Section 1
Chemical Energy: Energy that matter possess because of its chemical makeup. Where does the energy come from? Movements of the atoms Energy from the force of attraction between Hydrogen and Oxygen Chemical Energy
Chemical bond: Force of attraction between different atoms This attraction binds the atoms together Chemical Energy
Kinetic Energy Energy an object possesses due to its motion Atoms and molecules are in constant motion There is even movement between the atoms in an ice crystal Potential Energy Energy an object has because of its position Ex: Water Figure 2-3 When bonds are formed or broken
All physical and chemical changes involve a change in energy Examples: 1.Wood burns Gives off heat 2.Solid to melt Energy has to be added to make it melt Energy: the capacity to do some type of work such as move an object. Changes in Energy
Law of conservation of energy: In any physical or chemical change, energy can change form but the total amount of energy remains constant Energy can be converted from kinetic to potential energy but it cannot be created or destroyed. Energy
Heat: Total of the kinetic energy of the particles in a sample of matter. Heat is the most common way to transfer energy Chemists keep track of energy transfers by defining the system Energy
System: All of the components that are being studied at a given time. Everything outside of the system is the surroundings Example: Heat pack Page 43 Heat can be transferred from the system (heat pack) to its surroundings (your hands) on a cold day. Heat energy can also be transferred from the surroundings to the heat pack. Energy
Reactions in which heat is transferred from the surroundings into the system are _______________ reactions. Endothermic reactions Therefore, energy is not really “absorbed” it is converted into chemical energy or some other form of energy. Energy
Temperature: Measure of the average kinetic energy of the random motion of particles in a substance. Temperature indicates how hot or cold something is. To increase the temperature of water, energy has to be transferred to the water As the temperature of the water increases the water molecules move and increase their average kinetic energy Energy transfer as Heat
Specific Heat Capacity: Amount of heat energy required to raise the temperature of a 1 gram substance by 1 Kelvin The SI unit for energy is joule Specific heat capacity is J/g x K Table 2-2 has specific heats for some elements Specific Heat
E = mc 2 E = energy M = mass C = the speed of light in a vacuum (2.998 x 10 8 m/s) This equation shows that energy has a mass equivalent Example on page 47 Mass & Energy
Page 47 Questions 7-10 Do them on your iPad and send them to my address Practice Questions