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19th November 2014 Dear Parent/ Carer, RE: Year 8 End of term exam and setting on 8th December Your son has been sitting a series of end of topic assessments for the content he has covered this term so far. Please note, as the term is not yet over, he will not have sat every assessment. Details about your son’s performance on each of the end of topic assessments he has sat so far and the average for that assessment in his class, will be sent home with your son this week. If your son is below the average for the class this is an indication that there is a strong possibility he may be moved down a set in January and if your son is well above the average this is an indication that there is a chance that your son may move up a set in January. Please note, if your son was absent for his end of topic assessment, his teacher will make time for him to complete it. Your son has an exam in the hall on Monday 8th December which will cover all content that he has been taught this term. The three homework booklets used this term detail the topics that have been covered. Attached to this letter are details about revision sources and summary sheets for topics taught this term. The outcome of this test in December, along with his maths assessment, will primarily be used to set your son in January. Please remember that setting is contextual, he will be set by comparing his mark with the others boys marks in his half of the year group. Please encourage your son to revise at home using the websites mentioned in his homework booklet, the revision materials included in this letter and his CGP revision guide and workbook. Yours sincerely, R Hall Miss R Hall KS3 Coordinator for Science [email protected] Useful Websites: There are plenty of websites that can help you revise the science you have been taught or to help you get ahead. Here are some of the better ones just google them to get to the website: BBC Bitesize KS3 Science Skoool Science Doc Brown KS3 Science CGP (if you have purchased the books use the code to access the online resources) Topic Pages In the CGP Revision Guide Health and Disease Microbes Electricity Electro Magnets Mass, Weight and Gravity Elements, Mixtures and Compounds Metals Reactions of Metals 9-11, 22, 28 14 162-166 169-171 138-139, 174 62-66, 68-70 75-76, 83-84, 93-95 Displacement 96-97 Pages In the Chapters In the CGP workbook Exploring science Electronic Book 29-30, 37-39 8C N/A 8C 202-208 7J 213-214 8J 215-216 9J 77-91 8E, 8F 95-97 8F 105-107, 120- 8F and 9F 121, 124-125 118, 126-129 9F Revision notes for Biology Topics: 8C Summary Sheets Microbes Microbes (short for micro-organisms) can only be seen using a microscope. There are three main types: viruses, bacteria and fungi. The most common fungus microbes are yeasts. Viruses are smaller than bacteria which are smaller than yeasts. Viruses are often not considered to be living because they do not carry out any of the seven life processes for themselves. Bacteria and yeast are important in making foods and drinks. Yeast is used to make bread dough rise. It uses oxygen, from the air found in pockets in the dough, for aerobic respiration. This process produces carbon dioxide which makes the bread rise. glucose + oxygen carbon dioxide + water (+ energy) (a sugar) Yeast are also used to make beer and wine. In this case there is no air and so they use anaerobic respiration. When yeast use anaerobic respiration it is called fermentation. The ethanol is a waste product of this reaction. glucose carbon dioxide + ethanol (+ energy) (a sugar) The numbers of an organism in an area are called a population. In good conditions (warm, moist, plenty of sugar) a population of yeast will grow rapidly. The population stops growing if something runs out (eg sugar). The thing that stops the population growing is called a limiting factor. Diseases Some microbes cause infectious diseases (diseases that can be spread from person to person). The microbes are said to infect you. The effects the microbes have on your body are known as symptoms. Microbes can be spread by the air, water, touch, food, animals and sex. Disease Microbe that causes it Symptoms How it is spread Virus Sore throat, running nose, fever Air Food poisoning Bacteria Vomiting, diarrhoea Food Cholera Bacteria Vomiting, diarrhoea Water Athlete’s foot Fungus Sore cracked skin between the toes Touch Colds and flu Some ways that diseases can be stopped from spreading are: • • • • • making sure sewage is treated and disposed of properly adding chlorine to water to kill bacteria pasteurising milk using disinfectants, antiseptics and soaps immunising people with vaccines. Your body has natural defences to stop microbes getting in (eg skin, mucus in the windpipe and nose, ciliated epithelial cells to sweep mucus along). Your body also has ways of destroying microbes. These include: • • • • a chemical in tears that kills some bacteria acid in the stomach that kills some bacteria white blood cells that engulf microbes other white blood cells that make antibodies to help destroy microbes. Babies do not have fully developed immune systems. Antibodies can pass through the placenta and are found in breast milk. These help the baby to fight infections. For many diseases, once you have had the disease (or been immunised) you will not get it again (e.g. chickenpox). This is because the antibodies against these microbes stay in the blood. Some diseases can be cured using antibiotics which are medicines which kill off bacteria. Some bacteria, however, are unaffected by antibiotics – they are resistant to them. Notes for Physics Topics: 7J Summary Sheets Electrical circuits Electricity is a flow of electrons. Electricity can flow through conductors but not through insulators. Metals are good conductors of electricity. Circuits A complete circuit is needed for electricity to flow. We use symbols when we draw circuits: Component Symbol Component cell variable resistor battery of cells motor bulb ammeter switch fuse Symbol resistor The current is the amount of electricity flowing in the circuit. The units for current are amps (A). Current is measured using an ammeter. The resistance of a circuit is a way of saying how easy or difficult it is for electricity to flow. • • high resistance = hard for electricity to flow = small current low resistance = easy for electricity to flow = large current Circuits can be series or parallel circuits. Series circuit • • • • Parallel circuit If one bulb breaks, all the others go off. • The current is the same everywhere. If you put more bulbs in they will be dimmer, because • it is harder for the electricity to get through. The resistance of the circuit is higher. • The voltage from the cell or power pack is divided between the components. • If one bulb breaks, the bulbs in the other branches stay on. The current splits up when it comes to a branch. The current in all the branches adds up to the current in the main part of a circuit. If you add more bulbs they stay bright. It is easier for the current to flow with more branches, because there are more ways for the electrons to go. The voltage is the same across all the branches of the circuit. Electricity and heat • • • When electricity flows through a wire, the wire can get hot. Hot wires are used in electric fires, irons and cookers. A fuse is a thin piece of wire that melts if too much electricity flows through it. It is used for safety. Electricity and your body Electrical signals in your body travel along nerves. If an electrical current passes through your body you may get an electric shock. This could burn you, or stop your heart or lungs working. 8J Summary Sheets Magnets and electromagnets Magnetism is a non-contact force. Magnets attract magnetic materials. Iron, nickel and cobalt are magnetic materials. Mixtures, like steel, that include a magnetic material will also be attracted to a magnet. Other metals, like aluminium, are not magnetic and will not be attracted to a magnet. Iron oxide is a compound that is a magnetic material. It is used to make video and music cassettes and computer discs. Magnetic materials can also block magnetism. You can make a magnet from a piece of iron or steel. • • • • The two ends of a bar magnet are called the north seeking pole and the south seeking pole or north pole and south pole for short. A north pole and a south pole attract each other. Two north poles or two south poles will repel each other. The space around a magnet where it has an effect is called its magnetic field. This is the shape of the magnetic field of a bar magnet. You can find the shape of the magnetic field using iron filings or using a plotting compass. The Earth has a magnetic field. A compass is a small magnet that always points north. But magnetic materials placed near a compass can change the direction that it points. Magnets can be used to sort iron and aluminium cans for recycling. Only the iron cans are attracted to the magnet. Magnets can also be used for holding fridge doors shut, and in compasses that sailors or walkers use. A wire with electricity flowing through it has a magnetic field around it. An electromagnet is a coil of wire with an electric current flowing through it. You can make an electromagnet stronger by: • • • increasing the number of coils of wire increasing the size of the current (by increasing the voltage) using an iron core. Electromagnets can be used for lifting things. They are also used in electric bells, relays and in video and music recording. Electromagnets are used to make bells work. A reed switch has two thin pieces of iron inside it. If a magnet is held near the switch, the pieces of iron are magnetised and touch each other. A reed switch can also be switched on using an electromagnet. Any switch that is worked by electricity is called a relay. Relays are used to make things safer. For example, the starter motor in a car uses a high current and needs thick wires for the current to flow through. A relay is used in a car so that the driver does not have to touch any part of the circuit that has a high current. 9J Summary Sheets Gravity and space Mass and weight The mass of something is the amount of substance or ‘matter’ it contains. It is measured in kilograms (kg). Weight is the force of gravity pulling on a mass. It is a force, so it is measured in newtons (N). Gravity Gravity is the force of attraction between two masses. The force of gravity is stronger if: • • the objects have large masses the objects are close together. On Earth, the gravity pulls on every kilogram of mass with a force of 10 N. Gravity is not as strong on the Moon, because the Moon has a much smaller mass than the Earth. If you went to the Moon your mass would not change, but your weight would be less than on Earth because the Moon’s gravity is weaker. If a rocket travels away from the Earth, the force of gravity gets less and less as it gets further from Earth. If it is heading for the Moon, it will eventually reach a place where the Earth’s gravity is cancelled out by the Moon’s gravity. After that, the Moon’s gravity will be pulling it towards the Moon. The