Physics and Chemistry S E C O N D A R Y 2 This book is a collective work , conceived, designed and created by the Editorial depar tment at Santillana , under the super vision of Teresa Grence. WRITERS Annabel Maybank María del Carmen Vidal EDITORS Bárbara Braña Dave Wile EDITORIAL MANAGERS Nuria Corredera David Sánchez PROJECT DIRECTOR Antonio Brandi BILINGUAL PROJECT DIRECTOR Margarita España Do not write in this book. Do all the activities in your notebook.
Contents Uni t Learning s i tuat ion C H A L L E N G E Susta inabl e Deve l opment Goa l s (SDG ) and the i r target s 1 Matter and measurement 8 Reduce the production and consumption of packaging SDG 12: Responsible consumption and production 2 States of matter 32 Make an SOS video: the Earth's ice is melting SDG 13: Climate action 3 Diversity of matter 56 Take part in a science and healthy cooking competition SDG 2: Zero hunger Target 2.2 4 Changes in matter 76 Present the life cycle of a raw material SDG 8: Decent work and economic growth Target 8.4 Target 13.3 Target 12.5
Essent i a l knowl edge Sc i ent i f i c work Cr i t i ca l think ing 1. Matter and its properties 2. Measurement 3. Measuring instruments 4. Indirect measurements 5. Converting units - Detect air - Measure the volume of a drop of water - Measure surface area by weight - Measure density Can we recycle disposable drink cups? Is it worth separating waste at home? 1. Physical states of matter 2. Kinetic theory and states of matter 3. Gas laws 4. Changes of state 5. Kinetic theory and changes of state 6. States of water and meteorology - Analyse a change of state in water: from a solid to a liquid - Analyse a change of state: from a liquid to a gas - Study water evaporation - Analyse the effect of pressure on boiling Do earthenware jugs cool water? 1. Pure substances and mixtures 2. Homogeneous mixtures and heterogeneous mixtures 3. What makes up matter 4. The periodic table of elements 5. How chemical compounds are named - Make mayonnaise - Distinguish a mixture from a pure substance - Distinguish a mixture from a compound Can water and fat mix? 1. Physical changes and chemical changes 2. Separation of the components of a mixture 3. Chemical reactions 4. How matter is arranged 5. The most common chemical compounds - Observe changes in matter - Crystallise a substance - Carry out a chromotography experiment Are all fires put out with water?
Contents Uni t Learning s i tuat ion C H A L L E N G E Susta inabl e Deve l opment Goa l s (SDG ) and the i r target s 5 The forces of nature 98 Develop models to explain the forces of nature SDG 4: Quality education Target 4.1 6 Energy 126 Make a podcast about how to obtain energy without harming the environment SDG 7: Affordable and clean energy Target 7.1 7 Temperature and heat 150 Design homes with good thermal insulation SDG 11: Sustainable cities and communities Target 11.3 8 Light and sound 174 Make a guide to eye and ear care SDG 3: Good health and well-being Target 3.d Annex 198
Essent i a l knowl edge Sc i ent i f i c work Cr i t i ca l think ing 1. The movement of celestial bodies 2. Gravity: the force that makes celestial bodies move 3. The Universe 4. Revolution and rotation 5. Electric charge and electric force 6. Magnetism 7. The relationship between electricity and magnetism 8. Nuclear forces - Use an electroscope or a versorium to detect an electric charge - Carry out Ørsted's experiment - Check the functioning of an electromagnet - Generate an electric current with a magnet 1. What is energy? 2. Forms of energy 3. Properties of energy 4. Energy sources 5. The environmental impact of energy 6. The energy we use 7. Energy saving and sustainable development - Analyse uses of energy - Analyse energy transformations in a solar thermal power station - Interpret world energy balances Do solar panels only work on sunny summer days? Should we turn off the heating when we leave the house or is it better to leave it on? 1. Temperature 2. The thermometer 3. What is heat? 4. Effects of heat. Temperature change 5. Effects of heat. Change of state 6. Effects of heat. Expansion 7. How heat spreads - Identify hot and cold objects - Make an expansion thermometer - Analyse energy exchanges - Determine the temperature of thermal equilibrium - Test how the temperature increases in different bodies that receive the same heat - Test the change of state in the same mass of different substances that receive the same heat - Test heat conduction in metals - Analyse how heat spreads Can ice burn? 1. What is a wave? 2. Sound waves 3. Light waves 4. Properties of waves - Observe the shape of a wave - Test to see if light travels in a straight line - How shadows and shade are formed Does the light from a mobile phone prevent us from falling asleep? Periodic table of elements
Education is a long road that lasts a lifetime. Follow the WORLD MAKERS learning path to create a more equal, fair and sustainable world. Learning path L E A R N I N G S I T UAT I O N Water has properties that make it essential for life to exist. On Earth , water is found in three states: ice, at the poles and in glaciers; water, in seas and rivers; and steam, in geysers. Ice regulates the Earth's temperature by ref lecting part of the solar radiation that reaches it. Recent studies show a significant loss in the surface area and thickness of existing ice sheets. We must send an SOS to prevent this and the serious consequences it will have on our planet. You are going to make a video to spread this message. Take act ion When making your video, you should use all the information you have studied in this unit about states of matter and changes in state. Your scientific knowledge will strengthen your message and help you to complete your challenge. Target 13.3: "Improve education , awareness-raising and human and institutional capacity on climate change mitigation , adaptation , impact reduction and early warning." States of matter 2 How many states is matter found in? How can we make matter change from one state to another? When matter changes state, does it experience a physical or chemical change? WORK WITH THE IMAGE A wide range of living things live at the poles. How will the melting ice affect their existence? Will they be able to survive? WORK WITH THE IMAGE Technology is enabling us to construct more comfortable buildings that use less energy. One of these advances is reflective roofs. They can reflect up to 70 % of the solar energy that reaches them and reduce the temperature inside by up to 10 °C. What colour is the reflective paint that is being applied to the roof ? Why has this colour been chosen? There is a sheet of insulating material under the paint. What would happen without this sheet? Compare the reflective roof with ice sheets. Why is the size of its surface area important? Why is its thickness important? IN THIS UNIT… Physical states of matter Kinetic theory and states of matter Gas laws Changes of state Kinetic theory and changes of state States of water and meteorology Make an SOS video: the Earth's ice is melting C HALLE NGE L E T ' S G E T S TA R T E D 33 32 STATES OF MATTER PHYSICS AND CHEMISTRY REVISION CHANGES IN STATE Matter can change from one physical state to another. For example, when we heat ice, first it turns into water and then into steam. If we cool the steam, the opposite changes occur. 