Chapter 6 

Chemical Reactions

• A chemical reaction produces a signal that it has occurred. These signals include

  • Color change

  • Solid formation

  • Bubble formation

  • Heat

  • Flame

• The physical states of reactants and products in a reaction are indicated by the following symbols: (s), (l), (g), or (aq).

• Chemical reactions involve a rearrangement of the ways atoms are grouped together.

• A chemical equation represents a chemical reaction.

  • Reactants are shown to the left of an arrow.

  • Products are shown to the right of the arrow.

• In a chemical reaction, atoms are neither created nor destroyed. A balanced chemical equation must have the same number of each type of atom on the reactant and product sides.

• A balanced chemical equation uses numbers (coefficients) in front of the reactant and product formulas to show the relative numbers of each.

• A chemical reaction is balanced by using a systematic approach.

  • Write the formulas of the reactants and products to give the unbalanced chemical equation.

  • Balance by trial and error, starting with the most complicated molecule(s).

  • Check to be sure the equation is balanced (same numbers of all types of atoms on the reactant and product sides).

KEYs