Science 7: Unit C – Heat and Temperature Topic 3: The Particle Model of Matter

The Particle Model A model is a simple theory or explanation for how the world works. A model is a simple theory or explanation for how the world works. The particle model of matter explains what matter is and how it acts. The particle model of matter explains what matter is and how it acts. The Model: 1. All substances are made of tiny particles too small to be seen. 2. These particles are always moving. 3. These particles have spaces between them. 4. The faster the particles move in the substance, the higher the temperature of the substance.

What is Matter? (And what it isn’t) Matter is anything in the universe that takes up space (it has to have a volume) and has mass. Matter is anything in the universe that takes up space (it has to have a volume) and has mass. Energy is not matter. You cannot weigh a beam of light, and heat doesn’t take up any room. Energy is not matter. You cannot weigh a beam of light, and heat doesn’t take up any room.

How do the particles move? Solids: The particles are stuck in place and can only vibrate/shake and spin. Solids: The particles are stuck in place and can only vibrate/shake and spin. Liquids – The particles have more freedom and can slide around each other. Liquids – The particles have more freedom and can slide around each other. Gases – The particles are completely free from each other and float freely through space. Gases – The particles are completely free from each other and float freely through space.

What is Energy? Energy is something that allows for changes to occur. These changes could include temperature, speed, or shape. The more energy an object has, the more it can change itself and the world around it. Energy is something that allows for changes to occur. These changes could include temperature, speed, or shape. The more energy an object has, the more it can change itself and the world around it. For example, a baseball lying on the floor has little energy and cannot do very much. A thrown baseball has much more energy and if it hits something (like a player) can cause some very unpleasant changes. For example, a baseball lying on the floor has little energy and cannot do very much. A thrown baseball has much more energy and if it hits something (like a player) can cause some very unpleasant changes.

The Movement of Energy Energy moves when there is a difference in the amount of energies between two objects. Energy moves when there is a difference in the amount of energies between two objects. Energy ALWAYS moves from an area/object with higher energy to an area of lower energy. Energy ALWAYS moves from an area/object with higher energy to an area of lower energy. Eg. A child places his hand on a hot iron. Which has more energy? Where will the energy go? Eg. A child places his hand on a hot iron. Which has more energy? Where will the energy go?

How is energy measured? Energy is actually pretty hard to measure directly. Energy is actually pretty hard to measure directly. There are two units for energy given: There are two units for energy given: 1. Calorie – is the amount of energy needed to heat one kilogram of water one kelvin (or one degree celsius). 2. Joule – is the amount of energy needed to move an object of weight of 1 N one metre.  In science, the joule is the preferred unit. The Calorie is still used to measure energy in foods.

Temperature and Thermal Energy Temperature represents the AVERAGE thermal energy of an object. Temperature represents the AVERAGE thermal energy of an object. Thermal energy represents the TOTAL heat energy in an object. The amount of thermal energy an object depends on two things: Thermal energy represents the TOTAL heat energy in an object. The amount of thermal energy an object depends on two things: 1. The energy the particles have (measured by temperature) 2. The total number of particles in the object. (represented by mass)

Example A 250 ml cup of steaming coffee has a recorded temperature of 65°C. Its total amount of thermal energy is 64 kJ. A 250 ml cup of steaming coffee has a recorded temperature of 65°C. Its total amount of thermal energy is 64 kJ. A 1800 L swimming pool has an average temperature of 25°C. However, because there are so many more water particles than in a cup of tea the total energy is kJ. A 1800 L swimming pool has an average temperature of 25°C. However, because there are so many more water particles than in a cup of tea the total energy is kJ.

The Law of Conservation of Energy Energy can NEVER be created or destroyed. It can only be changed from one kind to another or passed from on object to another. Energy can NEVER be created or destroyed. It can only be changed from one kind to another or passed from on object to another. Eg. Photosynthesis: Light energy from the sun is transferred to a tree and changed from light energy to chemical energy (sugar). Eg. Photosynthesis: Light energy from the sun is transferred to a tree and changed from light energy to chemical energy (sugar).