1 In a table in your notebook, classify each substance as a solid, liquid or gas, according to its state at room temperature. wood natural gas oil water aluminium oxygen alcohol carbon dioxide sand 2 After leaving some ice cubes on a table for a while, they turned into water. How can this happen if they have not been heated? A C T I V I T I E S Matter that can be moved from one place to another without changing its shape or size. A solid does not need to be in a container. Solid Matter whose shape changes as it moves from one container to another. It always occupies the same volume. A liquid needs to be in a container, which can be open. Liquid water, oil , alcohol , etc. Matter whose shape and volume can be changed by squeezing, reducing or enlarging the container. A gas must be in a closed container. Gas ice, sugar, metals, etc. steam, air, butane gas, etc. 6. …it turns into ice. 5. …it turns into liquid water. If we put it in the freezer… 4. If we leave the steam to cool… COOLING 1. When we heat ice… HEATING 2. …it turns into water. If we continue heating it… 3. …it boils and turns into steam. 34 LEARNING SITUATION. THE CHALLENGE 1 THE SUSTAINABLE DEVELOPMENT GOALS 2 CORE SKILLS 3 Remember what you already know about the topic, your previous knowledge acquired in previous years, in other units or in your own daily life. Think about an everyday life situation and put yourself in the place of the characters who present it. Contribute to the achievement of one or several targets of the Sustainable Development Goals (SDGs). Analyse examples of SOLVED PROBLEMS, then apply what you have learnt to solve the activities. Think and express your analytical side by doing the different ACTIVITIES. Critical thinking. Discuss whether the information is true or not. In the TRUE OR FALSE? section, you will find suggestions for learning how to create truthful content and for deconstructing fake news and myths. Review in the initial REVISION section what you already know and relate this knowledge to what you are going to learn. Research, think and then answer the questions that will help you complete the challenge and acquire core skills. 2 Study water evaporation Materials Beaker of water Thermometer Stand Hot plate Stopwatch Stopwatch Stand Thermometer Beaker Hot plate Represent the data on a temperature–time graph. Look at the example in the table. Draw a graph Time (min) 0 1 2 4 6 8 10 12 Temperature (°C) 24 28 40 70 100 100 100 100 22 Answer. a) What is the boiling point of water? b) How do you know? 23 Could water reach a temperature above 100 °C? Why? 24 Why must the thermometer not touch the bottom of the beaker? What would it record in this case? 25 What will happen if we turn the heat of the hot plate up or down? Can the thermometer record a temperature above 100 °C? Explain your answer. Conclusions Hang the thermometer so the bulb is in the middle of the water. Turn on the hot plate. Start the stopwatch. Write down the temperature at different times. Record the information in a table. Continue to record the time and temperature for a few more minutes, while the water is boiling. Steps 1 2 3 43 Do experiments and carry out simple practical activities. Complete the steps by applying what you have learnt. Acquire essential knowledge from content explained in a very clear way and with strong visual support: photos, drawings, diagrams, etc. ESSENTIAL KNOWLEDGE 4
With the STUDY NOTES you can revise the key concepts of each unit and check your progress. C O N C E P T M A P > Copy and complete the concept map. it is everything that occupies … and has mass … : has defined boundaries … : depend on the size. Example: mass intensive: do not depend on the … . Example: density property of matter that can be … MEASUREMENT quantity International System of Units (SI) defines the … for units material system: has no … … amount of a quantity used as a reference MATTER PROPERTIES OF MATTER quantitative: described with a number and a … . Example: mass … : described with words. Example: colour … : they can have any value. Example: mass specific: they help us to … matter. Example: density specific properties density: d = m / V melting point … solubility in water … hardness MEASURING INSTRUMENTS direct measurement … measurement length: ruler … : scales volume: graduated … … : stopwatch temperature: … surface area density length: metre (…) … : kilogram (kg) time: … (s ) conversion … converting units 7 1 Aplicaciones de la nanotecnología Applications of nanotechnology Nanotechnol ogy Nanotechnology is the branch of technology in which materials and structures have dimensions that are measured in nanometres. It has applications in physics, chemistr y and biology. Electronics Carbon nanotubes are close to replacing silicon as a material for making smaller, faster and more ef ficient microchips and devices. They are also used to make lighter, stronger and more conductive quantum nanowires. The properties of graphene make it an ideal candidate for the development of f lexible touchscreens. Biomedicine The properties of some nanomaterials make them ideal for improving early diagnosis and treatment of neurodegenerative diseases or cancer. They can attack cancer cells selectively without harming other healthy cells. Some nanoparticles have also been used to improve pharmaceutical products such as sunscreen . Environment Some of the environmentallyfriendly applications of nanotechnology are air purification with ions, wastewater purification with nanobubbles, and nanofiltration systems for