chemical reactions

1. Chemical Reactions
• Single displacement reaction – reaction in which one element take
the place of another element in a compound
• Synthesis reaction – reaction in which tow or more substance
combine to form a new substance
• Decomposition reaction – reaction in which a single compound
breaks down to form two or more simpler substances.
• Double displacement reaction – reaction in which a gas, precipitate,
or molecular compound forms from the exchange of ions between
two compounds

2. Laws and Energy
• Law of conservation of energy – the law that states that energy
cannot be created or destroyed but can be changes from one form to
another
• Law of conservation of mass – law that states that mass cannot be
created or destroyed in ordinary chemical or physical changes
• Exothermic reactions – energy is released, usually in the form of heat
• Endothermic reactions – energy is added, usually in the form of heat
• Activation energy – minimum amount of energy needed to start a
chemical reaction

3. • Catalyst – substance that changes the rate of a reaction without being
used up or changed
• Inhibitor – substance that can slow down or stop a chemical reaction

4. Parts of a Chemical Equation
• Chemical equations consist of reactants (what you start with) and
products (what you end up with)
• Because of the laws of mass and energy, what you start with
(reactants) must appear in what you end up with (products)

5. Steps to balance equations:
1. Separate the equation
2. List all elements on each side of the equation
3. Count the total number of atoms for each element
4. Find the first element that does not balance
5. ADD a coefficient to the front of the chemical formula for that
element and recalculate the number of atoms in the equation
6. Repeat the process until the left side is equal to the right side of the
equation