Year 7 SEEP Science Revision Guide Notes

Discovering Science

The Science Laboratory

  • Scientific Diagram vs. Artist’s Drawing: A scientific diagram is simplified, accurate, and labelled to show structure or processes, avoiding extra detail. An artist’s drawing is more detailed and expressive, aiming for realism or creativity.
  • Apparatus: A set of tools used together for a specific scientific experiment. Example: Bunsen burner, tripod, and beaker.
  • Equipment: General items used in a lab to perform tasks or experiments. Example: Thermometers, microscopes, and measuring cylinders.

Measuring and Reading Scales

  • Volume: Use measuring cylinders or beakers on a flat surface. Read the liquid level at eye level at the bottom of the meniscus. Record in millilitres (mLmL) or litres (LL).
  • Parallax Error: Occurs when reading a scale from the wrong angle. Avoid by reading scales straight on at eye level.
  • Temperature: Use a thermometer properly in the substance, not touching the container. Wait for it to stabilise, then read at eye level. Record in degrees Celsius (°C°C).

Safety Precautions in the Lab

  • Always wear safety goggles.
  • Tie back long hair and avoid loose clothing.
  • Never eat or drink in the lab.
  • Follow teacher’s instructions and read labels.
  • Report spills or breaks immediately.
  • Know the location of safety equipment.
  • Wash hands and clean workspace after experiments.

Using a Bunsen Burner

  • A Bunsen burner heats substances by mixing gas with air. Air amount is adjusted via the air hole.
  • Lighting: Close the air hole for a yellow safety flame. Connect to the gas tap using a rubber hose. Strike a match, hold it above the barrel, and slowly turn on the gas tap. Open the air hole for a blue, hotter flame.
  • Safety: Wear safety goggles, tie back long hair, never leave unattended, use the yellow flame when not actively heating. Turn off the gas tap and let the burner cool before handling.

Scientific Inquiry

Fair Test

  • A controlled experiment where only one variable is changed at a time for accurate and reliable results.

Variables

  • Independent Variable: Changed on purpose.
  • Dependent Variable: Measured or observed.
  • Controlled Variables: Kept the same to ensure fairness.

Scientific Report

  • Communicates experiment findings clearly.
  • Steps:
    1. Title
    2. Aim
    3. Hypothesis
    4. Materials
    5. Method
    6. Results
    7. Discussion
    8. Conclusion

Hypothesis

  • A prediction in “If… then…” format.
  • Example: If the temperature of water increases, then sugar will dissolve faster.

Aim

  • Explains what you are trying to find out.
  • Example: To investigate how temperature affects the rate at which sugar dissolves in water.

Analysing Data

Graphs

  • Pie Chart: Shows data as parts of a whole, useful for percentages. Analyse by comparing slice sizes.
  • Column Graph (Bar Graph): Compares categories using column height. Best for discrete data. Analyse by looking for the tallest and shortest bars.
  • Histogram: Similar to a bar graph but for continuous data grouped into ranges. Bars touch. Analyse for highest/lowest frequency.
  • Line Graph: Shows data changes over time. Spot trends and patterns.

Observation and Conclusion

  • Observation: A factual statement based on direct sensory input or measurement. Example: “The plant grew 5 cm in one week.”
  • Conclusion: Explains what observations mean in relation to the experiment’s aim or hypothesis.
  • Example: “The plant grew taller when given more sunlight, so sunlight helps plant growth.” Base conclusions on data collected.

Separating Mixtures

Pure Substances and Mixtures

  • Pure Substances: Made of one type of particle.
    • Elements: One kind of atom (e.g., oxygen, gold).
    • Compounds: Two or more different atoms chemically combined in fixed ratios (e.g., water, H2OH₂O).
  • Mixtures: Two or more substances not chemically bonded.
    • Homogeneous: Same composition throughout (e.g., salt dissolved in water).
    • Heterogeneous: Visibly different parts or layers (e.g., salad).

Types of Mixtures

  • Suspension: Solid particles dispersed in a liquid, settling over time (e.g., muddy water).
  • Emulsion: Two liquids that don’t mix dispersed with an emulsifier (e.g., milk, mayonnaise).
  • Colloid: Tiny particles dispersed evenly, don’t settle (e.g., fog, whipped cream).
  • Solution: Homogeneous mixture where a solute dissolves completely in a solvent (e.g., sugar in water).