heavy metals. Nanocatalysts are also available to make chemical reactions more ef ficient and less polluting. Textiles Nanotechnology makes it possible to develop smart fabrics that do not stain or wrinkle. It also produces stronger, lighter and more durable materials to make motorcycle helmets or sports equipment. Food In this field , nanobiosensors could be used to detect the presence of pathogens in food . Nanocomposites could improve food production by increasing mechanical and thermal resistance and decreasing oxygen transfer in packaged products. Energy A new semiconductor developed by Kyoto University ( Japan) makes it possible to manufacture solar panels that double the amount of sunlight converted into electricity. Nanotechnology lowers costs, produces stronger and lighter wind turbines, and improves fuel efficiency. It can also save energy, thanks to the thermal insulation of some nanocomponents. www.iberdrola .com (Adapted) 12 FINAL ACTIVITIES 5 Study the information and apply your essential knowledge to different contexts and situations. Do the activities in the ORGANISE YOUR IDEAS and CHECK YOUR PROGRESS sections. Critical thinking. Analyse a news article and answer the questions that will help you to think about and show your reasoning. Make connections between Physics and Chemistry and other subject areas to help you understand the world you live in. Complete the challenge and tell other people what you have achieved. Share the results with the people around you. In this way, you are contributing to the construction of a better world for everyone. 58 S C I E N C E A N D A R T. Have you ever wondered how the metal sculptures we see in museums, squares and buildings are made? The lost-wax casting technique is used. It can be applied to sculptures, jewellery or metallic pieces. This technique follows these steps: 1. A prototype is made in a soft material. It can be made directly or by using a 3-D design program. 2. A mould of the prototype is made. This will be the negative of the piece. Traditionally, a plaster mould was made. Nowadays, it can be made with a 3-D printer, in plastic or silicone. The mould can be used repeatedly to make identical pieces. 3. The mould is filled with wax. 4. The wax object is covered with a heat-resistant paste and left to set. 5. The wax is replaced with molten metal. 6. Finally, when it has cooled, the mould is broken to reveal the metal sculpture. Unwanted extra bits are then removed and the piece is polished. a) In this process, there are two materials that change state. What are they? What change do they go through? b) Find out the temperature at which these changes of state occur and explain the difference between them. c) To make the cast (model) of the sculpture, a mixture of water and plaster is used. This is then left to solidify. Is this a physical change of state? How do you know? 59 When you take a shower, especially in winter, the glass or mirrors in the bathroom steam up. Why does this happen? Copy the correct statements in your notebook. The hot water from the shower produces steam, which condenses when it touches the cold surface of the mirror. The change of state that occurs on the surface of the mirror is evaporation. The change of state that occurs on the surface of the mirror is condensation. For the steam to condense, the surface of the mirror must be at a lower temperature than the steam. For the steam to condense, the surface of the mirror must be at a higher temperature than the steam. 60 When gently heating chocolate, we observe that: It starts to melt at 28 ºC and it is completely melted at 50 ºC. The temperature has continuously increased. Analyse the experiment and answer. a) Does chocolate have a specific melting point? b) Is chocolate a pure substance? c) Some adverts for chocolates say "they melt in your mouth". Interpret this expression. 61 In your notebook, match the explanations of the states of water to the meteorological phenomena they produce. Frozen water drops that increase in size and fall under their own weight. Snow When it is very wet and cold, water condenses or solidifies. Respiration vapour The condensation of the air expelled by living things. Hail The water in clouds freezes and small ice crystals fall. Contrails The condensation of water in the atmosphere that forms drops. Dew and frost The crystallisation of water vapour coming out of a plane's engines. Clouds c h e c k yo u r p r o g r e s s 1 2 54 53 This graph shows the cooling of a gas in a closed tube. T (°C) 100 80 50 0 t (min) 30 20 10 0 In your notebook, indicate which of these statements is false. a) After 8 min, all the gas has turned into liquid. b) After 5 min, there is only gas in the tube. c) When the tube has cooled to 50 °C, there is only liquid inside. If we let the tube reach 0 °C and then heat it again, at what temperature will the liquid inside boil? 54 The steam that a pan of boiling water produces is at 100 °C. However, the steam that the hot water in a shower produces is not at 100 °C. How is this possible? Indicate the correct answer. Because the change in the hot shower water from a liquid to a gas is not an example of boiling, but evaporation. Because the steam the hot water produces has not yet changed state. Because the water in the shower is not a pure substance and its boiling point is much lower. 55 Indicate in your notebook in which of these cases the clothes will dry soonest. Explain your answer. 56 Read the news article and answer the questions. Misting systems: the miraculous mist keeps your home cool In hot weather, there is nothing better than water for reducing the temperature. It is clear and simple. When temperatures start to rise, using misting systems is the best way to enjoy outdoor plans. They are similar to a watering system, spraying water in ver y fine drops. When these drops come into contact with the air, they evaporate quickly, absorbing the heat in the atmosphere. They can lower the temperature by up to 10 °C. elmundo.es (Adapted) a) Explain how a misting system works. What is the vapour it produces? b) Indicate the highest temperature reached in your region in summer. At that temperature, does water evaporate or boil? Explain your answer. c) When water changes from a liquid to a gas, does it absorb or release heat? d) Why does the atmosphere cool when the sprayed water evaporates? e) Can we obtain the same effect by placing a bowl of water near us? Why? f ) Indicate in which other places it would be useful to use misting systems to lower the temperature. 