chemical reactions glencoe chapter 23. i. chemical reactions change substances substances undergo...

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)