10.1 Temperature, Thermal Energy, and Heat The kinetic molecular theory explains that all matter is made up of tiny particles. These atoms and molecules are constantly in motion. Kinetic energy is energy due to motion. http://www.brainpop.com/science/energy/formsofenergy/ Solids, liquids, and gases behave differently according to the kinetic molecular theory. See page 424 (c) McGraw Hill Ryerson 2007

10.1 Temperature, Thermal Energy, and Heat The particles of a substance move differently for different states. In solids, particles vibrate slightly but do not change position. In liquids, particles vibrate more and move around within a set volume. In gases, particles vibrate greatly and move around to take all volume available. Solids, liquids, and gases behave differently according to the kinetic molecular theory. See page 424 (c) McGraw Hill Ryerson 2007

The movement of particles is what we measure as temperature. Temperature is the measure of the average kinetic energy of all particles in a sample A cup of tea feels hot because average kinetic energy of all its particles is more than your hand As the particles’ average kinetic energy increases, the temperature of a sold, liquid, or gas will also increase. Particles in a glass of cold water move slower and have less kinetic energy than particles in a cup of hot water Measured in degrees Fahrenheit (°F), degrees Celsius (°F), or Kelvin (K). scale. Celsius scale ws named after Swedish astronormer Anders Celsius (1701-1744). First used in 1745. used around the world. Based on two fixed points: freezing point of water (0C) and BP. 1848 William Thompson of Scotland proposed temp scale bases on absolute zero, temp at which particles have no kinetic energy. (c) McGraw Hill Ryerson 2007

Since temperature is a way of measuring the average energy of the particles in an object, it does not change when the size of the object changes. (c) McGraw Hill Ryerson 2007

Thermal energy = all kinetic energy + all potential energy Thermal energy is the total energy of all the particles in a substance. Thermal energy = all kinetic energy + all potential energy KE is the energy of movement. PE is the stored energy due to its position or state = how much the particles vibrate, and therefore how much space they take up. Kinetic ( greek kinetikos – to put in motion) (c) McGraw Hill Ryerson 2007

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Thermal Energy The amount of thermal energy depends on the size of the object - the larger the object, the more moving particles it contains. (c) McGraw Hill Ryerson 2007

Heat Heat is the amount thermal energy that transfers from an area of higher temperature to an area of lower temperature. Ex. When you cup your cold hands around a mug of hot chocolate, heat is transferred from the mug to your hands. http://www.brainpop.com/science/energy/heat (c) McGraw Hill Ryerson 2007

Thermal Energy Transfer Conduction is the transfer of heat by direct contact. Heat is transferred from higher temperature, (higher kinetic energy), to lower temperature, where particles have lower kinetic energy. For example, a cold spoon warms when placed in a cup of hot coffee. Thermal conductors transfer heat easily, while insulators do not. See pages 427 - 430 Take the Section 10.1 Quiz (c) McGraw Hill Ryerson 2007

Thermal Energy Transfer Convection is the transfer of heat in fluids (liquids and gases). Convection is the movement of heat from hot to cold within a fluid, or the movement of hot liquid to an area of cold liquid. Because there is a density difference, hot fluid (low density) moves to cold. This is how convection currents form. See pages 427 - 430 Take the Section 10.1 Quiz (c) McGraw Hill Ryerson 2007

Thermal Energy Transfer Radiation is the transfer of radiant energy by waves through space. What we feel as heat is generally called infrared radiation. Earth’s interior thermal energy comes from the core, plus some radioactive element decay . See pages 427 - 430 Take the Section 10.1 Quiz (c) McGraw Hill Ryerson 2007

Electromagnetic Radiation (EMR) – radiates outward in all directions. Anything with temperature more than absolute zero radiates heat. The heat is transferred when material absorbs radiation (which increases temperature or causes a substance to melt or evaporate). Electromagnetic Radiation (EMR) – radiates outward in all directions. Infrared (IR) - feel heat when sitting next to a campfire Visible light Solar Radiation – visible, IR and other. (c) McGraw Hill Ryerson 2007

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Check your Understanding Checking Concepts 1-5 p 435 (c) McGraw Hill Ryerson 2007