Concentrations of Solutions

  • Concentrated: Large amount of solute in a small amount of solvent.
  • Saturated: Maximum amount of solute dissolved at a given temperature. Extra solute remains undissolved.
  • Dilute: Small amount of solute in a large amount of solvent.

Separating Solids from Mixtures

  • Suspension: A mixture in which solid particles are dispersed throughout a liquid but are large enough to eventually settle out over time.
  • Sediments: Solid particles that settle at the bottom of a suspension.
  • Soluble: A substance that can dissolve in a solvent (e.g., sugar in water).
  • Insoluble: A substance that cannot dissolve in a solvent (e.g., sand in water).
  • Solute: The substance that is dissolved in a solvent (e.g., salt in saltwater).
  • Solvent: The substance that dissolves the solute (e.g., water in saltwater).

Separation Techniques

  • Decanting: Pouring off a liquid from settled solids (sediments).
  • Sieving: Separating solids of different sizes using a mesh.

Other Separating Techniques

  • Separating Funnel: Separates immiscible liquids (e.g., oil and water) based on density.
  • Centrifuging: Separates substances of different densities by spinning at high speed.
  • Magnetic Separation: Separates magnetic materials using a magnet.

Separating Solutions

  • Distillation: Separates mixtures based on boiling points.
  • Evaporation: Separating a dissolved solid from a liquid by letting the liquid evaporate.
  • Crystallization: Obtaining pure solid crystals from a solution by evaporation and slow cooling.

Removing Contamination from Water

  • Desalination: Removing salt from seawater to produce fresh water.
  • Osmosis: Movement of water molecules through a membrane from low to high solute concentration.
  • Flocculation: Adding a chemical (flocculant) to clump fine particles together for easier settling.

Rocks and Minerals

Definitions

  • Rocks: Naturally occurring solid mixtures of one or more minerals.
  • Minerals: Naturally occurring inorganic substances with a fixed chemical composition and crystal structure.

Mineral Identification

  • Lustre: How light reflects from a mineral’s surface (metallic, pearly, dull, earthy).
  • Streak: The colour of the mineral in powdered form.
  • Hardness: Measured using the Mohs scale (1-10).
  • Cleavage: How a mineral breaks along flat surfaces.
  • Ore: A mineral with a large amount of useful metal in it.

Igneous Rocks

  • Magma: Molten rock beneath the Earth’s surface.
  • Lava: Molten rock erupted onto the Earth’s surface.
  • Formation: Igneous rocks are formed when magma or lava cools and solidifies.
  • Intrusive Rocks: Cool slowly underground with large crystals (e.g., granite).
  • Extrusive Rocks: Cool quickly on the surface with small or no visible crystals (e.g., basalt).

Sedimentary Rocks

  • Formation: Sedimentary rocks are formed from the accumulation and compaction of sediments over time.
  • Sediments Examples: Sand, silt, clay, and fragments of shells or plants.
  • Types:
    • Clastic: Formed from fragments of other rocks (e.g., sandstone).
    • Chemical: Formed from minerals precipitating from water (e.g., limestone).
    • Organic: Formed from accumulated plant or animal remains (e.g., coal).
  • Weathering: Breakdown of rocks into smaller pieces.
  • Erosion: Movement of weathered particles.
  • Lithification: Sediments compacted and cemented to form solid rock.

Metamorphic Rocks

  • Formation: Metamorphic rocks form when existing rocks are changed by intense heat and pressure.
  • Foliated: Have layered or banded appearances (e.g., slate, schist).
  • Non-foliated: Do not have visible layers (e.g., marble, quartzite).
  • Index Minerals: Minerals that form only under specific temperature and pressure conditions.

Rock Cycle

  • Igneous rocks form from cooled magma/lava.
  • Sedimentary rocks form from compacted sediments.
  • Metamorphic rocks form from other rocks under heat and pressure.

Geologic History

  • Fossils: Preserved remains of past organisms.
  • Types of Fossils:
    • Body fossils
    • Trace fossils
    • Moulds and casts
  • Relative Age: Determined by the principle of superposition (older layers are below younger ones).
  • Fossil Record: Collection of all known fossils in rock layers. Shows changes in life over time.
  • Mass Extinctions: Events where many species die out in a short period, visible in the fossil record.