877306 _ 0001-0005.qxd 15/2/08 18:25 Página 877306 _ 0001-0005.qxd 15/2/08 18:25 Página Contents PAGE About this book Learning to learn Getting closer to the stars! The Universe Planet Earth 18 Learning to learn All creatures great and small 28 Living things 30 Invertebrates 42 Vertebrates 52 The plant and fungi kingdoms 62 The simplest living things 74 Learning to learn Rock stars and instruments 84 The Earth’s atmosphere 86 The hydrosphere 96 10 Minerals 106 11 Rocks 116 Learning to learn It’s elementary! 128 12 13 14 Matter and its properties 130 Everything is matter 140 Atoms and elements 150 Vocabulary 160 Key language 164 877306 _ 0001-0005.qxd 15/2/08 18:25 Learning to learn Página A B ABOUT THIS BOOK • Look at these illustrations Match them to the units on the opposite page Then look at the book, and check your answers Unit C D Unit F E Unit G Unit I Unit Unit Unit K Unit M Unit Unit H J L Unit Unit N Unit Unit 877306 _ 0001-0005.qxd 15/2/08 18:25 Página YOU ALREADY KNOW A LOT! Work with a partner Try to answer these questions THE UNIVERSE How many planets in our galaxy can you name? THE EARTH How long does it take the Earth to rotate on its axis? And how long does it take to orbit the Sun? INVERTEBRATES Can you name six invertebrates? PLANTS Plants are autotrophic: they make their own food What is the name of the process by which plants this? THE EARTH’S ATMOSPHERE Can you name three meteorological instruments? What does each one measure? THE HYDROSPHERE Water is present on Earth in gaseous, liquid and solid form Name four different places where you can find water in nature 877306 _ 0001-0005.qxd 15/2/08 18:25 Página MINERALS Quartz is a mineral Can you name any other minerals? Can you say what each is used for? MATTER AND ITS PROPERTIES Oil floats on water Which has the greatest density, oil or water? THE STATES OF MATTER Look at these three drawings They represent a solid, a liquid and a gas Can you match each drawing to its state? UNIT The Universe What you remember? • What are the points of light in this photo? • What is the difference between … – a star and a planet? – a moon and a comet? STUDY A UNIT Look at page 8, the first page of Unit • What is the title of the unit? • How many different sections are there on the page? What are they about? Key language In this unit, you will … • Learn about the characteristics of the Universe • Calculate astronomical sizes and distances • Analyse the components of the Universe • Compare sizes: the Sun and the planets • Create a constellation poster Describing Planets are spherical bodies which orbit the Sun Asteroids are rocky objects which are irregular in shape Comparing Dwarf planets are smaller than planets The Earth is larger than Mercury Giving instructions Study the constellations Research more about them on the Internet • What you think you will learn about in Unit 1? Now look at the rest of Unit Content objectives • How many sections are there in this unit? • What can you find on page 17? How is this useful? • What are most of the illustrations about? Symbols • Some words are in bold Why is this? • The text is recorded on the CD • How many activities are there in this unit? • The information you need is available on the CD • What will you in the Hands on section, page 15? 877306 _ 0006-0007.qxd 15/2/08 18:16 Página Getting closer to the stars! Telescopes are used to see objects that are too far away to be seen with the naked eye They also provide a closer view of distant things Astronomers use large telescopes to study the planets, stars, and other objects in space Without telescopes, we wouldn’t know much about celestial bodies! Lenses or mirrors? Telescopes with lenses are called refracting telescopes Lenses bend the light The largest telescopes use mirrors instead of lenses Telescopes with mirrors are called reflecting telescopes Mirrors reflect light Look through this end The things you observe seem closer! eyepiece: lens to view the image focus adjustment: move this to make the image clearer Some telescopes are small enough to be carried in one hand Others can be huge, bowl-shaped radio telescopes, more than 300 metres in diameter This is longer than three football pitches! 877306 _ 0006-0007.qxd 15/2/08 18:16 Página Optical telescopes consist of a long tube, with one end narrower than the other They can “perceive” light, just like eyes tube OOPS! Wrong end! objective lens: the lens closest to the object being viewed How does a telescope work? Objects reflect light This light enters our eyes, and we see the object Optical telescopes have an objective lens: a curved piece of glass at the wide end This lens bends the light from the object so that it forms an image – a picture of the object – inside the telescope The light from this image then goes through the eyepiece, at the narrow end of the telescope The eyepiece bends the light back again, so the object looks big tripod: three-legged stand to support the telescope The Gran Telescopio Canarias (GTC), also called GranTeCan, is a 10.4 m reflecting telescope, located on a volcanic peak (2,400 metres) on the island of La Palma, Spain It took seven years to construct! Activities Galileo Galilei invented the telescope Why was this such an important discovery? What did astronomers know about the stars before then? Research Have you heard of the Hubble telescope? When was it built? Where is it? What pictures does it take? 877306 _ 0008-0017.qxd 20/2/08 12:22 Página UNIT The Universe What you remember? • What are the points of light in this photo? • What is the difference between … – a star and a planet? – a moon and a comet? Content objectives Key language In this unit, you will … Describing • Learn about the characteristics of the Universe