam, steam to water

2.1.1.2. Predict whether an open or closed dish of water will evaporate.

2.2. Building knowledge for future use (Gov AB PoS)

2.2.1. Grade 8: Unit A Mix and Flow of Matter

2.2.1.1. Investigate and compare the properties of gases and liquids; and relate variations in their viscosity, density, buoyancy and compressibility to the particle model of matter

2.2.2. Science 10: Unit A Energy and Matter in Chemical Change (Nature of Science Emphasis)

2.2.2.1. Describe the basic particles that make up the underlying structure of matter, and investigate related technologies

2.3. Outcomes for STS and Knowledge (Gov AB PoS)

2.3.1. Distinguish between heat and temperature; and explain temperature, using the concept of kinetic energy and the particle model of matter

2.3.1.1. From Armstrong, Bocknek, Edwards, Grace, & Zike, 2008

2.3.1.1.1. Matter is anything that takes up space and has mass. The particle theory of matter says that all matter is made up of tiny particles. The particles are always moving, have space between them, and are attracted to one another. The energy of motion is called kinetic energy. Temperature is a measure of the average kinetic energy of the particles that make up an object or a substance.

2.3.1.1.2. The concept that all matter is made of particles is called the particle theory of matter. The important points of the particle theory of matter are listed here. All matter is made up of tiny particles. These particles are always moving—they have energy. There are spaces among particles. There are attractive forces between the particles. The particles of one substance differ from the particles of other substances.

2.3.2. Describe the effect of heat on the motion of particles; and explain changes of state, using the particle model of matter

2.3.2.1. From Armstrong et. al 2008

2.3.2.1.1. The three common states of matter are solid, liquid, and gas. The particle theory explains the states of matter. Matter in any state will expand upon warming and contract upon cooling.

2.3.2.1.2. A solid is the form of matter that has a fixed shape. The shape of a solid will not change when you put it into a container or place it on a table. A solid also has a constant volume. You could try to press on it but its volume would not change. You might be able to change the shape of a solid such as bending a piece of plastic. You might be able to squeeze air bubbles out of something like a sponge, but you are not actually changing the volume of the solid itself.

2.3.2.1.3. A liquid has no shape of its own. When you pour a liquid into a container, it takes the shape of the container and forms a flat surface in the container. Liquids also have an unchanging volume as long as the temperature does not change. You can exert pressure on the liquid but its volume will remain almost exactly the same. You might sometimes think you have compressed a liquid but you probably just squeezed out air bubbles.

2.3.2.1.4. A gas has no shape and no volume of its own. A gas takes the shape of any container and completely fills the container. Gases can easily expand or contract to fit the volume of any container.

2.3.2.1.5. The melting of ice and the condensing of water vapour are called changes of the state of water. All substances can exist as solids, liquids, or gases. The gaseous form of water is often called vapour. However, for most substances, scientists use the term “gaseous state” instead of vapour. The change from any of the three states to any other state is called a change of state. Each change of state has a specific term that describes that change. Melting is the change from the solid state to the liquid state. Freezing is the change from the liquid state to the solid state. Evaporation is the change from the liquid state to the gaseous state. Condensation is the change from the gaseous state to the liquid state. Sublimation is the change from the solid state to the gaseous state. Deposition is the change from the gaseous state to the solid state.

2.3.2.1.6. As you add more energy in the form of heat, the kinetic energy of the particles increases and the temperature increases. Eventually, you reach a temperature at which the kinetic energy of the particles is great enough to break the attractive forces, or springs, that are holding the particles together. This temperature is the melting point of the substance. As the particles break away from one another and have enough energy to slide past each other, the substance becomes a liquid. As a liquid is heated, the particles gain kinetic energy. Eventually, many particles have enough energy to break away from the attractive forces of the other particles and escape from the surface of the liquid. These high- energy particles are now in the gaseous state.

2.4. Sources Used: Armstrong, T., Bockneck, J., Edwards, l., Grace, E., & Zike, D.(2008). Chapter 5 Scientists use the particle theory of matter to describe temperature in Karner, J., Shortt, C., Howard, C., & Hobberlin, C. (Eds.), Discovering Science 7 (pp. 134-171). Whitby, ON: McGraw-Hill Ryerson