57 One of the serious problems that Sustainable Development Goal (SDG) 13 is trying to prevent is the melting of the poles and glaciers. Studies show that the temperature of the oceans has increased in recent years. a) How does the temperature of the oceans affect the melting of ice? What change of state occurs? b) What consequences do you think melting ice can have? c) Research the preventative measures proposed in the SDGs. Write ten recommendations to put up in the classroom. 2 A B C D 53 62 Rime ice is a phenomenon that occurs when there are fog banks, high winds and the temperature is very low. Something similar to what is shown in the photo can form. Compare it with frost and explain: a) What change of state occurs in each case? b) Which of these phenomena can appear on the upper part of trees? Why? c) Why doesn't frost form large horizontal ice needles? 63 Read the news article and answer the questions. "Alarming" rain recorded for the first time at one of Greenland's highest points No one knows when it last rained in this remote part of the Earth . At the Summit of Greenland, at an altitude of 3 216 metres and with temperatures below freezing (almost) all the time, there is a research station . Engineer Zoe Cour ville told The Washington Post that on 14th August 2021 "it rained all day". At one point, the thermometer read 0.48 °C. It is the fourth time in the last 25 years that the temperature has been above freezing. BBC News Mundo (Adapted) a) Review the text and explain why the rain at the Summit of Greenland was such important news. b) Does it always rain when the temperature of the atmosphere rises above 0 °C? Explain your answer. c) The image shows the amount of ice in Antarctica on 13th September 2020. How did it change between the period 1981-2010 and 2020? What do you think caused this change? Explain your answer. d) One consequence of the melting ice at the poles is the rising sea level. Use your knowledge of the properties of water in solid and liquid states to explain this fact. 2 SOS video: the Earth's ice is melting Work as a class to write a script for your documentary. Explain, using scientific knowledge, why we need to prevent the ice on our planet from melting. Collect images to support different parts of the script. You can include opinions from scientists or experts. Draw diagrams to explain what is happening. Design the labels and sound. You can narrate it or use images with background sound. Share your documentary on social media. Collect feedback from viewers. Design an advert to promote it. Doing this challenge, you have learnt about the states of matter and their characteristics. You also now know why matter changes state and how this relates to the climate. 2020 Average ice boundary between 1981 and 2010 W E L L D O N E ! CHALLENGE 55 In addition, there is helpful support material available: You can consult the PERIODIC TABLE at the end of the book. A notebook with INNOVATIONS IN SCIENCE helps you to understand the importance of science in our society. THE CHALLENGE 6 Periodic table of elements Annex 2 GROUP 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 PERIOD 1 1.008 1 H Hydrogen 4.003 2 He Helium 2 6.94 3 Li Lithium 9.012 4 Be Beryllium 10.81 5 B Boron 12.01 6 C Carbon 14.01 7 N Nitrogen 16.00 8 O Oxygen 19.00 9 F Fluorine 20.18 10 Ne Neon 3 22.99 11 Na Sodium 24.31 12 Mg Magnesium 26.98 13 Al Aluminium 28.09 14 Si Silicon 30.97 15 P Phosphorous 32.06 16 S Sulphur 35.45 17 Cl Chlorine 39.95 18 Ar Argon 4 39.10 19 K Potassium 40.08 20 Ca Calcium 44.96 21 Sc Scandium 47.87 22 Ti Titanium 50.94 23 V Vanadium 52.00 24 Cr Chromium 54.94 25 Mn Manganese 55.85 26 Fe Iron 58.93 27 Co Cobalt 58.69 28 Ni Nickel 63.55 29 Cu Copper 65.38 30 Zn Zinc 69.72 31 Ga Gallium 72.63 32 Ge Germanium 74.92 33 As Arsenic 78.97 34 Se Selenium 79.90 35 Br Bromine 83.80 36 Kr Krypton 5 85.47 37 Rb Rubidium 87.62 38 Sr Strontium 88.91 39 Y Yttrium 91.22 40 Zr Zirconium 92.91 41 Nb Niobium 95.95 42 Mo Molybdenum ( 97) 43 Tc Technetium 101.1 44 Ru Ruthenium 102.9 45 Rh Rhodium 106.4 46 Pd Palladium 107.9 47 Ag Silver 112.4 48 Cd Cadmium 114.8 49 In Indium 118.7 50 Sn Tin 121.8 51 Sb Antimony 127.6 52 Te Tellurium 126.9 53 I Iodine 131.3 54 Xe Xenon 6 132.9 55 Cs Caesium 137.3 56 Ba Barium 57-71 Lanthanoids 178.5 72 Hf Hafnium 180.9 73 Ta Tantalum 183.8 74 W Tungsten 186.2 75 Re Rhenium 190.2 76 Os Osmium 192.2 77 Ir Iridium 195.1 78 Pt Platinum 197.0 79 Au Gold 200.6 80 Hg Mercury 204.4 81 Tl Thallium 207.2 82 Pb Lead 209.0 83 Bi Bismuth (209) 84 Po Polonium (210) 85 At Astatine (222) 86 Rn Radon 7 (223) 87 Fr Francium (226) 88 Ra Radium 89-103 Actinoids (267) 104 Rf Rutherfordium (270) 105 Db Dubnium (269) 106 Sg Seaborgium (270) 107 Bh Bohrium (269) 108 Hs Hassium (278) 109 Mt Meitnerium (281) 110 Ds Darmstadtium (281) 111 Rg Roentgenium (286) 112 Cn Copernicium (284) 113 Nh Nihonium (285) 114 Fl Flerovium (289) 115 Mc Moscovium (293) 116 Lv Livermorium (293) 117 Ts Tennessine (294) 118 Og Oganesson 40.08 20 Ca Calcium Atomic mass (u) Symbol (synthetic elements, such as Tc, are represented by white letters) Name Atomic number Although it is on the left-hand side of the periodic table, hydrogen is not a metal. METALLOIDS NONMETALS METALS NOBLE GASES 6 138.9 57 La Lanthanum 140.1 58 Ce Cerium 140.9 59 Pr Praseodymium 144.2 60 Nd Neodymium (145) 61 Pm Promethium 150.4 62 Sm Samarium 152.0 63 Eu Europium 157.3 64 Gd Gadolinium 158.9 65 Tb Terbium 162.5 66 Dy Dysprosium 164.9 67 Ho Holmium 167.3 68 Er Erbium 168.9 69 Tm Thulium 173.0 70 Yb Ytterbium 175.0 71 Lu Lutetium 7 (227) 89 Ac Actinium 232.0 90 Th Thorium 231.0 91 Pa Protactinium 238.0 92 U Uranium (237) 93 Np Neptunium (244) 94 Pu Plutonium (243) 95 Am Americium (247) 96 Cm Curium (247) 97 Bk Berkelium (251) 98 Cf Californium (252) 99 Es Einstenium (257) 100 Fm Fermium (258) 101 Md Mendelevium (259) 102 No Nobelium (262) 103 Lr Lawrencium Lanthanoids Actinoids 303 302
Matter and measurement 1 L E A R N I N G S I T UAT I O N You have probably had packaged food or drink on more than one occasion . Have you ever thought about how packaging i s made? Measurements are taken so that the cont ents f it in the packaging and there i s no excess space. A design t eam creat es the shape of the packaging so that many identical ones can be packed together and easi ly transpor t ed . A suitable, cheap mat erial i s al so chosen . Should we throw al l thi s ef for t away? Some containers or the mat erial they are made of can be reused for di f ferent purposes. Thi s makes a good chal lenge! Reduce the production and consumption of packaging CHALLE NGE 8