Planets are spherical bodies which orbit the Sun Asteroids are rocky objects which are irregular in shape • Calculate astronomical sizes and distances Comparing • Analyse the components of the Universe Dwarf planets are smaller than planets The Earth is larger than Mercury • Compare sizes: the Sun and the planets • Create a constellation poster Giving instructions Study the constellations Research more about them on the Internet 877306 _ 0008-0017.qxd 15/2/08 19:04 Página What is the Universe like? Scientists developed two different theories to explain what the Universe was like Activities Find ten words in the word search M P I L A N E T S G R L A A S A L U A T S R P T K N E • Geocentric theory nd century BC: Ptolomy proposed that the Earth was the centre of the Universe That is, the Sun, Moon and planets orbited the Earth • Heliocentric theory In 1542, Nicolas Copernicus proposed that the Sun was at the centre of the Universe In 1610, Galileo Galilei invented the telescope, and proved the Heliocentric theory: the planets and stars revolve around the Sun L T T A E Y S E N A H C L W O H B R X E L A T M S U N Y I Y M O O N L G T K E S W C P A E Imagine an alien friend from another galaxy wants to write to you Write your galactic address What makes up the Universe? The Universe is all the matter, energy and space that exists The Universe is made up of galaxies which contain stars Stars can have planetary systems made up of planets and satellites Galaxies are separated by vast spaces Galaxies are a vast collection of stars, dust and gases, held together by the gravitational attraction between the components They appear in groups called galaxy clusters Scientists think the vast spaces between the galaxies are empty Our galaxy, the Milky Way, belongs to the Local Group galaxy cluster Stars form when clouds of gases are pulled together by gravitational forces They are so hot inside that they emit heat and light A galaxy can have up to five hundred thousand million stars An enormous cloud of gas and dust, a nebula, surrounds the stars Planets are bodies which orbit some stars They not emit light; they receive light from the star They make up planetary systems Our planetary system is the Solar System It is made up of eight planets and one star, the Sun, as well as moons, comets and asteroids The Solar System is located on a spiral arm of the Milky Way Natural satellites orbit some planets The Earth’s natural satellite is the Moon 877306 _ 0008-0017.qxd 15/2/08 19:04 Página 10 How big is the Universe? The Earth seems huge, but, in reality, it is small compared to the Sun The Sun is only one of the millions of stars in the Milky Way To imagine the size of the Universe, use these comparisons with everyday objects Activities Express the distance of Mercury, Mars and Pluto from the Sun in kilometres • Imagine the Sun is the size of a pea • The closest star is another pea, five hundred and forty kilometres away from the first pea • The Earth is like a particle of dust situated two metres away from the first pea • The Milky Way contains one hundred thousand million peas which form a circle with a radius of seven million kilometres What units of measurement astronomers use? Mars Mercury Pluto Research the term light-year Why is it used in astronomy? Did you know that ? • Astronomical unit (AU) This is the distance from the Earth to the Sun Approximately 150 million kilometres Compare the distance of these planets from the Sun: – Mercury: 0.4 AU – Mars: 1.5 AU – Pluto: 39.4 AU • Light-year This is the distance light travels in one year Light travels 300,000 km in one second or 9.5 trillion km in one year 10 Source of light Time to reach the Earth the Sun mins 20 sec Centauri, the nearest star light-years Betelgeuse 500 light-years The radius of the Sun is 109 times greater than the radius of the Earth 877306 _ 0150-0159.qxd 15/2/08 19:35 Página 154 What is a chemical formula? Oxygen molecule (O2) Each element has its own chemical symbol: oxygen is O, calcium is Ca To describe molecules, a chemical formula is used A chemical formula consists of chemical symbols and numbers to indicate how many atoms of each element make up a molecule two oxygen atoms For example, the formula for carbon monoxide is CO This means that each molecule of carbon monoxide consists of one carbon atom joined to one oxygen atom • Simple substances The formula indicates the molecule of the substance For example, O2 is the formula for the substance with molecules made up of two oxygen atoms joined together F O2 number of atoms F symbol for the element • Compound substances The formula indicates which elements make up the molecule For example, a water molecule, H2O, consists of one atom of oxygen joined to two atoms of hydrogen F F H2O number of atoms oxygen atom F F symbols for each elements • Crystals Some elements form simple crystals In this case, the chemical formula is the same as for the chemical symbol for the element For example, carbon crystals: C hydrogen atoms Water molecule (H2O) • Compound crystals The chemical formula indicates the elements and their proportions within the crystal F F NaCl chlorine atom proportion of each F F symbols for elements sodium atom • Some chemical formulae are more complicated For example, the formula for sodium sulphate is Na2SO4 It indicates that sodium sulphate consists of two sodium atoms, one sulphur atom and four oxygen atoms Sodium chloride molecule (Na Cl) Activities 11 Copy the table and complete Name 154 Chemical formula iron oxide Fe2 O3 silver oxide Ag2 O aluminum oxide Al2 O3 Atoms: name and number 12 Sucrose is the chemical name for sugar Its formula is C12H22O11 a How many elements make up this substance? b What is the name of each element? c How many atoms of each element are there in sucrose? 