1. (Things you should already know and remember)
REVIEW OF SECONDARY 4
(Things you should already know and remember)

2. Why is the Periodic Table important to me?
The periodic table is the most useful tool to a chemist.
You get to use it on every test.
It organizes lots of information about all the known elements. 2

3. The Current Periodic Table
The horizontal rows are called periods.
The vertical columns are called groups (families).
Group 1: Alkali Metals
Group 2: Earth Alkali Metals
Group7 : Halogens
Group 8: Inert (Noble) Gases
Transition Metals: in the middle 3

4. PHYSICAL CHANGES Reversible
Change in state: such as boiling, melting, evaportaion,…
Basic identity of substance remains the same
Reversible

5. CHEMICAL CHANGES Irreversible Basic identity of substance changes
Signs of chemical change:
Bubbles
Precipitate forms
Color change
Heat or light is given off
Electricity produced

6. DID YOU KNOW?
A chemical reaction inside fireflies enables them to light up. It is called bioluminescence.
Fireflies shine for a variety of reasons.
It has been shown that females are more attracted to males who emit faster and more intensive flashes of light.

7. ELEMENTS
Elements are made up of only one kind of atom, and they cannot be broken down.
They are pure substances.

8. COMPOUNDS
They are pure substances that can be broken down into simpler substances.
They are made up of 2 or more elements that are chemically combined.

9. MIXTURES
They are impure substances that are combined physically and can be separated physically.
There are 2 types of mixtures:
Homogeneous Heterogeneous
Salt and Water Sand and Water

10. CHEMICAL EQUATIONS Oxygen + Hydrogen  Water (word equation)
O2 (g) + H2 (g)  H2O (l ) (chemical equation)
REACTANTS PRODUCTS
(g) stands for gas, (l) stands for liquid, (s) stands for solid, (aq) stands for aqueous

11. TYPES OF CHEMICAL REACTIONS
Synthesis: Combination Reaction
Copper + Oxygen  Copper Oxide
 Cu O2  CuO
Decomposition:
Water  Hydrogen + Oxygen
 H2O  H2 + O2

12. Synthesis General: A + B  AB Example C + O2 CO2  + O O O O O O O O

13. Decomposition
Example: NaCl  Cl Na Cl + Na
General: AB  A + B

14. Single displacement General: AB + C  AC + B Example: Zn + CuCl2  + +

15. Double displacement General: AB + CD  AD + CB Example: MgO + CaS  +

16. More examples Single Displacement: CuO + C  Cu + CO2
Double Displacement:
BaCl K2CO > BaCO KCl

17. Combustion Reactions
Oxygen reacts with another substance producing carbon dioxide and water and releases heat.
CH4 + 2O2 --> CO H2O + heat

18. Balancing Chemical Equations
Balance the following Haber Process:
N2 + H2  NH3
You should have got N2 + 3H2  2NH3
This chemical reaction is named after Fritz Haber. A German chemist who found a way to combine nitrogen and hydrogen to ammonia which can be pumped directly into the soil as a fertilizer.