π Exam Structure
| Paper | Focus | Marks | Time |
|---|
| Paper 1 | Physics | 150 | 2 hours |
| Paper 2 | Chemistry | 150 | 2 hours |
β οΈ Paper 2 Chemistry topics: Matter & Materials, Chemical Change, Chemical Systems
π Topic 1: Matter & Materials
Classification of Matter
Matter
βββ Pure Substances
β βββ Elements (e.g., Na, Fe, Oβ)
β βββ Compounds (e.g., NaCl, HβO)
βββ Mixtures
βββ Homogeneous (same throughout, e.g., salt water)
βββ Heterogeneous (different parts, e.g., sand + water)
Separation Techniques
| Method | What it separates | Example |
|---|
| Filtration | Solid from liquid | Sand from water |
| Evaporation | Dissolved solid from liquid | Salt from salt water |
| Distillation | Liquids with different boiling points | Water from ink |
| Chromatography | Different coloured inks | Pen ink colours |
| Magnetic separation | Magnetic from non-magnetic | Iron filings from sand |
Atomic Structure
- Proton: positive charge, in nucleus, mass β 1
- Neutron: no charge, in nucleus, mass β 1
- Electron: negative charge, orbits nucleus, mass β 0
Atomic number (Z) = protons | Mass number (A) = protons + neutrons | Neutrons = A β Z
Isotopes: Same element (same protons), different neutrons. Example: Carbon-12 and Carbon-14
Electron Configuration
- 1st shell: max 2 electrons
- 2nd shell: max 8 electrons
- 3rd shell: max 8 electrons (Grade 10)
π‘ Example: Sodium (Na) = 2, 8, 1 β it has 11 electrons total
The Periodic Table
- Groups (vertical): Same group = similar properties
- Periods (horizontal): Same row = same number of electron shells
- Group 1: Alkali metals (very reactive)
- Group 17: Halogens (very reactive non-metals)
- Group 18: Noble gases (unreactive / inert)
Chemical Bonding
| Type | Between | What happens | Properties |
|---|
| Ionic | Metal + Non-metal | Electron transfer β ions | High melting point, conducts when dissolved |
| Covalent | Non-metal + Non-metal | Electron sharing β molecules | Low melting point, doesn't conduct |
| Metallic | Metal + Metal | "Sea" of delocalised electrons | Conducts heat & electricity, malleable |
π‘ Easy way to remember: Ionic = transfer ("I" for "give away"), Covalent = share ("Co" for "together")
Naming Compounds (Nomenclature)
Suffixes:
-ide β simple ion (chloride Clβ», oxide OΒ²β», sulphide SΒ²β»)-ite β less oxygen (sulphite SOβΒ²β»)-ate β more oxygen (sulphate SOβΒ²β»)
Prefixes: 1=mono-, 2=di-, 3=tri-, 4=tetra-, 5=penta-, 6=hexa-
Rule of Neutrality: Total positive charge + total negative charge = 0
Examples: NaCl β Sodium chloride | COβ β Carbon dioxide | MgSOβ β Magnesium sulphate
π Topic 2: Chemical Change
Law of Conservation of Matter
βοΈ Matter cannot be created or destroyed. Atoms in reactants = atoms in products. Mass of reactants = mass of products.
Note: The number of MOLECULES is NOT necessarily conserved β only atoms!
Balancing Chemical Equations
- Write the word equation
- Write the unbalanced formula equation
- Count atoms on each side
- Add coefficients to balance
- Check all atoms balance
Word: Methane + Oxygen β Carbon dioxide + Water
Formula: CHβ + Oβ β COβ + HβO
Balanced: CHβ + 2Oβ β COβ + 2HβO
Check: 1C, 4H, 4O = 1C, 4H, 4O β
Types of Reactions
| Type | Pattern | Example |
|---|
| Synthesis | A + B β AB | 2Mg + Oβ β 2MgO |
| Decomposition | AB β A + B | 2HβOβ β 2HβO + Oβ |
| Single Replacement | A + BC β AC + B | Zn + CuSOβ β ZnSOβ + Cu |
| Double Replacement | AB + CD β AD + CB | AgNOβ + NaCl β AgCl + NaNOβ |
| Neutralisation | Acid + Base β Salt + Water | HCl + NaOH β NaCl + HβO |
| Combustion | Substance + Oβ β COβ + HβO | CHβ + 2Oβ β COβ + 2HβO |
Acids and Bases
| Acids | Bases |
|---|
| pH | < 7 | > 7 |
| Taste | Sour | Bitter |
| Feel | β | Slippery |
| Litmus | Blue β Red | Red β Blue |
Common acids: HCl, HβSOβ, HNOβ, acetic acid (vinegar)
Common bases: NaOH, KOH, Ca(OH)β, NHβ (ammonia)
π¬ Ion Testing (MUST MEMORISE!)
