1. Chemical Reactions

2.  In chemical reactions, one or more substances change into different substances. example: combustion

3. Word Equations and Chemical Equations  Chemists use equations to describe chemical reactions.  Word equations show the names of the materials in the chemical reaction.  Chemical equations show the chemical formulas of the materials in the chemical reaction. (starting materials)(yields)(ending materials) REACTANT PRODUCTS

4.  Word equation: sodium + chlorine sodium chloride Chemical equation: Na + Cl NaCl

5. Common State Symbols in Chemical Equations State SymbolMeaningExample Solid Liquid Gaseous Aqueous (dissolved in water) (s) (l)(l) (g)(g) ( aq ) (sodium chloride) NaCl (s) (bromine) Br 2(l) (hydrogen) H 2 ( g) (aqueous sodium chloride solution) NaCl (aq)

6.  Word Equation: sodium chlorinechemical reaction sodium chloride sodium (s) + chlorine (g) sodium chloride (s) Chemical Equation: Na (s) + Cl 2(g) NaCl (s) Let’s go back to the example we used

7. zinc (s) + copper(II) sulphate (aq) Word Equation: Chemical Equation: Zn (s) + CuSO 4(aq) zinc sulphate (aq) + copper (s) + energy ZnSO 4(aq) + Cu (s) + energy zinc copper(II) sulphate zinc sulphate copper