Chemical Reactions Glencoe Chapter 23

I. Chemical reactions change substances

Substances undergo chemical changes to become new substances

A. Signs of a chemical reaction1. Production of gas or smoke2. Change in color (not like painting a fence)3. Change in temperature without heating or cooling4. 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)