877306 _ 0150-0159.qxd 15/2/08 19:35 Página 155 Which elements can be found in nature? There are more than 110 elements in the Periodic Table, 92 are found in nature All the others are man-made Universe hydrogen 83.9 % Hydrogen and helium are the most abundant elements in the Universe The stars are made up mainly of these two elements Hydrogen (H2) is a gas It makes up 83% of the Universe It is found in the atmosphere, water, rocks… Helium (He) is a noble gas It makes up 15.9% of matter in the Universe, but there is very little on Earth other elements 0.2 % helium 15.9 % Living things hydrogen 63 % others 0.6 % Carbon, hydrogen, oxygen and nitrogen form 95% of all living things Atoms of carbon combine with many other atoms to form a wide variety of molecules in living things Some elements can be found both in living beings, in water and on the Earth’s crust However, they form different compounds oxygen 25.5 % nitrogen 1.4 % Nitrogen (N2) is a gas formed by molecules It is the most abundant gas in the Earth’s atmosphere It is a basic compound of proteins There is nitrogen in the soil oxygen 47 % Oxygen (O2) is a gas formed by molecules It is the most abundant element on Earth It is found in the atmosphere in water, rocks and organic substances carbon 9.5 % Earth’s crust silicon 28 % aluminium 7.9 % Carbon (C) is the basis of all organic compounds in living things It is found on the Earth’s crust as coal, graphite others 1.69 % iron 4.5 % calcium 3.5 % sodium 2.5 % potassium 2.5 % carbon 0.19 % hydrogen 0.22 % magnesium 2.2 % Did you know that ? Living things are made up of about twenty elements Activities 13 Compare the pie charts a Which is the most homogeneous? In which is there more diversity? b Ask questions about the charts: for example, Where is there more hydrogen? In the Universe or the Earth’s crust? Is there any silicon in living things? 14 Carbon is not the most abundant element in living things Which element is? 155 877306 _ 0150-0159.qxd 15/2/08 19:35 Página 156 Why are elements important? In the Earth´s crust The most abundant elements which form the rocks and minerals of the Earth’s crust are silicon, aluminium, iron, magnesium and calcium • Silicon (Si) is a solid, non-metal substance It is generally found as a compound: the most common is quartz It combines with oxygen to form silicates • Aluminium (Al) is a soft, light metal It is only found as a compound and is obtained from bauxite Aluminium alloys are used to make aeroplanes, ships, etc • Iron (Fe) is a grey metal It is generally found as a compound It combines with oxygen to form hematite and magnetite Iron is present in your blood Magnesium is used in the composition of fireworks Did you know that ? Pure silicon is used to make microchips for computers • Magnesium (Mg) a silvery metal It is found in minerals such as olivine It burns very easily with a very bright, white flame • Calcium (Ca) is a greyish white metal, found only in compounds Calcium carbonate, (CaCO3), is found in seashells and egg shells In sea water The most abundant elements in sea water are chlorine, sodium and potassium • Chlorine (Cl) is a yellowish green gas at room temperature It combines with metals to form salts Chlorine is used to disinfect water in swimming pools • Sodium (Na) is a soft, shiny metal It is only found in compounds It reacts easily with the oxygen in the air Sodium chloride (NaCl) is common salt • Potassium (K) is a soft, shiny metal It is only found in compounds like potassium chloride (KCl) Sodium and potassium are also present in living things They help muscle contraction and the functions of the nervous system 156 Water is disinfected with chlorine Activities 15 Which element can you find in: fireworks, sea shells, aeroplanes, and blood? 16 Classify the elements on this page in a table Metal Non metal 17 Describe an element Your partner guesses which one It is a soft, shiny metal It is found in common salt 877306 _ 0150-0159.qxd 20/2/08 13:02 Página 157 Hands on Writing a fact file: Elements Research an element from the Periodic Table Then, write up your fact file Follow this outline to help you Chemical composition Choose an element What is its atomic symbol? Draw the atom What is its chemical formula? Some interesting elements: copper, iron, phosphorus, sulphur, fluorine, iodine Why it is important Is it important in living things, or in the Earth’s crust? Give some facts and examples Description Write a physical description of the substance Is it solid, liquid or gas? Is it a metal or a non-metal? Some important uses What is this element or its compounds used for? What other forms does it have? Where it is found in nature Is it found as a simple substance or a compound substance? Is it abundant or rare? Calcium Fact File Calcium, Ca has an atomic number of 20 Description Calcium atom Calcium is a soft, grey metal Where it is found in nature Calcium is not found as an element in nature It is usually found in rocks like limestone or gypsum Why it is important Calcium is the fifth most abundant element in the Earth’s crust It is also essential for living things It is the most common mineral in the human body 99 % of this is found in bones and teeth Calcium carbonate (CaCO3) is the main component of seashells, egg shells and snail shells Some important uses It is used as an antacid for stomach pains 157 877306 _ 0150-0159.qxd 15/2/08 19:35 Página 158 Activities 25 Study the diagrams Different atoms are shown in different colours 18 Copy and label this atom: nucleus protons neutrons electrons 19 Each of these formulas represents a gaseous substance: (CO) carbon monoxide, (NO) nitrogen oxide, (C4H10) butane A B C D Explain the meaning of each formula 20 Write the formula for a substance which contains two atoms of hydrogen, one atom of sulphur, and four atoms of oxygen 21 Carbon monoxide is a gas: CO Lead is a solid, heavy metal Could these substances be found as molecules or as crystals? 