| Ion | Reagent | Observation |
|---|
| Chlorides (Clβ») | AgNOβ + HNOβ | White precipitate (AgCl) |
| Sulphates (SOβΒ²β») | Ba(NOβ)β + HNOβ | White precipitate (BaSOβ) β does NOT dissolve in acid |
| Carbonates (COβΒ²β») | Ba(NOβ)β + acid | Precipitate forms, then dissolves, releasing COβ gas |
| Iron (FeΒ³βΊ) | NaOH | Brown precipitate |
| Copper (CuΒ²βΊ) | NaOH | Blue precipitate |
Stoichiometry (Mole Calculations)
n = m / M | C = n / V | n = C Γ V
- Mole: 6.022 Γ 10Β²Β³ particles (Avogadro's number)
- Molar mass: Mass of 1 mole (g/mol) β use periodic table
- Concentration: moles per volume (mol/dmΒ³)
π‘ Example: How many moles in 4g of NaOH?
M(NaOH) = 23 + 16 + 1 = 40 g/mol
n = m/M = 4/40 = 0.1 mol
Energy in Reactions
| Type | Energy | Feels like | Examples |
|---|
| Exothermic | Released (ΞH < 0) | Warm/hot | Combustion, neutralisation |
| Endothermic | Absorbed (ΞH > 0) | Cold | Photosynthesis, thermal decomposition |
π Topic 3: Chemical Systems
Water Cycle & Purification
Natural cycle: evaporation β condensation β precipitation
Purification steps: screening β coagulation β sedimentation β filtration β disinfection
π‘ Test for water: Anhydrous CuSOβ (white) turns blue when water is present
The Nitrogen Cycle
- Nitrogen fixation: Nβ β NHβ/NOββ» (by bacteria or lightning)
- Nitrification: NHβ β NOββ» β NOββ»
- Denitrification: NOββ» β Nβ (back to atmosphere)
- Nitrogen is essential for plant growth β fertilisers
Greenhouse Effect & Global Warming
- Greenhouse gases: COβ, CHβ, water vapour, NβO
- Natural greenhouse effect keeps Earth warm (good!)
- Enhanced greenhouse effect β global warming (bad!)
- Consequences: rising sea levels, extreme weather, ecosystem changes
π¬ Practical Work
Common practical exam questions:
- Identifying ions using precipitation reactions
- Testing for gases:
| Gas | Test | Result |
|---|
| Hβ | Lighted splint | "Pop" sound |
| Oβ | Glowing splint | Relights |
| COβ | Limewater | Turns milky/murky |
- Measuring pH using indicators or pH meter
- Observing and recording reactions
- Drawing particle diagrams for elements, compounds, mixtures
π Exam Tips
1 Memorise the ion testing table β it comes up every year
2 Practice balancing equations β 10 per study session
3 Know periodic table trends β atomic radius, electronegativity
4 Understand ionic vs covalent vs metallic bonding β draw diagrams
5 Practice mole calculations β n = m/M and C = n/V
6 Read questions carefully β "write the formula" vs "name the compound"
7 Show ALL working β you get method marks
8 Units matter β always include g, mol, dmΒ³, etc.
π Past papers are gold! Do as many as possible under timed conditions.
π Free Resources
Past Exam Papers (with memos):
YouTube: Search "Grade 10 Physical Sciences Chemistry CAPS" for video lessons