Do Now – Copy and Fill in: Shape Volume Energy/motion of particles Attractive forces among particles Solid Strong forces Liquid More energy than a solid, particles slide past each other Gas Not definite – fills the container

Particle Motion demo Purpose: To understand the relationship between temperature and the motion of particles. A drop of food coloring will be placed into a beaker of cold water, and then one will be placed into a beaker of hot water. Observe and record the motion of the food coloring in each beaker Room temperature ________

Starting temperature: _____ Time (seconds)   Cold Water Starting temperature: _____ Hot Water Starting (0) (observations…how does the food coloring move, be as descriptive as possible)  (observations…how does the food coloring move, be as descriptive as possible) 30 60 (1 min) 120 (2 min) End of class Temperature at end of class: _____ Temperature at end of class: _______

Particle Motion and Energy

Temperature The particles of a substance are always moving. Kinetic energy is energy due to movement. Temperature is the measure of the average kinetic energy of the particles of a substance When the particles move faster, the temperature of an object goes up When the particles move slower, the temperature of an object goes down

Homework Compare the motion and energy of the particles in a beaker of water that is 20 °C and a beaker of water that is 40 °C. Explain the reasoning behind your answer.

Particle Motion and Energy

Thermal energy Particles not only have energy due to their motion (kinetic energy), but they also have energy due to their arrangement and interactions/attractive forces (called potential energy). Thermal energy is the TOTAL energy of all the particles in an object/substance

Objects/substances with more particles will have more thermal energy Ex/ If a beaker of water and a pool both have the same temperature, the pool will have more thermal energy because it has more particles, so it has a higher total energy.

Heat (transfer) Heat is the movement of thermal energy from a warmer substance to a cooler substance. The object transferring thermal energy will lose energy and become cooler, and the object receiving thermal energy will gain energy and become warmer.

Examples of heat transfer A spoon in a cup of hot coffee The coffee transfers thermal energy to the spoon, making the spoon warmer A cup of hot soup in a room The soup transfers energy to the cooler air around it, so the soup becomes cooler An ice cube in your hand You transfer thermal energy to the ice cube, so it gains energy (and will start to melt). You feel cold because you are LOSING thermal energy.