⚡ Quick Revision: Water at a Glance
- Water is a compound made of hydrogen and oxygen.
- Water is called a universal solvent because it dissolves many substances.
- All living things need water to survive.
Makeup: 2 Hydrogen atoms + 1 Oxygen atom.
Hydrogen + Oxygen → Water
Observation: Hydrogen and oxygen combine chemically to form water.
Pure water contains only H₂O particles vs Drinking water may contain useful dissolved minerals.
Do not write that water is an element. Water is a compound because it is made of hydrogen and oxygen.
H-H-O = H₂O
Two H atoms and one O atom make one water molecule.
| Use of Water | Where Used | Quick Recall |
|---|---|---|
| Drinking | Humans and animals | Needed for life 🔥 |
| Cooking | Homes | Helps prepare food |
| Irrigation | Farms | Needed by crops |
| Cleaning | Homes and schools | Maintains hygiene |
- Water is essential for life.
- Water is a compound.
- The formula of water is H₂O.
- Water contains hydrogen and oxygen.
- Potable water is safe drinking water.
⚡ Quick Revision: Sources and States of Water
- Rain is the main natural source of water.
- Water exists in three states: solid, liquid and gas.
- Ice is solid water, water is liquid water and water vapour is gaseous water.
Makeup: Same formula in ice, liquid water and water vapour.
Ice + Heat → Water
Observation: Solid water changes into liquid water.
Water - Heat → Ice
Observation: Liquid water changes into solid water.
Water + Heat → Water Vapour
Observation: Liquid water changes into gas.
Water Vapour - Heat → Water Droplets
Observation: Gaseous water changes into liquid water.
Evaporation changes water into water vapour vs Condensation changes water vapour into water droplets.
Do not write that ice has a different formula from water. Ice, liquid water and water vapour are all H₂O.
I-W-V
Ice is solid, Water is liquid, Vapour is gas.
| Form / Source | Type | Quick Recall |
|---|---|---|
| Ice | Solid state | Solid H₂O 🔥 |
| Liquid Water | Liquid state | Used for drinking and washing |
| Water Vapour | Gaseous state | Invisible gas form of water |
| Rain | Natural source | Main source of freshwater |
- Rain is the main natural source of water.
- Water is found as ice, liquid water and water vapour.
- Melting changes ice into water.
- Evaporation changes water into water vapour.
- Condensation changes water vapour into water droplets.
⚡ Quick Revision: Water Cycle Recall
- The Sun is the main source of heat for the water cycle.
- Water cycle helps maintain water on Earth.
- Main steps are evaporation, condensation, precipitation and collection.
Makeup: Water remains H₂O during the water cycle.
Water Bodies → Evaporation → Condensation → Clouds → Rain → Collection
Observation: Water keeps moving between Earth and atmosphere.
Clouds are formed by condensation of water vapour vs Rain is precipitation falling from clouds.
Do not write that evaporation forms rain directly. Evaporation first forms water vapour, then condensation forms clouds.
E-C-P-C
Evaporation, Condensation, Precipitation, Collection complete the water cycle.
| Step | Meaning | Quick Recall |
|---|---|---|
| Evaporation | Water changes into vapour | Caused by Sun's heat 🔥 |
| Condensation | Vapour changes into droplets | Forms clouds |
| Precipitation | Water falls from clouds | Rain, snow or hail |
| Collection | Water gathers on Earth | Rivers, lakes, oceans |
- Water cycle is the continuous movement of water.
- Sun provides heat for evaporation.
- Condensation forms clouds.
- Precipitation brings water back to Earth.
- Collection stores water in rivers, lakes and oceans.
⚡ Quick Revision: Water Pollution and Conservation
- Polluted water can cause diseases.
- Sewage, factory waste and garbage pollute water.
- Water must be conserved because freshwater is limited.
Makeup: Clean water should be free from harmful pollutants.
Dirty Water → Filtration → Boiling → Safer Water
Observation: Filtration removes insoluble impurities and boiling kills many germs.
Careful Use + Repair Leaks + Reuse Water → Water Conservation
Observation: Small daily actions help save freshwater.
Clean water may look clear vs Safe drinking water is free from harmful germs and pollutants.
Do not write that clear water is always safe to drink. It may contain invisible germs or dissolved harmful substances.
S-F-G
Sewage, Factory waste and Garbage are common water pollutants.
| Pollutant | Source | Effect |
|---|---|---|
| Sewage | Homes and drains | Spreads diseases 🔥 |
| Factory Waste | Industries | Harms aquatic life |
| Garbage | Human activities | Makes water dirty and unsafe |
| Oil | Oil spills and vehicles | Blocks oxygen for aquatic animals |
- Water pollution means harmful substances in water.
- Sewage and factory waste pollute water.
- Polluted water can cause diseases.
- Clear water may not always be safe.
- Water conservation means saving water carefully.
⚡ Quick Revision: Final Exam Recall Sheet
- 🔥 Water is a compound with the formula H₂O.
- 🔥 Water exists in three states: ice, liquid water and water vapour.
- 🔥 The water cycle includes evaporation, condensation, precipitation and collection.
Makeup: 2 Hydrogen atoms + 1 Oxygen atom.
Ice → Water → Water Vapour
Observation: Water changes state but remains H₂O.
Evaporation → Condensation → Precipitation → Collection
Observation: Water keeps moving between Earth and atmosphere.
Dirty Water → Filtration → Boiling → Safer Water
Observation: Filtration removes insoluble impurities and boiling kills many germs.
Evaporation forms water vapour vs Condensation forms water droplets.
Do not write that clear water is always safe to drink. It may contain invisible germs or harmful dissolved substances.
H₂O + E-C-P-C + S-F-G
H₂O is water, E-C-P-C is water cycle, and S-F-G are common water pollutants.
| Concept | Quick Recall | Exam Trap |
|---|---|---|
| Water | Compound, H₂O | Not an element 🔥 |
| Three States | Ice, water, water vapour | All are H₂O |
| Water Cycle | Movement of water | Evaporation does not form rain directly |
| Polluted Water | Water with harmful substances | Clear water may still be unsafe |
| Process | Change | Quick Example |
|---|---|---|
| Melting | Ice → Water | Ice cube melts |
| Freezing | Water → Ice | Water kept in freezer |
| Evaporation | Water → Water vapour | Wet clothes dry 🔥 |
| Condensation | Water vapour → Water droplets | Droplets on cold glass |
Water → H₂O → Three States → Water Cycle → Pollution Control → Conservation
- Water is a compound with formula H₂O.
- Ice, liquid water and water vapour are three states of water.
- Sun's heat causes evaporation in the water cycle.
- Polluted water can spread diseases.
- Water conservation means using water carefully.