22 What is the difference between an atom and a molecule? a Which drawings correspond to elements? b Which drawings correspond to compounds? Explain your answers c Can you see any molecules? How many atoms does each have? 26 Copy and complete the table Element 23 Use the Periodic Table to make a list of the elements that are most abundant in: a The Universe b The Earth’s crust 24 Copy and complete the summary for each element Compound Copper (Cu) Sulphur dioxide (SO2) Sulphuric acid (H2SO4) Helium (He) Elements in nature Nitrogen (N2) The Earth’s crust In sea water 27 Copy and complete the table Silicon compound / formula Chlorine water (H20) Si sodium hydroxide (NaOH) non-metal sodium sulphate (Na2SO4) It is in quartz It forms silicates calcium carbonate (CaCO3) 158 elements / number of atoms hydrogen: oxygen: 877306 _ 0150-0159.qxd 15/2/08 19:35 Página 159 ATOMS AND ELEMENTS What should you know? Atoms and elements Atoms are the smallest particles of a chemical element They are made up of a nucleus with protons and neutrons, and electrons which orbit the nucleus • Matter is made up of atoms • Elements are formed by equal atoms • Compounds consist of two or more different atoms There are more than one hundred different elements They are classified in the Periodic Table of Elements Substances and formulas Atoms form different types of substances: • Monoatomic: the noble gases • Molecules: the union of two or more atoms – Simple molecules: formed by identical atoms: gases (O2, N2, H2) – Compound molecules: formed by different atoms: compounds in gas or liquid form (H2O, CO2) • Crystals: many atoms joined together in an organised structure – Simple crystals: formed by identical atoms Example: metals – Compound crystals: formed by different atoms Example: solid substances like sodium chloride (NaCl) Elements in nature • Hydrogen A gas formed by molecules (H2) It is the most abundant gas in the Universe • Helium A gas formed by atoms (He) It is the second most abundant gas in the Universe • Nitrogen A gas formed by molecules (N2) It is the most abundant gas in the Earth’s atmosphere • Oxygen A gas formed by molecules (O2) It is the most abundant element on Earth, and the second most abundant in the atmosphere • Carbon is the basis of organic compounds • Silicon is only found as a compound in nature It is the main component of silicates • Aluminium, iron, magnesium and calcium are metals which are abundant in minerals and rocks • Chlorine, magnesium, sodium and potassium dissolve in water They make up the ‘salt’ in sea water 14 Universe Living things Earth’s crust Projects for living things Why? • Why we use fertilizers with nitrogen? • Where does nitrogen in the soil come from? • Can plants live in soil without nitrogen? WEB TASK: Research the world of nanotechnology INVESTIGATE: Nitrogen in soil is very important 159 877306 _ 0160-0163.qxd 18/2/08 09:14 Página 160 Vocabulary The Universe asteroids rocky bodies which orbit the stars astronomical unit the distance from the Earth to the Sun: approximately 150 million kilometres galaxies a vast collection of stars, dust and gases, held together by gravitational attraction geocentric theory proposed that the Earth was the centre of the Universe heliocentric theory proposed that the Sun was at the centre of the Universe light-year the distance light travels in one year: about 9.5 trillion km Milky Way the galaxy where our Solar System is orbit a curved path which a celestial body follows in its revolution around another celestial body Planet Earth atmosphere the layer of gases which envelops the Earth Nitrogen and oxygen are the most abundant biosphere the part of the Earth’s surface, sea and air that is inhabited by living things core the centre of the Earth, below the mantle Its temperature is over 4,000°C crust the outer layer of the Earth’s surface It is divided into continental crust and oceanic crust equinox the time of the year when day and night are exactly the same length geosphere the solid part of the Earth which includes the lithosphere, the mantle and the core hydrosphere all the water on Earth lithosphere the upper 100 km of the geosphere It is is made up of the crust and the upper mantle lunar eclipse when the Moon passes behind the Earth, so the Earth prevents sunlight from reaching the Moon mantle the middle layer of the Earth, below the crust It is made up of rock The temperature is from 1,000 to 4,000ºC, so some areas are melted rock revolution the elliptical path taken by one body around another The Earth revolves around the Sun rotation the Earth rotates on its axis The axis is tilted 23.5 degrees This rotation creates day and night 160 solar eclipse when the Moon passes between the Sun and the Earth, and blocks off the sunlight water cycle the movement of water around, over, and through the Earth: evaporation, condensation, precipitation, surface runoff and infiltration Living things autotrophs living things which produce the organic substances they need from inorganic substances Plants, algae and some bacteria are autotrophs cell membrane the outer covering of a cell The cell membrane keeps the cell together and controls what passes in and out of it chloroplasts organelles with a green pigment, chlorophyll, which absorbs the Sun’s energy to elaborate organic matter during photosynthesis cytoplasm the inside of a cell where many of the chemical reactions take place eukaryotic cells cells which have a nucleus, separated from