Trilogy – Chemistry – CHAPTER 5 – Energy changes What is an element? Colliding particles Chemicals are made up from __________that have their own ______________. When particles meet they ______________. Only those collisions that have enough _____________ can react. The energy needed to start a reaction is called the ___________ __________. ______________ lower the activation energy by providing a different __________ for the reaction. What is the definition of an exothermic reaction? What happens to the temperature in an exothermic reaction? Give 3 examples of exothermic reactions. Give an everyday use of exothermic reactions. What is the definition of an endothermic reaction? What happens to the temperature in an endothermic reaction? Give 3 examples of endothermic reactions Give an everyday use of an endothermic reaction. What is a compound? What is a molecule? What is a chemical reaction? Draw a reaction profile for an exothermic reaction (label reactants, products, activation energy and energy given out during the reaction): Draw a reaction profile for an endothermic reaction (label reactants, products, activation energy and energy taken in during the reaction): Bond energies Energy must be _______ to break bonds. Energy is ___________ when bonds area formed. The amount of energy needed for bond breaking must be compared with the amount released when new bonds are formed. If less energy is needed to break bonds than released on making bonds, the reaction is ____________. If more energy is needed to break bonds than released on making bonds, the reaction is ____________. KEY WORDS: Exothermic Endothermic Bond making Bond breaking Reaction profile Reactants Products ASSESSMENT: