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Revision for Essa

Revision for Essa. Year 7. Working as a scientist. Identify common lab equipment Hypothesising, observing, inferring and concluding Using thermometers Format for report writing Measuring mass and volume Fair testing (controls and variables). Common lab equipment. C ommon lab equipment.

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Revision for Essa

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  1. Revision for Essa Year 7

  2. Working as a scientist • Identify common lab equipment • Hypothesising, observing, inferring and concluding • Using thermometers • Format for report writing • Measuring mass and volume • Fair testing (controls and variables)

  3. Common lab equipment

  4. Common lab equipment

  5. Hypothesising, observing, inferring & concluding • Observing – things or events that you notice. Eg. footprint, smell of perfume, sound • You infer something when you use your observation AND previous knowledge to explain something • Hypothesis – educated guess • Conclusion – final outcome of an investigation

  6. Using thermometers • A thermometer is used to measure temperature in degrees Celsius (˚C) • When reading a thermometer you must have your eyes level with the top of the of the column (of mercury or alcohol).

  7. Using thermometers

  8. Format for report writing • Aim: A short statement about what you are trying to find out. Must start with the word TO.Eg. To determine the battery brand which will last the longest in a clock radio. • Hypothesis: Your best educated guess of what you think you will discover. DO NOT USE THE WORDS ‘I THINK’ OR ‘I RECKON’.Eg. Duracell batteries will last the longest in a clock radio.

  9. Materials: A list of all the equipment/chemicals to be used. (This is sometimes called apparatus). • Method: A set of steps outlining how to do the experiment. Eg. 1. Pour 100ml of water into a 250ml beaker2. ….. • Results and observations: a presentation of your data – this usually includes a table and a graph. • Discussion: An explanation of your results. • Conclusion: A brief account of what you found out. Your conclusion should answer your aim.Eg. Everlast batteries lasted the longest in a clock radio.

  10. Measuring mass and volume • Mass = how much matter there is an object or substance. The standard unit of mass is the kilogram (kg). • We use a triple balance beam to measure mass.

  11. Measuring mass and volume • Volume is a measure of the amount of space that an object or substance occupies. The standard unit of volume for liquids is the litre (L). • To measure volume we use calibrated glassware (measuring cylinder, pipette).

  12. Measuring mass and volume

  13. Measuring mass and volume

  14. Fair testing (controls and variables) • In a fair test all conditions (variables) except the one being tested should be the same. • Independent variable: The ONE thing you change • Dependent variable: The thing you measure (eg height, weight, time) • Controlled variables: everything else that must remain constant.

  15. Separating mixtures • Terms: solution, solute, solvent, dissolve, soluble, insoluble, concentrated, dilute, saturated, sediment/precipitate. • Separation techniques: crystallisation, evaporation, filtration, decanting, distillation, centrifuging, chromatography

  16. Key terms • Solution: a mixture of one substance dissolved in another. • Solvent: The substances in which a chemical can dissolve (usually the liquid). • Solute: The substance that dissolves (usually the solid). FOR YOU TO DO: • What is the solute and solvent in the following:milo, cup of coffee, swimming pool water, sea water?

  17. Key terms • Soluble: substances which dissolve in a liquid. • Insoluble: substances which do not dissolve in a solvent. • Concentrated: more solute is dissolved in the solvent. • Dilute: less solute is dissolved in the solvent. THINK OF CORDIAL: The more cordial you add, the more concentrated your drink is!

  18. Key terms • Saturated: When no more solute can be dissolved in a liquid. Think of your clothes being saturated – you cant get any more wet! • Sediment: particles that do not mix and settle to the bottom (like sand in water) • Suspension: when the insoluble substance is dispersed (spread) throughout the liquid, making it cloudy

  19. Separation techniques • Evaporation: when one substance is heated and evaporates. Salt and water. • Crystallisation: separating sugar from water. • Filtration: uses filter paper to separate insoluble substances from soluble substances.

  20. Separation techniques • Distillation: Separates based on differing boiling points.

  21. Separation techniques • Decanting: Separates a liquid and a sediment – by allowing the sediment to settle to the bottom of the container and the liquid is poured off the top.

  22. Separation techniques • Centrifuging: Spinning a mixture quickly – forcing the heavier substances to the sides. (eg washing machine) • Separating funnel: an apparatus used to separate 2 liquids that do not mix (eg oil and water)

  23. Separation techniques • Chromatography: paints, inks and dyes are often mixtures of substances that have different colours – separating these colours out is chromatography.

  24. Cells • Microscopes (light and electron, monocular and stereo) • Parts of a microscope • How to use a microscope • Calculating total magnification • Rules for sketching specimens • Staining specimens • Cells: look at plant and animal cells • Basic organelles: cell wall, cell membrane, nucleus, vacuole, chloroplast, mitochondria, cytoplasm • Unicellular vs multicellular organisms

  25. Microscopes • Light microscope: uses light rays to see an image. • Electron microscope: uses electrons to see an image.We use light microscopes at school! • Monocular microscope: you use only one eye. • Stereo microscope: you use both eyes.

  26. Microscopes

  27. Calculating total magnification • To calculate the total magnification, you must multiply the magnification of your eyepiece lens and the objective lens.

  28. Rules for sketching • Use a sharp pencil • Draw only the lines you see • Your diagram should take up about a third of the page • Record the total magnification • State the name of the specimen and the date observed • Label what you can

  29. Staining specimens • Many specimens are colourless when viewed down a microscope, so specimens are often stained (or coloured) to make them easier to see.

  30. Cells – plant and animal • All living things are made of cells. • The tiny ‘organs’ of a cell are called the organelles. • Plant cells have different organelles to animals cells.

  31. Cell organelles • Nucleus: control centre of cell • Cell membrane: controls what goes into and comes out of cell. • Cytoplasm: where chemical reactions take place. • Cell wall: protection, support and shape. • Mitochondria: supplies energy. • Chloroplasts: photosynthesis. • Vacuole: large cavity (hole) storing water and other substances.

  32. Plants cells vs animal cells

  33. Plants cells vs animal cells

  34. Unicellular vs multicellular • Some organisms are made up of a single cell – they are described as unicellular. • Multicellular organisms are made up of many cells with different types of cells doing different jobs. • What are some of the cells making up humans?

  35. Solids, liquids and gases • What is matter/states of matter • What is volume, how can we measure volume • Particle model • Changing states: melting, freezing, evaporation/ boiling, condensation, sublimation, • Water cycle: cloud and fog • Convection, conduction, radiation

  36. What is matter/states of matter • Matter is anything with mass and volume. • Matter can exist in 3 states: solid, liquid and gas. • Water is a liquid. What is the name of the solid and gas forms of water?

  37. States of matter • The different states of matter have different properties.

  38. Volume • The amount of space taken up by a solid, liquid or gas is called its volume. • The volume of liquids is measured in litres or millilitres. • The volume of solids are measured in cubic metres or cubic centimetres. • How can you measure the volume of an irregular shaped rock?

  39. Particle model There are 4 parts to the particle model: • All substances are made of tiny particles • The particles are attracted towards each other and surrounding particles • The particles are always moving or vibrating. • The hotter the substance is, the more energy the particles contain and the faster they move!

  40. Balloon experiment

  41. Changing states

  42. The water cycle • Cloud: When water vapour becomes cold enough it condenses to form clouds. • Fog: Clouds close to the ground.

  43. Convection, conduction & radiation

  44. Classification • Living, nonliving, dead • Dichotomous keys • 5 vertebrate groups

  45. Classification • Classify means to sort into groups. • Taxonomy is the science of classifying organisms. • One feature that can be used in forming groups is whether something is living, non living (was never alive) or dead. • Sort the following: sun, leaf, bird, rose, water, wooden table.

  46. Dichotomous keys • There are only 2 choices at each branch.

  47. Vertebrate groups • Vertebrates: animals which have internal skeletons or backbones. • Invertebrates: animals which have an external skeleton or no skeleton. • 5 vertebrate groups: mammals, aves, reptiles, amphibia, fish.

  48. Forces • Speed • Types of forces: gravity, magnetic, electrostatic • Contact and non-contact forces, buoyancy, friction

  49. Speed • Speed is a measure of how quickly distance is covered. • Speed: distance ÷ time • Units: km/hr, m/sec, cm/min…..

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