This document provides definitions and examples of key chemistry concepts including: - Cations are positive ions and anions are negative ions. Examples include sodium (Na+) and chloride (Cl-). - For a reaction to occur, particles must collide with sufficient energy, called the activation energy. Reaction rates can be increased by greater surface area, concentration, temperature, or using a catalyst. - Chemical changes form new substances, while physical changes do not. Chemical changes cannot be easily reversed. Combustion and oxidation reactions involve reactions with oxygen. Reduction is the opposite of oxidation.

1. Solids Liquids and Gases
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2. Cations and Anions
A positive ion is called a cation.
eg.__________
A negative ion is called an anion.
eg ____________

3. In order to react particles need to collide.
A certain amount of energy is necessary for a
reaction to take place. This is called the
activation energy.
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4. Reaction Rates
Four things can speed up the rate of a reaction:
Increasing the surface area.
_____________________________________
Increasing the concentration.
_____________________________________
Increasing the temperature.
______________________________________
Using a catalyst
This lowers the activation energy required.

5. Chemical and Physical Change
In a chemical change, new substances are
formed.
Evidence of a chemical change includes light and
heat being given off, and something changing
colour (ie becoming a new substance).
A chemical change cannot easily be changed
back.
In a physical change, no new substances are
made, so they can be more easily changed
back.

6. Oxidation
An oxidation reaction occurs when something
reacts with oxygen.
Eg: iron (III) + oxygen --> iron (III) oxide.

7. Combustion
A combustion reaction is when something burns.
eg. Hydrogen + Oxygen --> ___________
The substance which burns reacts with oxygen in
the air (O2).
Most combustion reactions are exothermic (give
off heat). Many also give off light.
All combustion reactions are oxidation reactions
(but not vice versa).

8. Reduction
A reduction reaction occurs when something loses
oxygen. It is the opposite of an oxidation
reaction.
eg.iron oxide + carbon --> iron + carbon dioxide.

9. Please Bring a Ruler to the Exam!