Take act ion We are moving towards a more sustainable world . In 2015, the UN approved a set of Sustainable Development Goals (SDGs). Their aim is to create a more equal , environmentally friendly society. To reduce the use of packaging, you will learn about the materials available on our planet and how to use them ef ficiently. This will allow us to live better and enable future generations to enjoy natural resources. Target 12.5: "By 2030, substantially reduce waste generation through prevention , reduction , recycling and reuse." Which of these can you measure with the instruments you have access to? With which instruments can you measure them? • Length • Time • Temperature • Weight • Smell • Taste • Hardness • Pressure • Speed • Volume • Surface area • Colour WORK WITH THE IMAGE Look at the instruments in the images. What are they used for? Does either of them have two scales of measurement? Identify it. What is the relationship between the two scales? Find three values on one scale and write down the numbers that they represent on the other scale. L E T ' S G E T S TA R T E D IN THIS UNIT… Matter and its properties Measurement Measuring instruments Indirect measurements Converting units 9
THE SCIENCES OF PHYSICS AND CHEMISTRY Science aims to provide a rational explanation for what occurs. It is divided into branches, such as physics, chemistr y and biology, which study dif ferent types of situations. REVIEW 1 Explain whether these phenomena are physical or chemical changes: a) Dissolving sugar in water. b) Burning wood. c) Grinding food. d) Moulding a piece of clay. e) Melting ice cream. f ) Frying a steak. A C T I V I T I E S Physics explains the properties of water, such as its temperature, density and physical state. When water cools down , it turns into ice. When water heats up, it turns into steam. Ice, steam and water are the same substance in different physical states. Chemistr y studies which elements make up water and how they are held together. When we pass an electric current through water, two gases, hydrogen, H2, and oxygen, O2, appear in the tubes. These substances are different from water, H2O. Examples of physical changes Examples of chemical changes Changes in shape or position Mixtures Combustion Oxidation Hydrogen Oxygen Physics studies the changes in matter that do not affect its nature. After a physical change, substances remain the same. Chemistr y studies the composition of matter and the changes that affect its nature. After a chemical change, substances are transformed into different substances. Physics Chemistr y 10
1 1. Matter and its properties Matter is ever ything that occupies space and has mass. The bench you sit on , the book you read and your body are all matter. Wood , water and air are also matter. When matter forms objects with defined boundaries ( like a bench), it is called a body. When matter has no defined boundaries ( like air), it is called a material system. Some materials can be used to make bodies. For example, wood can be used to make a bench . Other materials cannot be used to make objects with defined boundaries and they must be placed in a container. For example, the air in a ball . 2 Should packaging for food have the same properties as packaging for toys or stickers? Why? 3 What properties could packaging have to make it easier to recycle? Detect air Some material systems, such as air, are difficult to detect. Look at this experiment. 1. Put some water in a glass and mark the water level. 2. Turn a smaller empty glass upside down and place it inside. Hold the glass and when it reaches the bottom, mark the water level. 3. Without taking the glass out of the water, tilt it to release the bubbles. 4. After all the bubbles have been released, mark the water level. 4 How do you know there was air in the glass? 5 Is it possible to know how much air there was? Write the answer in your notebook. 6 Which ones are matter? a) Pencil b) Music c) MP3 file d) Carbon dioxide e) Writing f ) Cat g) Light h) Sand i ) Cotton 7 Classify these terms as bodies or material systems: a) Book b) Phone c) Aluminium d) Juice e) Air f ) Atmosphere g) Bottle of water h) Bird i ) Moon A C T I V I T I E S Conclusions CHALLENGE 11
1. Matter and its properties 1.1. Properties of matter Properties of matter are the aspects of it we can evaluate. These properties can be classified according to dif ferent criteria . Look at the diagram. 8 The text below describes the contents of the glass in the photo: Oil is a yellow liquid that does not dissolve in water. It floats on water because its density (0.9 g/cm3) is lower than that of water (1.0 g/cm3). In the glass there are 50 cm3 of oil and 120 cm3 of water at 20 °C. a) Make a list in your notebook of the properties of matter mentioned. b) Classify each property according to the diagram on this page. A C T I V I T I E S Do they help us to identify the matter? No Yes Their value is given as a number and a unit. For example, its mass is 800 g and temperature is 180 °C. Quantitative properties They are found in all types of matter and they can have any value. For example, its mass, volume or temperature. General properties They depend on the size of the object. For example, its mass or length. Extensive properties They are described in words. For example, its texture is soft and its colour is yellow. Qualitative properties They do not depend on the size. For example, its colour or density. Intensive properties Yes No How do we evaluate them? Do they depend on the size of the matter? PROPERTIES OF MATTER They give each type of matter a characteristic value. It makes it possible to identify it. This value does not depend on the quantity. For example, its density, hardness or conductivity. Characteristic or specific properties 12
