Study and revision skills INFO This section covers the following ideas and material: An introduction to revision methods, including • concept mapping, ? ow charts and mind maps • planned revision timing • practising examination technique. General study methods Organisation of study time The examinations are looming large. Suddenly you realise that you do need your notes and experimental work from the last year or two. Are they in good shape? Well...! It is worth remembering that revision is just that. It shouldn’t be the first time that you have tried to get to grips with a subject.
Organisation of study habits over a whole course is a vital part of being successful. This certainly means practical things, such as making sure that your notes are intact and readable. But it also includes making sure that you have understood the ideas and connections as you have covered a topic. Nothing can be worse than trying to learn masses of material that you don’t understand. The best preparation for an examination begins a long time before it! This spreads the load and lessens the tension as the examination approaches. Figure 1 summarises various aspects of preparing for examinations.
The coursework ‘arm’ emphasises not only the collection of good notes directly from class, but also the need to look at and use material from outside. Reading reference material and taking useful notes from it is a skill in itself. Table 1 outlines different methods of reading and their purpose. The first three methods are more appropriate to using books for reference. However, there is an increasing number of popular science books and magazines for which the last two methods are appropriate. In addition, there is an increasing amount of reference material now available on CD-ROM and, most significantly, the internet.
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You should find ways of using this material, as it provides a more interactive presentation of the material. The ability to make notes and topic summaries as you work through a course is important, as they can then be used as a starting point for revision. You should not think of practical work in chemistry as separate from other classwork. The ideas and detailed information from the practicals are important in reinforcing your understanding of a topic. Indeed, a particular experiment may help you to remember and understand a crucial idea – giving you a visual clue on which to ‘hang’ the idea in your memory. Cambridge University Press IGCSE Chemistry Study and revision skills 1 reading CD-ROM practical work classnotes COURSEWORK review cards summary sheets Information how much? when? spider diagrams Or gan isin topic lists mind maps gn ote s O n rga g isin tim e take breaks REVISION SKILLS use a timetable u St sk ill key words and ideas s dy bi ha stick to timetable or y ts M em suitable place regular reviews use summaries, spider diagrams and mind maps Figure 1 Revision involves organisation and the development of particular skills. alone or with a friend ime of day Type of reading skimming scanning reflective reading detecting bias reading for pleasure Method looking for the main topics looking for specific information reading carefully and thoughtfully, with attention to detail separating fact from opinion reading at own pace Purpose to gain an overall impression to find particular facts or conclusions to obtain a thorough understanding of a topic to form a decided impression of a controversial area to gain a feel for a subject, and for enjoyment Table 1 Different methods of reading and their purpose.
This book, and the accompanying materials, are aimed specifically at students taking the Cambridge IGCSE Chemistry course. This is a course and qualification with a very high international reputation. 2 © Cambridge University Press IGCSE Chemistry Study and revision skills INFO There is an excellent website for Cambridge IGCSE students, at: www. cambridgestudents. org. uk/subjectpages/chemistry/igcsechemistry Do take a good look at this website. You will ? nd copies of past papers, model answers to past questions, some simulations, and revision checklists based on the syllabus.
The tips from examiners are there to help you do well in the exam and are certainly worth taking note of. The website is worth visiting regularly, as new material and up-to-date papers are added to it. Getting started We have said it earlier, and it can be boring to repeat it, but it remains true all the same: to make sure of a high grade in your final examinations you will need to work hard throughout your course. Here are some tips to help you make the best use of the time you put in on your work in chemistry. Make sure you have a copy of the IGCSE Chemistry syllabus.
There is one provided on this CD which also gives you guidance as to where in the book the different topics are covered. It is important you know the course you are taking and the way in which you will be assessed. IGCSE exams aren’t just about learning facts. You need to be able to understand your work and become sufficiently confident in your understanding to answer questions about things you have never met before. You need to be able to transfer your knowledge in a particular area to an example that will be unfamiliar to you.
The IGCSE examiners will be setting questions to test three sets of skills (they are known as Assessment Objectives). These are: • Skill A: knowledge with understanding • Skill B: handling information and solving problems • Skill C: experimental skills and investigations. About 50% of all the marks in the exam are for skill A, 30% for skill B and 20% for skill C. Skill A is about learning and understanding all the facts and concepts in the syllabus. These are covered in your textbook, and your teacher will make sure you have met them all in class as your course progresses.
There are no crafty shortcuts, it is simply a case of getting your head down and working at these. Skill B is about using these facts and concepts and applying them to an unfamiliar context. It’s important that you become confident in tackling questions that, at first sight, look completely new. The workbook will give you lots of practice at this. Trying past question papers will also help to test this skill, but there will still be unusual material that you will meet for the first time in the exam. The following ‘model exam question’ is similar to the type of question found on an extended paper and will give you some idea of what to expect.
Cathodic protection of steel objects is not mentioned in the syllabus whereas sacrificial protection is. Yet here you are asked to compare the two using your knowledge and understanding of electrolysis. Skill C is about practical skills. You should have plenty of opportunity to do experiments in a laboratory throughout your course. The workbook also has exercises that will help you to improve your skills at handling and interpreting data obtained from experiments, and designing experiments. But make sure you gain the most you can from your practical sessions.
Chapter 12 gives you clear guidance about what is involved in the assessment of your practical work. © Cambridge University Press IGCSE Chemistry Study and revision skills 3 Model Q Questions For relevant material, see Chapter 9. Titanium is very resistant to corrosion. One of its uses is as an electrode in the cathodic protection of large steel structures from rusting. + power – steel oil rig which is cathode titanium anode seawater contains H+(aq), OH–(aq), Na+(aq), Cl –(aq) a Define oxidation and reduction in terms of electron transfer.
Oxidation is the loss of electrons Reduction is the gain of electrons HINT: Remember OIL RIG – to help remember ‘oxidation is loss; reduction is gain’  b The steel oil rig is the negative electrode (cathode) in this protective electrolytic arrangement. Name the gas formed at this electrode. Hydrogen HINT: Discharge of H+ ions from the seawater.  c Name one of the two possible gases formed at the titanium anode. Oxygen (or chlorine) HINT: Discharge of OH? ions or Cl? from the seawater.  d Explain why the oil rig does not rust.
T oil rig legs are the cathode in the cell that is set up (see diagram)he and oxidation does not take place at the cathode (electrons are moving towards the cathode, not away from it). HINT: See Chapter 4 – oxidation takes place at the anode in electrolysis; reduction takes place at the cathode. Do not confuse this with sacri? cial protection.  e Another way of protecting steel from corrosion that involves using another metal is sacrificial protection. Give two differences between sacrificial protection and cathodic protection.
Cathodic protection involves electrolysis and needs electricity; it uses an inert electrode (here made of titanium). Sacrificial protection needs a more reactive metal; this metal corrodes instead of the steel. Sacrificial protection does not need electricity. f What is the name of the method of rust protection that uses zinc? Galvanisation   4 © Cambridge University Press IGCSE Chemistry Study and revision skills Keeping up progress During the course you will be given work to do. Try to work steadily through all the necessary material throughout your course. It is really important that you keep up with this.
Don’t set out to make life difficult for yourself. Do make sure that you understand each piece of work you do. Research shows that we find it much easier to learn and remember things if we understand them. If there is something you don’t understand, make sure you do everything you can to put this right straight away. Quite often working through a topic with a friend will help. Use your school library or the internet. Be careful of the internet, though, as many chemistry sites are written for other courses in different countries. These can use different approaches and it is difficult to apply the explanations you see.
Ask your teacher for a (short) list of reliable sites you can go to regularly. Strategies of study Your study sessions should use a variety of techniques to aid your understanding and learning of the material. Simply reading over your notes is not a particularly productive strategy. Try to summarise topics as you read, then shorten the summary down to a set of key words. Having learnt these, try to reconstruct notes on the topic. Your learning and understanding can also be checked and developed by answering questions from past examination papers. Keep the length of time taken to answer questions in mind when testing yourself.
