Temperature depends on particle movement Chapter 4.1 Temperature and Heat Temperature depends on particle movement Chapter 4.1
How Does Matter Change? Put ice cube in beaker and place it on a hot plate. How will the ice cube change? - it will melt into water - it will evaporate and boil into water vapor What stays the same when the ice cube undergoes these changes? - the molecules remained water How is energy related to these changes? - raises the temperature and produces the change in physical state
Matter is made of moving particles Object in motion has kinetic energy All matter is made of atoms All atoms move All objects have kinetic energy Your chair has some amount of energy Explain
Kinetic Theory of Matter States that all of the particles that make up matter are constantly in motion. All matter has kinetic energy Solid - particles are held tightly together but are always in motion Liquid – particles slide by one another and are always in motion Gas – completely free to move around and are always in motion Concrete are not free to move around very much. The vibrate back and forth in the same position and are held tightly by the force of attraction. Ware in a pool moves around freely, constantly sliding around and tumbling over each other as they move. Gas moves around at high speed, they might collide with each other but otherwise they do not interact.
Temperature Particles move at different speeds Not possible to know the KE of each particle, but the average KE can be determined Is the average KE of all the particles in an object If an object has high temperature the particles are moving fast If an object has low temperature the particles are moving slow As temperature rises KE increases Temperature
Temperature continued How is temperature measured? Thermometer – instrument to measure temperature through a regular variation of some physical property of the material inside of the thermometer Liquid expands or contracts Change in temperature is measured in degrees Equal spaces between two points
Temperature scales Freezing point of pure water 32 degrees Fahrenheit Developed in 1700 by Gabriel Fahrenheit 0 degrees Celsius Developed in 1740 by Anders Celsius Boiling Point of pure water 212 degrees Fahrenheit 100 degrees Celsius
Thermal Expansion Property that makes liquid filled thermometers work Affects many substances not just alcohol and liquid mercury All gases, many liquids and most solids expand when temperature increases Construction Engineers need to plan for this St Louis Arch is good example Page 108 for examples