It indicates the mass per unit of volume. d m V = The three cylinders have the same mass. Iron and brass have similar densities; aluminium is less dense because it occupies more volume. Density It is the amount of a substance that can be dissolved in 100 g of water. Solubility in water It measures resistance to scratching on a scale of 1 to 10. Talc is the softest material; it can be scratched with a fingernail . Its hardness is 1. Diamond is the hardest; it can scratch any other material . Its hardness is 10. Hardness Metals are good conductors of electricity and heat, while wood and plastic are bad conductors. Electrical and thermal conductivity It is the temperature at which a solid turns into a liquid. At a pressure of 1 atmosphere, ice melts at 0 °C. Melting point It is the temperature at which a liquid boils. At a pressure of 1 atmosphere, water boils at 100 °C. Boiling point 1 Characteristic or specific properties of matter 9 In your notebook, match each of these objects with the property for which it is most commonly used. Copper wire Melting point Steel saucepan Electrical conductivity Cork stopper Solubility in milk Cocoa powder Density Antifreeze liquid Thermal conductivity 10 Graduated cylinder A contains water and B contains alcohol. Which of these properties will allow you to identify the two substances? a) Mass d ) Volume b) Colour e ) Boiling point c) Smell f ) Density A C T I V I T I E S A B 200 g of sugar can be dissolved in 100 g of water. Oil does not dissolve in water. Brass Iron Aluminium Talc Diamond 13
2. Measurement Many properties of matter are quantitative, that is, we can write their value as a number and a unit. 2.1. The International System of Units (SI) To measure a quantity, for example, length , we need a unit. Look at this brother and sister : Using dif ferent units makes it dif ficult to compare values. For this reason , an international organisation , the General Conference on Weights and Measures, established a set of units called the International System of Units (SI). Many countries, including Spain , use it. To give ver y large or ver y small quantities, the SI also established multiples and submultiples of these units. 11 Imagine you are going to design some packaging. What quantities do you need to know about the material you want to package? How can you determine the value of these quantities? 12 Can you design a large package that can contain various individual packages? How would you do this? What are the advantages and disadvantages of large packages compared to small packages? We give the result of the measurement as a number followed by the unit used: length of the batter y = 5.0 cm. The International System of Units (SI) defines the symbols for units, multiples and submultiples, as well as the rules for writing them. The symbol for units is written in lower case unless it refers to the name of a person : m (metre), J ( joule). The symbol for multiples and submultiples is written before the unit: km, cL. Symbols never take the plural "s". Therefore, we write eight kilometres as 8 km, not 8 kms. A quantity is any property of matter that can be measured . It is written with a number (the amount) and a unit. A unit is a known amount of a quantity that we use as a reference to measure that quantity. To measure a quantity, we compare it with a unit to establish how many multiples of that unit it contains. Length of the battery 5.0 cm quantity amount unit His younger sister measures it in steps: it is six steps long. The older brother measures the rug in palms: it is 14 palms long. What is the measurement of the rug? CHALLENGE 14
1 2.2. Mass and length Mass and length are fundamental quantities in the International System of Units. Their SI units are the kilogram (kg ) and the metre (m). However, it is also ver y common to measure mass in grams (g ). Quantity SI unit Symbol Mass Kilogram Kg Length Metre m The table below also shows the multiples and submultiples we will use. Name Symbol Factor Unit (mass) Unit (length) Multiple kilo k × 103 kg km hecto h × 102 hg hm deca da × 10 dag dam Base unit g m Submultiple deci d × 10-1 dg dm centi c × 10-2 cg cm milli m × 10-3 mg mm The factor in the table represents the relationship between the multiple or submultiple and the unit. Obser ve what these factors mean . Powers Powers are a mathematical operation in which a number is multiplied by itself several times. The power 83 is read as "eight to the power of three" and it is represented as: 83 = 8 × 8 × 8 Negative exponent powers are the inverse of positive exponent powers. 8 1 8 1 8 8 8 3 3 − = = ⋅ ⋅ To raise a power to another power, we multiply the exponents: 8 8 8 2 3 2 3 6 ( ) = = ⋅ base exponent times 3 times 3 13 Complete this table in your notebook: Symbol Unit Symbol Unit mg … … decilitre km … … millimetre … centimetre hg … … millimetre dag … 14 Take a milk carton and measure its height, width and length with a ruler. a) Write the result in cm, mm and m. b) Calculate the dimensions of a package containing six milk cartons. Write it in cm, mm and m. 15 A foot is a measurement of length based on the human foot. Using your foot as the unit of measurement, measure the length of the whiteboard and write down the result. a) If you had used this unit of measurement last year, would you have obtained the same result? What if you used it next year? b) Does wearing shoes affect the result? c) Look for information about the distance that is equal to a foot. Has it been the same throughout history? d) Is it appropriate to use the foot as a unit of measurement? Compare it with the metre. A C T I V I T I E S Multiples 101 = 10 102 = 100 103 = 1000 ten hundred thousand 2 zeros 3 zeros 1 zero Submultiples 10-1 = 1 10 = 0.1 10-2 = 1 102 = 1 100 = 0.01 10-3 = 1 103 = 1 1 000 = 0.001 tenth hundredth thousandth 1 zero 2 zeros 3 zeros 15
Mass kg hg dag g dg cg mg Length km hm dam m dm cm mm : 10 : 10 : 10 : 10 : 10 : 10 × 10 × 10 × 10 × 10 × 10 × 10 : 10 : 10 : 10 : 10 : 10 : 10 × 10 × 10 × 10 × 10 × 10 × 10 Converting quantities For measurements of mass and length : 2. Measurement 16 Convert these amounts: a) 25.8 g ® cg b) 0.05 hg ® dg c) 3.5 dag ® kg d) 450 mg ® kg 17 Convert these amounts: a) 8.15 km ® m b) 1.45 dam ® dm c) 0.04 dm ® cm d) 59 mm ® dm 18 Convert these amounts: a) 16 g ® hg b) 0.25 dag ® mg c) 7.5 km ® cm d) 50 dm ® hm 19 Order these amounts from largest to smallest: a) 0.015 kg 2 765 dg 2.54 dag b) 75 cm 0.65 dm 1.25 m c) 0.05 hg 350 dag 3 672 mg A C T I V I T I E S S O LV E D P R O B L E M 1 Write 0.8 km in dm. 1. Identify the initial unit and the final unit. km ® dm 2. To move from one to the other, go towards the end of the submultiples. The exponent of 10 will be positive. 3. Count the number of steps between the two units. This is the exponent of 10. km hm dam m dm 4. Write it in the corresponding unit. 0.8 km = 0.8 × 104 dm = 8 000 dm × 10 × 10 × 10 × 10 4 steps S O LV E D P R O B L E M 2 Write 850 dg in hg. 1. Identify the initial unit and the final unit. dg ® hg 2. To move from one to the other, go towards the end of the multiples. The exponent of 10 will be negative. 3. Count the number of steps between the two units. This is the exponent of 10. hg dag g dg 4. Write it in the corresponding unit. 850 dg = 850 × 10-3 hg = 850 × 1 103 hg = 0.85 hg : 10 : 10 : 10 3 steps To convert an amount into the next highest multiple, we divide it by 10. For example: 20 hg = 2 kg. To convert an amount into the next smallest submultiple, we multiply it by 10. For example: 5 g = 50 dg. 16