There is no point in preparing over-elaborate answers to short questions. An important aspect of understanding a topic is to ‘see the connections’ between the ideas involved. Establishing these links makes it so much easier to remember the details of a topic. Pictorial methods of linking ideas can be very useful for this. INFO The methods available include: • • • • ?ow charts concept maps Venn diagrams mind maps. The importance of all these methods is that they force us to sort out the material into key ideas, and then to establish the links between them.
It is useful to draw up the diagrams for yourself. Remember that your ‘maps’ may well differ from other people’s. Comparing notes with others, or even drawing them up together as a group, can also be very useful. Sharing ideas and comparing maps helps you to think things through. As you use these methods, you will develop greater skill in drawing them up. Flow charts are linear in their approach and work down from a major idea by a series of subdivisions. They are useful for emphasising the different types of chemical substance, for example (see examples of charts in Chapters 2 and 3 in the textbook).
Concept maps and mind maps are particularly useful for helping you to see the flow of ideas. In a concept map (Figure 2), the interlinking idea is written alongside the connecting arrow. © Cambridge University Press IGCSE Chemistry Study and revision skills 5 a combustion neutralisation precipitation synthesis redox are types of a catalyst speeds up a chemical reaction can be written down as a word or symbol equation word n tio equa sym bo equa l tion example: zinc + oxygen > zinc oxide 2Zn + O2 > 2ZnO these are elements this is a compound this means this means 2 atoms of zinc 1 molecule of oxygen is the process that positive ions undergo at the cathode during is the gain of ELECTROLYSIS transferred during ELECTRONS is the loss of is the opposite process to is the process that negative ions undergo at the anode during process used to extract metals in the BLAST FURNACE REDUCTION REDOX OXIDATION is a special form of is the opposite process to is the removal of is the addition of COMBUSTION OXYGEN element removed from metal ores by carbon in Figure 2 a Spider diagrams, and b concept maps involve organising ideas and their connections. reactions in which substances react with
Venn diagrams are useful for showing where different categories overlap. For example, the different ways in which we categorise reactions can result in overlaps. Figure 3 shows this. It also shows how the term ‘redox reaction’ covers a wide range of reactions. 6 © Cambridge University Press IGCSE Chemistry Study and revision skills NEUTRALISATION acid + base/alkali > salt + water ONLY PRECIPITATION forming an insoluble solid by a chemical reaction sodium thiosulfate + hydrochloric acid REDOX Synthesis Decomposition to elements Electrolysis Displacement Figure 3 A Venn diagram showing various types of reaction.
Can you think of examples to ? ll each space? (One has been done for you. ) Figure 4 shows a mind map covering aspects of the nature of atoms and molecules. This particular map covers a wide range of ideas – radiating from the central idea that matter is made up of very small particles (atoms or molecules, depending on the substance being talked about). The interconnections of ideas are emphasised. Putting the map on paper helps you to sort out your ideas! There are obviously overlaps between different topics. There are various pieces of mind-mapping software available (one was sed to construct Figure 4) and you can find these on the internet. However, it is important not to get over-involved in the processes of a particular IT package. In many ways the important thing about ‘mind-mapping’ is that it can be practised quite casually, and frequently, simply on a piece of ‘rough’ paper. Sketching different ‘mind maps’ on different topics is a way of looking at the subject from different angles to aid the memory. The main point is the thinking that is done while constructing the ‘map’. © Cambridge University Press IGCSE Chemistry Study and revision skills 7 escribes the states of matter and the movement of particles in these states the particles in matter are moving all the time ion init de f different substances contain different types of particles, e. g. atoms, ions or molecules Kinetic theory all matter is made up of very small particles the higher the temperature, the higher the average energy of the particles Diffusion does not take place in solids heavier particles move more slowly than lighter particles at the same temperature much slower in liquids than gases often energy given out various types, e. g. synthesis and decomposition usually not easily reversible
