Chemical Reactions Glencoe Chapter 23

I. Chemical reactions change substances Substances undergo chemical changes to become new substances A. Signs of a chemical reaction 1. Production of gas or smoke 2. Change in color (not like painting a fence) 3. Change in temperature without heating or cooling 4. Production of a solid from two liquids

I. Chemical reactions change substances B. Chemical reactions rearrange atoms to form new substances Chemical Reaction - the process in which one or more substances are changed into new substances 1. Reactants  beginning materials / substances that undergo a chemical change 2. Products  ending materials / substances that are formed as a result of a chemical change

II. Energy and Reactions A. Energy added to a compound to break chemical bonds B. Energy released from a compound to form chemical bonds C. Exothermic reactions – reactions that release energy (usually in the form of heat and/or light) D. Endothermic reactions – reactions that absorb energy (usually get colder during the reaction)