1. YEAR 9 CHEMISTRY REVISION
GOOD LUCK!

2. Structure of Atom In the cloud : Electrons (negative)
In the Nucleus: Protons (positive)
Neutrons (neutral)

3. Subatomic Particles In an atom: The Protons = the Electrons
If 20 protons are present in an atom then 20 electrons are there to balance the overall charge of the atom—atoms are neutral
The neutrons have no charge; therefore they do not have to equal the number of protons or electrons

4. Atomic Number
Atomic number: this number indicates the number of protons (and electrons) in an atom
Ex: Hydrogen’s atomic number is 1
So hydrogen has 1 proton and 1 electron
Ex: Carbon’s atomic number is 6
So carbon has 6 protons and 6 electrons

5. Physical Change A changes in certain properties such as: Shape
State (Solid, liquid, gas)
NO NEW SUBSTANCES ARE CREATED
Examples: dissolving sugar, melting ice

6. Chemical Change Chemical changes produce new substances Heat Gas
Bubbles
Light
Examples: making toast, burning wood

7. Metals React with acids
They are more of them than non-metals and are on the left side
Conducts electricity
Glows quickly and cools quickly
Generally sink
Shiny and strong
They a sonorous (make a ringing sound)
Solids at room temperature
They Malleable and Ductile

8. Non Metals On the right side of the periodic table Generally float
Gases at room temperature
Don't conduct electricity and so they are insulators
Really slow to heat up or cool down
Very brittle- which means they break easily
Very dull looking

9. Acids pH 1-6 React with Metals turn blue litmus paper red corrosive
sour taste
red/pink in universal indicator
Common examples: Milk, HCL, Citric Acid

10. Bases pH 8-9 Turns red litmus paper blue bitter
blue/ purple in universal indicator
common examples: soap, detergent, cleaning products

11. Neutrals pH 7 No reaction to litmus paper Green in universal indicator
ACID + BASE = Neutralisation
Common Examples: Water

12. Acid and Metal Reactions
Acid + Metal -> Salt + Hydrogen Gas Acid + Metal Carbonate -> Salt + water + Carbon Dioxide Acid + Base -> Salt + Water