1. Types of Chemical Reactions
Chemical reactions are grouped into categories. Within each category, the reactions follow the same pattern
Synthesis Reaction
Decomposition Reaction
Single Displacement Reaction
Double Displacement Reaction
Combustion Reaction

2. Synthesis Reactions
These reactions involve two or more substances combine to form a larger or more complex substance.
General pattern:  A + B  AB
element + element  compound
compound + compound  one larger compound
Example: hydrogen + oxygen  water
copper + oxygen  copper oxide
calcium oxide + water  calcium hydroxide

3. Decomposition Reactions
These are reactions in which a large or more complex molecule is broken down into two or more simpler substances.
General pattern: AB  A + B
Example: sodium chloride  sodium + chlorine
water  hydrogen + oxygen
potassium chlorate  potassium chloride + oxygen

4. Single Displacement Reactions
A reaction in which one element takes the place of another element in a compound, producing a new compound and a new element.
General pattern: A + BC  AC + B (if A is a metal)
A + BC  BA + C (if A is a non-metal)
A represents an element; BC represents a compound
element + compound  compound + element
Example:
 calcium + hydrogen hydroxide  hydrogen + calcium hydroxide
chlorine + sodium bromide  sodium chloride + bromine

5. Double Displacement Reactions
A reaction that occurs when elements in different compounds displace each other or exchange places, producing two new compounds.
General pattern: AB + CD  AD + CB
The symbols A, B, C, and D represent atoms, single ions, or polyatomic ions.
compound + compound  compound + compound
Example:
potassium hydroxide + hydrogen chloride  potassium chloride + hydrogen hydroxide
lead (II) nitrate + hydrogen chloride  lead (II) chloride + hydrogen nitrate

6. Sometimes, in a reaction of aqueous reactants, one of the products is insoluble. This product, called a precipitate, appears as a solid in the solution.

7. Combustion
The very rapid reaction of a substance with oxygen to produce compounds called oxides (often called burning)
word equation to represent combustion:
fuel + oxygen  oxides + energy
The energy produced is mainly in the form of heat and light and the fuel can be a variety of elements and compounds.

8. Complete Combustion of Hydrocarbons
occurs when the supply of oxygen is plentiful
the only products of complete combustion are carbon dioxide and water
the word equation for the complete combustion of a hydrocarbon is:
hydrocarbon + oxygen  carbon dioxide + water + energy
most important fuels we burn are hydrocarbons (Ex: gasoline, natural gas, kerosene)

9. Incomplete Combustion of Hydrocarbons
occurs when oxygen supply is limited
products of incomplete combustion are carbon monoxide gas, carbon (soot), carbon dioxide and water
carbon monoxide is an odourless, colourless gas that is highly toxic
sources of carbon monoxide include: poorly ventilated furnace or a closed garage with a running vehicle in it
soot is common in older vehicles with poorly maintained engines

10. Incomplete Combustion of Hydrocarbons
the word equation for incomplete combustion of a hydrocarbon is:
hydrocarbon + oxygen  carbon dioxide + water + carbon monoxide + carbon + energy
Some metals react with oxygen in combustion reactions, producing oxides of the metal (e.g., magnesium oxide, MgO)
General word equation: element + oxygen  oxide + energy