the cytoplasm by the nuclear membrane heterotrophs living things which obtain nutrition from organic matter which is already elaborated Animals, fungi, and all protozoa are heterotrophs inorganic substances things which contain no carbon They are present in living things and non-living things: water and mineral salts organelles small structures in the cytoplasm responsible for respiration, making and storing nutrients, etc organic substances substances exclusive to living things Carbon is the principal element Organic substances include: glucides, lipids, proteins and nucleic acids nutrition all the processes which enable living things to obtain the energy and matter they need to live photosynthesis the process through which plants obtain nutrition prokaryotic cells cells with no nucleus or nuclear membrane Genetic material is dispersed throughout the cytoplasm They are simpler than eukaryotic cells species the first level of classification for living things A group of living things which are physically similar They reproduce and usually have fertile descendants 877306 _ 0160-0163.qxd 18/2/08 09:14 Página 161 Invertebrates annelids invertebrates with soft, cylindrical bodies divided into segments, with organs in each segment Most breathe through gills arthropods the largest and most varied group of living things: more than one million species They live in sea water, fresh water and on land cephalopods a group of molluscs They have tentacles, but no shell For example: squid, cuttlefish and octopus cnidaria jellyfish, corals and sea anemones They have a soft body, with only one opening and a mouth surrounded by tentacles crustaceans a group of arthropods with 10 legs, with usually an aquatic habitat For example: lobster or crab echinoderms invertebrate animals which live on the sea bed For example, sea urchins, starfish and sea cucumbers gastropods a group of molluscs Gastropods have a spiral-shaped shell with a single valve For example, snails, sea snails and slugs Slugs have no shell poikilotherms cold-blooded animals They cannot regulate their body temperature, so are warm or cold depending on the environment reptiles vertebrate animals with bodies covered with hard scales They are poikilothermal and most of them are oviparous and carnivorous viviparous animals that give birth to live young Development starts in the mother’s body The babies feed on the mother’s milk The plant and fungi kingdoms angiosperm flowering plants which have seeds inside a real fruit dispersal a stage of plant reproduction The ripe fruit falls off the plant or releases the seeds ferns small non-flowering plants Ferns are vascular They have roots, stems, and leaves called fronds molluscs a group of invertebrate animals with a soft body divided into head, body mass and foot For example, squid, mussels, oysters, slugs and snails fertilisation a stage of plant reproduction Pollen reaches the stigma, penetrates it, and fertilises the ovules inside the ovary myriapods a group of arthropods with worm-like bodies and many legs They are terrestrial For example, centipede and scolopendra fungi have eukaryotic cells and are heterotrophic Fungi are made up of hyphae, which group together to form the mycelium oviparous animals that lay eggs Eggs are laid by the female and develop outside the body germination the last stage of plant reproduction Seeds germinate producing a tiny shoot and root platyhelminths invertebrates with long, flat, soft bodies They have neither legs nor respiratory or digestive systems Many are parasites polyp cnidaria bodies shaped like a tube with the opening at the top For example, corals and sea anemones porifera invertebrate animals without organs Sponges belong to this group Vertebrates amphibians vertebrate animals Their skin is moist and has no covering They have four legs and are poikilothermal They undergo metamorphosis homeotherms warm-blooded animals: capable of keeping their body temperature constant gymnosperm one kind of flowering plant They have seeds inside a false fruit, like a pinecone mosses small, non-flowering plants They are nonvascular They have no true roots, stems or leaves pollination the first stage of plant reproduction Wind and insects transport pollen from one flower to another stomata microscopic pores on the underside of a leaf transpiration process by which excess water is expelled through leaf stomata in the form of water vapour vascular plants with conductor vessels to distribute water and nutrients yeasts unicellular fungi Some types are used to make bread, wine, beer, etc The simplest living things mammals a group of vertebrate animals Their bodies are covered with hair or fur They are homeothermal and have mammary glands algae unicellular or multicellular autotrophs They live in salt and fresh water ovoviviparous animals that are born from an egg The egg develops inside the female bacteria microscopic, prokaryotic organisms They belong to the Monera kingdom 161 877306 _ 0160-0163.qxd ciliates 18/2/08 09:14 Página 162 a group of protozoa with hair-like organs flagellates one of the groups of protozoa They move with a flagellum (tail) protoctist unicellular and multicellular living things They are eukaryotes and have no tissues The Protoctist kingdom includes protozoa and algae The hydrosphere condensation the process in which water vapour changes to liquid currents movement of large bodies of water by prevailing winds protozoa unicellular and heterotrophic living things Some are parasites, and cause illnesses evaporation the process of the water cycle in which liquid water changes to a gas (water vapour) rhizopods protozoa with pseudopods (projections of the cell cytoplasm) evapotranspiration when water evaporates into the atmosphere