ATOMS AND MOLECULES new chemical substances formed Chemical reactions e. g. melting or dissolving Physical changes Dalton’s idea easily reversible, e. g. by cooling or evaporating no new chemical substances made Atomic theory atoms of different elements can combine to make the molecules of a compound a pure element contains only atoms with the same number of protons in the nucleus atoms of an element are each given their own symbol atoms are the smallest particles that take part in a chemical reaction the atoms of the different elements differ in size Figure 4 A mind map on ‘atoms and molecules’. © Cambridge University Press IGCSE Chemistry Study and revision skills (isotopes) (nucleus) (nuclear reactions) (balanced equations) physical properties depend on how the atoms are linked together (atoms can be subdivided) everything is made from about 100 elements, each made up of different atoms everything is made of invisibly small atoms, linked together in different patterns everything can be made from a few substances combined in different ways structures weigh the same as the total mass of their parts the total amount of matter stays the same (by mass) during chemical changes mount of matter stays the same (by atom count) during chemical changes chemical combinations of substances have different properties visible objects may be made of large numbers of very small invisible particles substances have physical properties magnifiers and microscopes often show that objects are made of smaller parts small parts can be put together in different ways to make different things water evaporates into the air all materials come from somewhere and must go somewhere PROPERTIES OF SUBSTANCES COMMON ELEMENTS ATOMS ARE INVISIBLY SMALL CONSERVATION OF MATTER
KEY Scientific ideas More general notions Storylines Figure 5 The different ‘storylines’ behind the maps branch into each other. Figure 5 shows how several ‘storylines’ can be linked together. This type of diagram can help you see the overall pattern of a section of the course you are taking and begin to see the ‘connections’ between ideas. The more connections, or associations, you can make between ideas, the more likely you are to understand and remember them. When a particular part of a course, or a particular topic, is finished it can be useful to produce a diagrammatic summary.
This helps reinforce the linked ideas while they are still fresh in your mind. The charts can provide a useful ‘checklist’ when it comes to revision. The next three charts (Figure 6a,b,c) show how parts of a course can be summarised. Figure 6a summarises a great deal of the material covered in Chapters 2 and 3, and Figures 6b and 6c flow into each other and show how much of chemistry develops from a consideration of the Earth’s resources. This ‘map’ of chemistry provides a context for your studies. © Cambridge University Press IGCSE Chemistry Study and revision skills 9 a SOLIDS LIQUIDS GASES