2.3. Surface area Surface area is a quantity obtained by multiplying two lengths, which must be expressed in the same unit. For example: 5.40 m × 6.50 m = 35.10 m2 1 S O LV E D P R O B L E M 3 Write 0.5 dam2 in dm2. S O LV E D P R O B L E M 4 Write 85 cm2 in m2. For measurements of surface area : To obtain the next largest multiple, divide it by 100. For example: 500 cm2 = 5 dm2. To obtain the next smallest submultiple, multiply it by 100. For example: 3 m2 = 300 dm2. What do the factors in the table mean? 1. Identify the units. dam2 ® dm2 2. To move from one to the other, go towards the submultiples. The exponent of 100 will be positive. 3. Count the number of steps between the two units. This is the exponent of 100. dam2 m2 dm2 4. Write it in the corresponding unit. 0.5 dam2 = 0.5 × 1002 dm2 = 0.5 · 104 dm2 = 5 000 dm2 × 100 × 100 2 steps 1. Identify the units. cm2 ® m2 2. To move from one to the other, go towards the multiples. The exponent of 100 will be negative. 3. Count the number of steps between the two units. This is the exponent of 100. m2 dm2 cm2 4. Write it in the corresponding unit. 85 cm2 = 85 × 100-2 m2 = 85 × 10-4 m2 = 85 × 1 104 m2 = 0.0085 m2 : 100 2 steps : 100 Multiples 102 = 100 104 = 10 000 106 = 1 000 000 hundred ten thousand million 2 zeros 4 zeros 6 zeros Submultiples 10-2 = 1 102 = 1 100 = 0.01 10-4 = 1 104 = 1 10 000 = 0.0001 10-6 = 1 106 = 1 1 000 000 = 0.00 0001 hundredth ten thousandth millionth 2 zeros 4 zeros 6 zeros 20 Convert these amounts: a) 1.25 m2 ® cm2 b) 0.082 km2 ® dm2 c) 1.007 dam2 ® mm2 d) 500 cm2 ® dm2 21 Take a milk carton and calculate the surface area of each of its sides. What measurements should you take? Write the result in cm2 and m2. 22 A commonly used unit of surface area is the hectare (10 000 m2). How many hectares is a football pitch that is 100 m long and 70 m wide? 23 Order these amounts from largest to smallest: a) 1 432 cm2 347 dam2 0.0005 km2 b) 0.000 564 hm2 657 892 cm2 4.5 m2 A C T I V I T I E S Surface area km2 hm2 dam2 m2 dm2 cm2 mm2 : 100 : 100 : 100 : 100 : 100 : 100 × 100 × 100 × 100 × 100 × 100 × 100 Name Symbol Factor Unit Multiple kilo k × 106 km2 hecto h × 104 hm2 deca da × 102 dam2 Unit base m2 Submultiple deci d × 10-2 dm2 centi c × 10-4 cm2 mili m × 10-6 mm2 17
For measurements of volume: To obtain the next largest multiple, divide it by 1 000. For example: 4 000 dm3 = 4 m3. To obtain the next smallest submultiple, multiply it by 1 000. For example: 2 hm3 = 2 000 dam3. What do the factors in the table mean? Volume km3 hm3 dam3 m3 dm3 cm3 mm3 : 1 000 : 1 000 : 1 000 : 1 000 : 1 000 : 1 000 × 1 000 × 1 000 × 1 000 × 1 000 × 1 000 × 1 000 Multiples 103 = 1 000 106 = 1 000 000 109 = 1 000 000 000 thousand million thousand million 3 zeros 6 zeros 9 zeros Submultiples 10-3 = 1 103 = 0.001 10-6 = 1 106 = 0.000 001 10-9 = 1 109 = 0.000 000 001 thousandth millionth thousand millionth 3 zeros 6 zeros 9 zeros Name Symbol Factor Unit Multiple kilo k × 109 km3 hecto h × 106 hm3 deca da × 103 dam3 Base unit m3 Submultiple deci d × 10-3 dm3 centi c × 10-6 cm3 milli m × 10-9 mm3 S O LV E D P R O B L E M 5 Write 0.5 m3 in mm3. 1. Identify the units. m3 ® mm3 2. To move from one to the other, go towards the submultiples. The exponent of 1 000 will be positive. 3. Count the number of steps between the two units. This is the exponent of 1 000. m3 dm3 cm3 mm3 4. Write it in the corresponding unit. 0.5 m3 = 0.5 × 1 0003 mm3 = 0.5 · 109 mm3 = = 500 000 000 mm3 S O LV E D P R O B L E M 6 Write 850 dam3 in km3. 1. Identify the units. dam3 ® km3 2. To move from one to the other, go towards the multiples. The exponent of 1 000 will be negative. 3. Count the number of steps between the two units. This is the exponent of 1 000. km3 hm3 dam3 4. Write it in the corresponding unit. 850 dam3 = 850 × 1 000-2 km3 = 850 × 10-6 km3 = = 850 × 1 106 km3 = 0.000 85 km3 × 1 000 × 1 000 × 1 000 3 steps : 1 000 : 1 000 2 steps 24 Convert these amounts: a) 73.357 cm3 ® mm3 b) 1.0576 dam3 ® dm3 25 Order these amounts from largest to smallest: 6.42 cm3 0.935 dm3 2 575 mm3 A C T I V I T I E S 2.4. Volume Volume is a quantity obtained by multiplying three lengths, which must be expressed in the same unit. For example: 5.40 m × 6.50 m × 3.0 m = 105.3 m3 2. Measurement 18
The relationship between units of volume and units of capacity We usually refer to the volume of a body and the capacity of a container. These refer to the same quantity. Therefore, we can relate units of volume and units of capacity. Imagine in a drinking glass the volume occupied by the glass material is 60 mL. This means that if we put it in a graduated container with water, the water level will rise by 60 mL. If the capacity of the drinking glass is 250 mL, we can pour up to 250 mL of liquid into it. If we pour in 100 mL, the volume of the liquid in the glass will be 100 mL, but the capacity of the glass will still be 250 mL. How many L are in 1 m3? How many L is 1 dm3 equal to? How many mL is 1 cm3 equal to? 1 m3 is a cube with side 1 m. Divide each m into 10 dm. Cut along all the lines. You will have 1 000 cubes of side 1 dm. 1 dm3 is a cube with side 1 dm. Divide each dm into 10 cm. Cut along all the lines. You will have 1 000 cubes of side 1 cm. 1 cm3 is a cube with side 1 cm. 1 cm3 is a thousandth of 1 dm3. Therefore, it is equal to 1 mL (millilitre). 1 m3 = 1 000 dm3 = 1 kL = 1 000 L 1 dm3 = 1 000 cm3 = 1 L 1 cm3 = 1 mL = 0.001 L 1 m3 1 dm3 1 cm 1 cm3 1 cm S O LV E D P R O B L E M 7 Write 0.5 daL in mL. 1. Identify the initial unit and the final unit. daL ® mL 2. To move from one to the other, go towards the end of the submultiples. The exponent of 10 will be positive. 3. Count the number of steps between the two units. This is the exponent of 10. daL L dL cL mL 4. Write it in the corresponding unit. 0.5 daL = 0.5 × 104 mL = 5 000 mL × 10 × 10 × 10 × 10 4 steps 26 Take a carton that states that it contains 1 L of milk or juice. a) Use a ruler to measure the length, width and height of the carton and then calculate the volume. b) Explain whether the carton can contain 1 L of liquid. 27 Convert these amounts: a) An Olympic-size swimming pool contains 2.5 million litres of water. Write this in m3. b) Soft drink cans have a volume of 33 cL. Write this in cm3. A C T I V I T I E S 1 100 mL 250 mL Capacity kL hL daL L dL cL mL : 10 : 10 : 10 : 10 : 10 : 10 × 10 × 10 × 10 × 10 × 10 × 10 19