from the leaves and stems of plants saprophytes organisms which live on dead or decomposing matter They transform organic substances into inorganic substances groundwater sporozoa surface runoff when the movement of surface water across the land forms rivers and streams a group of protozoa that cannot move vaccines contain dead or weakened microorganisms from a specific illness They teach the body how to fight an illness The Earth’s atmosphere acid rain rain with dissolved pollutants such as sulphur dioxide and nitrogen oxide climate describes the characteristic pattern of weather in an area, over a long period of time global warming in the last century, the atmosphere has warmed between 0.5 and 0.9ºC on average greenhouse effect a natural phenomenon, essential for keeping the temperatures on Earth suitable for life CO2 in the atmosphere acts like the glass walls of a greenhouse It traps the heat and prevents it from returning into space water located beneath the ground infiltration surface water penetrates into the ground This occurs more easily if the ground is porous tides the rise and fall of water levels due to gravitational attraction of the Moon and the Sun waves occur on the surface of water, caused by the wind Wave action causes cliff erosion and creates beaches 10 Minerals hardness measures how a mineral reacts to being scratched impurities small amounts of other substances found in minerals These can change some mineral properties lustre refers to the way minerals reflect light It can be metallic, or non-metalic mixtures are made up of different substances of varying sizes, shapes and colours ionosphere the highest and thickest layer of the atmosphere Mohs Scale of Hardness classifies minerals by hardness One is soft Ten is the hardest mesosphere a layer of the atmosphere about 40 km thick It contains clouds of ice and dust non-silicates minerals which contain no silicon: native elements, oxides, sulphides, carbonates and halides meteorology the study of different atmospheric variables to make weather predictions ozone (O3) a gas which exists throughout the atmosphere, mainly concentrated in the stratosphere It makes up the ozone layer stratosphere a layer of the atmosphere about 30 km thick There is an increase in temperature from –70ºC at its lower limit, to 0ºC at its higher limit silicates the most abundant minerals on Earth They are made up of silicon and oxygen Some common silicates are quartz and feldspar streak the colour of the powder left when minerals are scratched 11 Rocks troposphere a very thin layer which represents 80% of the total mass of the atmosphere Aeroplanes fly at this level It is where the greenhouse effect is produced cementation the process by which sedimentary rock is formed from sediments glued together weather describes the state of atmospheric conditions at a certain place, over a short period of time compaction the weight of layers of sediments which reduces the spaces between the fragments and squeezes out the water As a result, salt crystals are formed 162 877306 _ 0160-0163.qxd 18/2/08 09:14 Página 163 erosion fragments of rocks are picked up and transported by running water, glaciers, or wind igneous rocks rocks formed from cooled magma metamorphic rocks rocks formed from other rocks by the effects of heat or pressure metamorphism a slow process in which temperature and pressure change parent rock into metamorphic rock organic sedimentary rocks made up of organic material, fossils There are two kinds: oil and coal plutonic (intrusive) rocks rocks formed as magma cools slowly under the ground over thousands of years rock cycle the processes which form, change and recycle rocks over millions of years sedimentary rocks rocks formed by the accumulation and compaction of sediment, for example, clay, sand or rock fragments volcanic (extrusive) rocks rocks formed as lava cools rapidly on the Earth’s surface weathering atmospheric phenomena (changes in temperature, rain, etc.), or the activities of plants and animals which break up rocks 12 Matter and its properties base units used to measure length, mass, time, etc capacity the amount of liquid a container can hold when it is full Capacity is measured in litres (L) degrees Celsius a scale used to measure temperature 0ºC equals 273.15K or 32ºF density the relationship between the mass and the volume of a body Measured in kg/m3 or g/cm3 derived units obtained from a combination of the base units They are used to measure surface area, volume, speed, density, etc International System of Units (SI) a system which defines the base and derived units required to measure the properties of matter kelvin one of the scales of the International System of Units that is used to measure temperature K equals –273.15ºC and –459.67ºF mass the amount of matter in a body Mass is measured in kilograms (kg) matter all objects that take up space, and have mass Everything around us is made of matter surface area the extension of a body in two dimensions, measured in square metres (m2) volume the amount of space matter occupies Volume is measured in cubic metres (m3) 13 Everything is matter chemical compound a substance containing two or more elements joined up compressibility a property which measures the difficulty of matter to be compressed fusion the process by which a solid changes into a liquid heterogeneous a mixture of substances where more than one part is distinguishable homogeneous a substance which is uniform in structure and composition recycle to transform used materials into new materials regressive sublimation the process by which a gas changes directly into a solid solidification the process by which a liquid is cooled and changes to a solid solute in a mixture, the