Sun’s gravity keeps all the planets moving in elliptical orbits around it. If there was no gravity from the Sun, the planets would all fly off into space. The Earth’s gravity keeps the Moon in orbit around the Earth. Satellites A satellite is anything that orbits around a planet. The Moon is the only natural satellite of the Earth. Artificial satellites can be put into orbit around the Earth. They can be used for communications (transmitting telephone calls or television programmes), for navigation, or to take pictures of the Earth or the planets and stars. Satellites can also be put into orbit around other planets. They can take pictures and take measurements, and send all the information back to Earth. Changing ideas about the Solar System People have known that the Earth is spherical for thousands of years, but they have only believed that the Sun is at the centre of the Solar System for about 500 years. Early ideas had the Earth in the centre of the Solar System, with the Sun, the planets and the stars moving in circular orbits around the Earth. These ideas were used to make predictions about where the planets would be in the sky, but the predictions were not very accurate. Copernicus suggested that the Sun was in the centre of the Solar System, but his model still had the planets moving in circular orbits. The predictions made using this model were a bit more accurate, but there were still errors. Kepler suggested that the planets actually move in elliptical orbits around the Sun. His model could be used to make very accurate predictions. After Newton had worked out how Kepler’s model could be explained using his ideas about gravity, most scientists accepted that this was the correct way of thinking about the Solar System. Revision Notes for Chemistry Topics: 8E Summary Sheets Atoms and elements Elements An element is a simple substance that cannot be split into anything simpler by chemical reactions. Atoms are the smallest particles of an element that can exist. Atoms of one element are all the same, and are different from atoms of all the other elements. There are over 100 different elements. All the elements are shown in the Periodic Table. Each element has a chemical symbol, which is usually one or two letters. A symbol is written with the first letter as a capital, and the second letter is small. carbon C oxygen O nitrogen N hydrogen H gold Au silver Ag copper Cu aluminium Al Metals and non-metals The properties of a substance are the words that we use to describe it, or measurements that we can make on it. Metals and non-metals have different properties. Metals Non-metals good conductors of heat and electricity poor conductors of heat and electricity shiny dull solids with a high melting point (except for mercury) most are solids or gases found on the left-hand side of the Periodic Table found on the right-hand side of the Periodic Table three metals are magnetic no non-metals are magnetic metals can burn to form alkaline oxides non-metals can burn to form acidic oxides flexible brittle Compounds Elements can join together to make compounds. The name of the compound tells you the elements that are in it. Compounds made from two elements always have a name which ends in ‘-ide’. These elements join together … … to make these compounds carbon, oxygen carbon dioxide sodium, chlorine sodium chloride magnesium, oxygen magnesium oxide A chemical formula tells you the name and number of atoms in a compound. The smallest particle of many compounds is called a molecule. Molecules are made up of atoms. Some elements are also made of molecules. For example, a molecule of oxygen contains two oxygen atoms joined together. The formula is O2. Elements Compounds Mixtures atoms of helium (He) molecules of carbon dioxide (CO2) a mixture of helium and oxygen molecules of oxygen (O2) molecules of water (H2O) a mixture of carbon dioxide and oxygen a lump of carbon (C) a lump of sodium chloride (NaCl) a lump of bronze (an alloy of copper and tin) 8F Summary Sheets Compounds and mixtures Elements are simple substances which cannot be split up in chemical reactions. Atoms are the smallest particles of an element that can exist. Atoms of an element are all the same. Each element has its own chemical symbol. For example, the chemical symbol for oxygen is O. Some elements have their atoms joined to each other in small groups called molecules. Oxygen is an example. A molecule of oxygen consists of two oxygen atoms joined together. Compounds Elements can join together to make compounds. A compound contains two or more elements joined together. The name of the compound tells you the elements that are in it. Compounds made from two elements always have a name which ends in ‘-ide’. Many compounds exist as atoms attached to each other in small groups – molecules. A molecule of water. The chemical formula tells you the numbers of atoms of each element in a compound. Each element in the chemical formula is shown by its chemical symbol. For example: A compound always contains the same elements in the same ratio. The properties of a compound are different from the elements that make it up. For example, hydrogen is an explosive gas and oxygen will relight a glowing splint but water is a liquid which will put fires out. Chemical reactions Compounds can react chemically by mixing them with other chemicals, or by using heat or electricity. You can tell that a chemical reaction has occurred if there is a colour change or when a gas is given off. Most chemical reactions also involve an energy change. This is usually in the form of