Chemical Bonding

A.  Chemical Changes in Matter

1.  Reactants are the substances about to react

2.  Products are the substances produced by a reaction

B.  Conservation of Mass

1.  Discovered by Antoine Lavoisier

2.  In a chemical reaction matter is not created or destroyed but is conserved

3.  The total mass of the reactants must equal the total mass of the products

C.  Chemical Equations

1.  They must be balanced (the total number of atoms of each element on each side must be equal)

2.  Once subscripts have been assigned, they may not be changed

3.  The only thing that can be changed are the coefficients in front of the elements or compounds

D.  Types of Chemical Reactions

1.  Synthesis (Composition) - two or more substances combine to form another substance

2.  Decomposition - one substance breaks down into two or more simpler substances

3.  Single displacement - one element replaces another in a compound

4.  Double displacement

a.  Elements in two different compounds replace one another

b.  Occurs when a precipitate, water, or a gas forms when two ionic compounds in solution are combined

E.  Energy Changes in Chemical Reactions

1.  Endothermic reactions

a.  Energy must be provided in order for the reaction to take place

b.  The products of this reaction are cooler (they absorb heat)

2.  Exothermic reactions

a.  Energy is given off by the reaction

b.  The products may be hotter

3.  Catalysts are substances that speed up reactions without themselves being changed

4.  Inhibitors are the same as catalysts, but instead they slow down reactions