dissolved substance solution any homogeneous mixture solvent in a mixture, the part where the substance is dissolved sublimation the process by which a solid changes into a gas, without first becoming a liquid vaporisation when a liquid evaporates into a gas 14 Atoms and elements atom the smallest particle of matter which can exist alone It is made up of a nucleus with protons and neutrons, and electrons atomic number the number of protons in the nucleus of an atom This number is different for each atom chemical formula symbols which indicate how many atoms make up a molecule crystals consist of atoms or molecules arranged in a regular, organised structure electrons extremely small particles that orbit the nucleus They have a negative charge (–) and are attracted to the positively charged protons in the nucleus element a substance that contains just one type of atom It cannot be broken down into anything simpler by chemical reaction molecules two or more atoms joined together neutrons particles in the nucleus which have no charge periodic table of elements a table in which all elements are grouped with similar elements, with their symbol and atomic number protons particles in the atom’s nucleus, which have a positive charge 163 877306 _ 0164-0167.qxd 15/2/08 18:20 Página 164 Key language CLASSIFYING Non-silicates There are are classified into two groups of minerals five groups How many groups How are of non-silicates minerals Five Into two groups are there? classified? COMPARING Planets are The closest star bigger than to Earth is the Sun Are planets bigger than other celestial bodies other celestial bodies? Ocean trenches are the deepest areas The largest plains of on Where are the largest plains on the planet? Ferns Flowering plants the oceans the planet are under the oceans are bigger than mosses more complex Which group is bigger, ferns or mosses? Ferns The higher The higher a place is, the altitude, Where is it colder? The higher a place is, Talc is softer than apatite Is talc harder than the colder the lower it will be the density of the air the colder apatite? That box is four times bigger than this one Why does oil float on water? Because it is less dense Hydrogen and helium are the most abundant elements Which are the most abundant elements? it will be No, it isn’t in the Universe DESCRIBING The Sun Asteroids consists mainly of are What does the Sun consist of? Water There exists are How many states does water exist in? 164 hydrogen and helium rocky objects What are asteroids? in three states submarine volcanoes in the oceans Are there volcanoes in the oceans? 877306 _ 0164-0167.qxd 15/2/08 18:20 Página 165 DESCRIBING A bacteria does not have an organised nucleus Does a bacteria have an organised nucleus? No, it doesn’t Water Water is absorbs heat a powerful solvent What are two properties of water? Cohesion and adhesion Petroleum Mica is can be scratched Is How hard petroleum a mineral? is talc? A pure substance a rock with a fingernail No, it’s a rock It has a hardness of on the Mohs scale has Is sea water a homogeneous mixture? only one component Yes, it is Calcium is a greyish white metal What is potassium like? It is a soft, shiny metal DESCRIBING A PROCESS When minerals dissolve in water, raw sap When pollen penetrates the stigma, ovules When are ovules Igneous rocks How are is produced are fertilised fertilised? When pollen penetrates the stigma are formed as a result of igneons rocks When paper When you mix formed? is burned, sand and water, the solidification of magma By the effects of heart and pressure it changes into you get ashes a heterogeneous mixture When does sublimation occur? When a solid changes directly into a gas EXPRESSING FACTS Living things Inorganic substances What Do feed and reproduce not contain living things inorganic substances contain The Monera kingdom Most bacteria carbon do? carbon? contains not produce They reproduce No, they don’t unicellular organisms their own food EXPRESSING AMOUNTS The Earth’s atmosphere is about 800 km high How high is the atmosphere? About 800 km high 165 877306 _ 0164-0167.qxd 15/2/08 18:20 Página 166 EXPRESSING AMOUNTS 68.7% of fresh water is found in lakes How much salt What percentage of fresh water is there in sea water? About 35 grams is there on the Earth? Only 3% EXPRESSING CAUSE AND RESULT Water exists in three states The Earth looks blue due to because of temperature variations the water on its surface Why does the Earth look blue? Because of the water They undergo metamorphosis As a result, they develop lungs How amphibians develop lungs? As a result of metamorphosis EXPRESSING CONTRAST Some arthropods Most gastropods are have carnivores, a shell, but but others are herbivores slugs don’t Do all cephalopods have a shell? Are all arthropods carnivores? Most fish are covered with scales However, Do all fish have scales? Most However, a shark’s skin has denticles sharks have denticles EXPRESSING DIRECTION Water filters Waves transport sand into along the coast and the ground out to sea Where does water flow? To the sea, and into the ground EXPRESSING PURPOSE Water is necessary Living things need glucose to transport to get all other substances energy Why is water necessary? Why living things need glucose? To transport To get substances energy Reptiles have hard scales to keep them warm Why reptiles have hard scales? Ceramic materials are used for tiles and bricks How are rocks used? Which rock is used for roofs? GIVING INSTRUCTIONS Study Research 166 the constellations more about them on the Internet 877306 _ 0164-0167.qxd 15/2/08 18:20 Página 167 GIVING INSTRUCTIONS Label each jar Observe the samples INDICATING LOCATION Magnesium is found in minerals Where is magnesium