We use a ruler to measure the length of a table, a stopwatch to measure the time it takes for a ball to fall, and a thermometer to measure the temperature of water. A different instrument is used for each quantity. 3.1. Measuring mass The mass of a body is the amount of matter it contains. It is measured with scales. Mass and weight are two dif ferent quantities. Weight is the force with which a body is attracted by the celestial body where it is located . The weight of a body on the Earth is dif ferent to its weight on the Moon , although its mass does not change. 3. Measuring instruments 28 What measuring instruments do you use when you buy loose fruit, rather than packaged fruit? 29 How do you know how much water or soft drink is in a container? With the scales at rest, place the object on one of the pans. Add weights to the other pan . Press the lever and when the needle points to zero, the mass of the body is equal to the sum of the mass of the weights. Precision scales or pan balance Can we recycle disposable drink cups? Disposable cups for cof fee or other drinks are containers made of cardboard . They are also coated with a thin layer of plastic so they can hold liquids. As most of the cup is made of cardboard , they can be recycled . Used paper and cardboard cups should be recycled in the paper bin. Turn on the scales and wait for zero to appear. Place the empty container on top and press the tare button . The display will read 0 g even though the container is on the scales. Without touching the scales, remove the container and put the substance you want to weigh inside it. Put it back on the scales and read its mass. Electronic scales 30 A pan balance is in equilibrium when we place a tangerine on one pan and these weights on the other. What is the mass of the tangerine? 2 g 1 g 31 If you place this object on one of the pans of a pan balance, which weights do you have to put on the other pan for it to be in equilibrium? A C T I V I T I E S CHALLENGE T R U E OR FALSE ? 20
3.2. Measuring volume The volume of a body is a measurement of the space it occupies. For objects that have a regular shape, such as a cube, sphere, prism or cylinder, the volume can be calculated by using formulas, measuring some lengths and making calculations. For liquids or objects with an irregular shape, we use measuring instruments such as a graduated cylinder, a burette or a pipette. 32 What volume of liquid do these graduated cylinders contain? The measurements are all in mL. a) b) c) 33 In your notebook, do a magnified drawing to show that the level of liquid in each graduated cylinder is: a) 5.2 mL b) 27 mL c) 180 mL A C T I V I T I E S 1 Eye level Lower part of the meniscus When we pour a liquid into a narrow tube, it sticks to the sides, causing the outer part to form a cur ve called a meniscus. Graduated cylinders are designed to indicate the measurement at the bottom of the meniscus. To avoid errors when taking measurements, the graduated cylinder must be horizontal and our eyes must be level with the height of the measurement, that is, the bottom of the meniscus. Some f lasks, Erlenmeyer f lasks and beakers only give approximate measurements. Flask Erlenmeyer flask Beaker 25 mL graduated cylinder. It allows 0.5 mL to be measured. 50 mL graduated cylinder. It allows 1 mL to be measured. 250 mL graduated cylinder. It allows 5 mL to be measured. Burette Pipette Instruments for measuring volume precisely. Their graduation depends on their size and the manufacturer. 21
To measure the mass of a body, we use scales that directly indicate its value. But this cannot be done with other quantities, such as surface area or density. 4. Indirect measurements 34 Imagine you want to know the amount of aluminium used to make a can. However, you only have bathroom scales, which are not very accurate, and a lot of empty cans. Can you think of a way to calculate the mass of a single can? 35 How can you find out the density of the aluminium that a can is made of? Indirect measurements are those obtained by performing a mathematical operation on other direct measurements. Measure the volume of a drop of water Stand Burette Tap Beaker Calculate the volume of a drop of water Number of drops: N Volume of water: 5 mL Volume of 1 drop = 5 mL N 1. Pour water into the burette to above the 0 mL level. 2. Open the tap so the water slowly drips out. You should be able to count the drops. 3. When the water level in the burette reaches 0 mL, start counting the drops. Do this until the water level is 5 mL. Steps Material Graduated burette Beaker Stand Water CHALLENGE 22
4.1. Measuring surface area If it is a regular body, we can measure its sides and angles and use a mathematical formula . If it is an irregular body, we can use a graph paper template or weigh it. 1 Measure surface area by weight Calculate the surface area Measured surface area: SM = 1 dm2 MM = 20.8 g Surface area you need to find: SF = 8 3 1 20 8 2 . . g g dm × ® SF = 0.39 dm2 1. Cut out the irregular surface area. 1 dm2 1 dm2 3. Weigh the measured surface area, SM. Its mass is MM. 4. Weigh the irregular surface area. The surface area you need to find is SF. 36 Sometimes, you need to be inventive to measure a quantity indirectly. Use the pictures to help you design a method that allows you to: a) Measure the thickness of a sheet of paper. b) Find out how many screws are in a drawer without counting them. 37 The owner of a fabric shop wants to know how many square metres of fabric are left on a roll that is 2 m wide. Can you think of a way of measuring this without having to unroll all the fabric? Clue: you can use scales. A C T I V I T I E S 2. Cut out a measured surface area from the same material (for example, a square with side 1 dm). 23
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