CHEMISTRY SECTION ONE PARTICLES ATOMS MOLECULES IONS ATOMIC STRUCTURE proton number Z – mass number A PROTONS ELECTRONS ORBITS (2,8,8) PROTONS +NEUTRONS NEUTRONS = A–Z p + 1 n o 1 e – EQUATIONS and CALCULATIONS Balancing Mr from Ar + % Quantities from equations Solids and gases Formulae from % Data Book FORMULAE 1 1840 CHEMICAL BONDS FORMING IONS Metals lose electrons Non-metals gain electrons GROUP 1 THE ALKALI METALS Reaction with Water Storage Variation down group Density m. p. IONIC COVALENT SHARING ELECTRONS GROUP 7 THE HALOGENS Reaction with iron Displacement Colour Variation down group m. . TRANSITION METALS Coloured compounds Catalysts High m. p. s NOBLE GASES No reactions Coloured lights METALS NON-METALS PHYSICAL PROPERTIES Malleable Conductors Strong High m. p. Shiny Alloys BURNING IN AIR and OXYGEN PHYSICAL PROPERTIES Brittle Poor conductors Low m. p. Dull REACTIVITY OF METALS BASIC OXIDES ACIDIC OXIDES Figure 6 a, b, c Flow charts can show very clearly the links between different areas of chemistry and help provide an overall pattern to a course. 10 © Cambridge University Press IGCSE Chemistry Study and revision skills b CHEMISTRY SECTION TWO
ALKALIS Basic Oxides + Water CHEMICAL REACTIONS ACIDS Acidic Oxides + Water REACTIVITY SERIES OF METALS AIR NEUTRALISATION H + +OH – H2O BONDS BREAK and FORM WATER ACID POTASSIUM SODIUM 14 pH WEAK WEAK STRONG pH STRONG NEW SUBSTANCES 8 6 1 Rapid Rapid BANG! ENERGY CHANGE CALCIUM © Cambridge University Press IGCSE Chemistry MAGNESIUM Quite Quick Rapid WATER pH7 SALT ALUMINIUM ZINC SULFATE Sulfuric Acid CHLORIDE Hydrochloric Acid NITRATE Nitric Acid Slow React with Steam Slow IRON ENDOTHERMIC Energy used and taken in EXOTHERMIC Energy produced and given out COPPER No Very Slow REVERSIBLE REACTIONS Can go both ways
SILVER No GOLD No N2 + 3H2 2NH3 DISPLACEMENT REACTIONS RATE(Speed) OF REACTION Reactions happen when particles collide. BUT they must collide hard enough. More collisions or harder collisions = Faster reaction. More reactive metals displace Less reactive metals from their compounds. BIG DIFFERENCE = FAST REACTION TEMPERATURE ALL REACTIONS Higher Temp Faster Particles Harder Collisions Faster Reaction Faster Reaction More Collisions More Particles More Conc REACTIONS WITH SOLUTIONS REACTIONS WITH SOLIDS Small Pieces More Surface More Collisions Faster Reaction CONCENTRATION SURFACE AREA
CATALYST SOME REACTIONS Catalyst not used up. Less energy needed More collisions succeed Study and revision skills ENZYMES Special Biological Catalysts in Living things. 11 c 12 BAUXITE ROCK Crust HEMATITE REDUCTION MALACHITE BLAST FURNACE ELECTROLYSIS OF MOLTEN OXIDE ALUMINIUM IRON LIME O2 STEEL CHEMISTRY SECTION THREE THE EARTH RAW MATERIALS N2 AIR O2 CO2 WATER H2O Photosynthesis Breathing IGNEOUS LIMESTONE HE AT © Cambridge University Press IGCSE Chemistry S U N SEDIMENTARY BLAST FURNACE + PURIFICATION BY ELECTROLYSIS Decay ering Erosion eat W sport Deposi an nta tio Tr Ceme tion n PLANTS Cooling Heat Pressure COPPER ANIMALS Death MAGMA METAMORPHIC M elti n g HALITE RockSalt NITRIC ACID LIME CEMENT GLASS SLAKED LIME CO2 O2 FOSSIL FUELS NITRATES IN SOIL NATURAL GAS AMMONIUM NITRATE N2 ELECTROLYSIS OF SOLUTION HABER PROCESS AMMONIA NITRIC ACID FERTILISER COAL PETROLEUM COKE HYDROGEN Fuel CHLORINE Water Treatment SODIUM HYDROXIDE Soap. BLEACH FUEL +or ELECTRICITY FRACTIONAL DISTILLATION ALKENES GAS PETROL NAPHTHA KEROSINE DIESEL LUBRICATING OIL FUEL OIL BITUMEN CRACKING PLASTICS
Study and revision skills The glossary – words are important Chemistry can be said to have a language of its own. As for the other sciences, there are special terms that need to be understood and remembered – an ‘atom’ is not the same thing as an ‘ion’ or a ‘molecule’. There are also some words that have a different slant on their meaning in chemistry. For example, saying that ethanol is ‘volatile’ does not mean that it is about to ‘freak out’, simply that it evaporates easily. Throughout the textbook, you will find words that have been highlighted in red bold type.
It would be useful to make a note of these and make sure that you are clear about their meaning. A glossary of these important chemical terms is also provided at the end of the book. The same glossary is also provided on this CD. If your first language is not English – and possibly even if it is – it would be useful to keep your own ‘chemical vocabulary’ book to help you to learn and understand the terms used in this subject. This should help you to understand questions clearly and not get tied up in confusing ‘waffle’ in your answers. © Cambridge University Press IGCSE Chemistry Study and revision skills 13
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