found? In minerals MAKING GENERALISATIONS Most sponges Some molluscs live have in the sea no shell Where most sponges All Most plants gymnosperms Do have are all plants have roots? Most rocks Solutions contain can be live? roots evergreens Are all gymnosperms evergreens? a mixture of minerals solid, liquid or gaseous How many states of matter are there? Three MAKING IMPERSONAL STATEMENTS Systems are made up of several organs What are systems made up of? Some bodies What are divided are their bodies Some rocks Sedimentary rocks How are rocks The volume of a liquid A thermometer How is into segments like? can be broken into are found irregular shapes in strata classified? three main classes can be calculated is used surface area A series of segments measured? Into by measuring the container to measure temperature In square metres (m2) MEASURING The court Density is measured measures 18 by 15 metres in kilograms per cubic metre (Kg/m3) How cold is that? How is density measured? Minus 273.15ºC In kilograms per cubic metre 167 877306 _ 0168-0168.qxd 25/11/09 09:27 Página 168 Essential Natural Science is a collective work, conceived, designed and created by the Secondary Education department at Santillana, under the supervision of ENRIQUE JUAN REDAL, ANTONIO BRANDI and MICHELE C GUERRINI Content writers: Concha Barreiro, Marcos Blanco, Antonio Delgado, Belén Garrido, Pilar de Luis, Miguel Ángel Madrid, Ignacio Meléndez, Margarita Montes and Cristina Zarzuelo Content consultants: Kevin Salvage and Carmen Rengel Language specialists: María José Sánchez (Key language), María Rosa Batlle, Giselle Dubois, Paul House, Kate Marriage, Beatriz Papaseit and Ana María Pons English editors: Sheila Tourle, Sheila Klaiber, Kirsten Ruiz-McOmish, Rebecca Adlard and Patricia Gómez Student CD: Vocabulary organiser: Antonio Delgado Web tasks: Jeannette West Art director: José Crespo Design coordinator: Rosa Marín Design Team: Cover: Martín León-Barreto Interior: Manuel García, Alfredo Mateo Coordinator, design development: Javier Tejeda Design development: José Luis García and Raúl de Andrés Technical director: Ángel García Encinar Technical coordinator: Marisa Valbuena Layout: Alfredo Mateos, Javier Pulido Artwork coordinator: Carlos Aguilera Illustrations: alademoscail-lustració, Digitalartis, Marcelo Pérez, Pere Luis León Research and photographic selection: Amparo Rodríguez Photographs: A Toimil; A Toril; A Viñas; Algar; C Díez; C Jiménez; C Roca; C Suárez; C Valderrábano e I Hernández; D Lezama; D López; F de Santiago; F Gracia; F Ontañón; F Orte; F Po; G Rodríguez; GARCÍA-PELAYO/Juancho; I Rovira; I Sabater; J C Martínez; J C Muñoz/’Instituto Geológico y Minero de España’; J Escandell.com; J I Medina; J Jaime; J L G Grande; J Lucas; J M Borrero; J M.ª Barres; J M.ª Escudero; J Ruiz; J V Resino; Juan M Ruiz; Krauel; L M Iglesias; M Izquierdo; M.ª A Ferrándiz; Michele di Piccione; O Torres; P Anca; P Esgueva; P López; P Nadal; Prats i Camps; R Antunes; R Vela; Roca-Madariaga; S Cid; S Padura; Sánchez-Durán; X Andrés; A G E FOTOSTOCK/K H Jacobi, Andrew Syred, Tom Servais, Nacho Moro, Marevision, Dan Suzio, Jim Zipp, PIXTAL, CNRI, Dennis Kunkel, SPL, Claude Nuridsany & Marie Perennou, SCUBAZOO/Matthew Oldfield, Science Photo Library, Detlev Van Ravenswaay, Science Museum/SSPL, Dr Gary D Gaugler, Dr M A Ansary/SPL, Sinclair Stammers, Herman Eisenbeiss, Susumu Nishinaga, SCIENCE PHOTO LIBRARY, James Cavallini, CINTRACT Romain, Eye of Science; A.S.A./Minden Pictures/FOTO NATURA/Armin Maywald; ABB FOTÓGRAFOS/F Baixeras; ACTIVIDADES Y SERVICIOS FOTOGRÁFICOS/J Latova; ARIAS FORMATO PROFESIONAL/A Arias; COMSTOCK; CONTIFOTO/François Merlet, VISA REPORTAGE/X Desmier; COVER/POPPERFOTO; COVER/SYGMA/Dan Bool; COVER/CORBIS/Papilio/Bryan Knox, Tim Davis, EPA/Irwan; DIGITAL BANK; DIGITALVISION; EFE/AP PHOTO/The Miami Herald/Ron Magill, EPA PHOTO/FEATURECHINA, Alfredo Aldai, César Borja, M Martí, M Riopa, AP PHOTO/I UNDATED FILE PHOTO, AP PHOTO/NASA/EIT, SIPA SANTÉ/BN/SIPA ICONO; EFE/SIPA-PRESS/Lambert, Becker, David Howells, Dirk Heinrich, F Durand, Gerald Buthaud, Hulot, Leonide Principe, Pinson, Romuald Meigneux, S Corp., SEA WORLD (GATLEY); FOCOLTONE; FOTONONSTOP; GALICIA EDITORIAL/Miguel Villar; GETTY IMAGES SALES SPAIN; HIGHRES PRESS STOCK/AbleStock.com; I Preysler; JOHN FOXX IMAGES; LOBO PRODUCCIONES / C Sanz; MICROS/J M Blanco; MELBA AGENCY; NASA/Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE, NASA, ESA and A Nota (STScI/ESA), Credit Image created by Reto Stockli with the help of Alan Nelson, under the leadership of Fritz Hasler; PAISAJES ESPAÑOLES; PHOTODISC; SEIS X SEIS; STOCKBYTE; BUREAU INTERNATIONAL DES POIDS ET MESURE; C Brito/J Núñez; Calvin Hamilton; cortesía IBM; FUNDACIÓ ‘LA CAIXA’/Colección Fundació ‘La Caixa’; I Nieva; INSTITUTO GEOLÓGICO Y MINERO DE ESPAÑA; INSTITUTO NACIONAL DE METEOROLOGÍA, MADRID; M Falagán; M Vives; MATTON-BILD; MUSEO CAPITOLINO, ROMA; Parque Nacional Marítimo-Terrestre de las Islas Atlánticas, Galicia/Roberto Castiñeira; S Matellano; SERIDEC PHOTOIMAGENES CD/DIGITALVISION; T Grence; ARCHIVO SANTILLANA The publishers would like to express their gratitude to the following teachers for their insightful comments and useful suggestions throughout the preparation of Essential Natural Science Carlos Álvarez Santos, Silvia Durán, José Ramón Noya, Maureen Vidal Gafford © 2008 by Santillana Educación, S L / Richmond Publishing Torrelaguna, 60 28043 Madrid Richmond Publishing is an imprint of Santillana Educación, S L Richmond Publishing 58 St Aldates Oxford OX1 1ST PRINTED IN SPAIN Printed in Spain ISBN: 978-84-294-2222-1 CP: 877306 D.L.: All rights reserved No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission in writing of the publisher