heat, but can also involve light being given off, for example, in burning (combustion). In a chemical reaction a new substance is always formed. Most chemical reactions are not easily reversed (they are irreversible). Some chemical reactions take place just by mixing. When you make a solid by mixing two liquids, the solid is called a precipitate. Other chemical reactions need energy to start them off. This energy can be in the form of heat, light or electricity. When you use energy to split up compounds they are decomposed. We can write word equations to show a chemical reaction. The chemicals that you start with are called the reactants. The chemicals at the end are called the products. For example: magnesium + oxygen reactants magnesium oxide product Physical changes In a physical change no new substance is formed. Melting, evaporating, condensing and freezing are all examples of physical changes. For example: Mixtures Elements and compounds can also be mixed together. A mixture is easier to separate than the elements in a compound. Soil, river water and sea water are examples of mixtures that occur naturally. Elements and compounds melt and boil at a fixed temperature. Mixtures do not have definite melting points and boiling points. Air is a mixture of gases – most of the air is nitrogen and oxygen. The gases in the air can be separated by fractional distillation. 9E Summary Sheets Reactions of metals and metal compounds The properties of a substance are the words that we use to describe it, or measurements that we can make on it. Metals and non-metals have different properties. Metals … Non-metals … are good conductors of heat and electricity are poor conductors of heat and electricity (except for carbon in the form of graphite which conducts electricity) are shiny are dull are solids, often with high melting points (except for mercury) are mostly solids or gases are found on the left-hand side of the Periodic Table are found on the right-hand side of the Periodic Table are sometimes magnetic – three metals are magnetic (iron, cobalt and nickel) are never magnetic form basic oxides form acidic oxides are rigid when thick and bendy when thin are brittle can be hammered into shape cannot be hammered into shape – the solid ones break Using metals Metals and non-metals have different uses because of their different properties. Aluminium is used for power lines because it is light and it is a good conductor of electricity. Iron and steel are used for bridges because they are strong and cheap. Gold is used for jewellery because it does not corrode and looks nice. Metals and acids Many metals react with acids. Some unreactive metals will only react very slowly with strong acids, some will not react at all. Some metals are more reactive and explode when added to acid. When a metal reacts with an acid, hydrogen gas is given off. The reaction also produces a compound called a salt. 9F Summary Sheets Patterns of reactivity Metals may react with substances around them in the environment such as air, water and acids. Some metals react very easily or quickly. They are reactive. Other metals do not react very easily and are described as unreactive. The most reactive metals are found on the left-hand side of the Periodic Table. Less reactive metals are found in the centre of the Periodic Table. Some gases are more reactive than others. In the air, oxygen is the most reactive gas. Nitrogen is not very reactive. When metals react with the oxygen in the air they form oxides. metal + oxygen metal oxide The metals that react quickly with air also tend to react with water. When metals react with water they form hydrogen gas and a metal hydroxide. metal + water metal hydroxide + hydrogen The metals that react with water also react very quickly with acids. Some metals that don’t react with water do react with acids. When metals react with acids, they produce hydrogen and a salt. metal + acid salt + hydrogen The name of the salt formed depends on the name of the acid: • sulphuric acid makes sulphates • • nitric acid makes nitrates hydrochloric acid makes chlorides. Reactivity Series Metals can be arranged in a Reactivity Series. The most reactive metals are placed at the top of the table. More reactive metals can displace less reactive metals from their compounds. In a displacement reaction, the more reactive metal will form a compound, and the less reactive metal is left on its own as the pure element. For example, iron is more reactive than copper, so it will displace copper from a compound. iron + copper chloride iron chloride + copper Zinc is more reactive than iron, so iron will not displace zinc from a compound. iron + zinc chloride no reaction You can use displacement reactions to work out the position of a metal in the Reactivity Series. For instance, zinc will displace lead from a compound, so we know that zinc is more reactive than lead. The Reactivity Series can also be used to predict whether reactions will occur. The reactivity of metals can be linked to their uses. Metals used for construction need to have a low reactivity, otherwise they will corrode away. Some metals, such as aluminium, have a natural protective oxide layer. Others, such as iron, have to be protected from corrosion, e.g. by painting. Many low reactivity metals have been known for hundreds or thousands of years. They can be extracted by heating their compounds in a fire. More reactive metals are extracted by electrolysis. This means that they have only been discovered in the last two hundred years, since the invention of the electric battery.