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C1 1.1 ATOMS, ELEMENTS & COMPOUNDS All substances are made of atoms Elements are made of only one type of atom Compounds contain more than one type of.

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Presentation on theme: "C1 1.1 ATOMS, ELEMENTS & COMPOUNDS All substances are made of atoms Elements are made of only one type of atom Compounds contain more than one type of."— Presentation transcript:

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2 C1 1.1 ATOMS, ELEMENTS & COMPOUNDS All substances are made of atoms Elements are made of only one type of atom Compounds contain more than one type of atom Compounds are held together by bonds Each element has its own symbol in the periodic table Columns are called GROUPS. Elements in a group have similar properties Rows are called PERIODS The red staircase splits metals from non-metals An atom is made up of a tiny nucleus with electrons around it

3 C1 1.2 ATOMIC STRUCTURE Atoms contain PROTONS, NEUTRONS & ELECTRONS Protons and Neutrons are found in the NUCLEUS Electrons orbit the nucleus ATOMIC NUMBER  the number of protons in the nucleus  the periodic table is arranged in this order MASS NUMBER  the number of protons plus neutrons Number of neutrons = Mass Number – Atomic Number Any atom contains equal numbers of protons and electrons PARTICLERELATIVE CHARGE RELATIVE MASS Proton+1 (positive)1 Neutron0 (neutral)1 Electron-1 (negative)0

4 C1 1.3 ELECTRON ARRANGEMENT Electrons are arranged around the nucleus in SHELLS (or energy levels) The shell closest to the nucleus has the lowest energy Electrons occupy the lowest available energy level Atoms with the same number of electrons in the outer shell belong to the same GROUP in the periodic table Number of outer electrons determine the way an element reacts Atoms of the last group (noble gases) have stable arrangements and are unreactive This is how we draw atoms and their electrons Low energy shell High energy shell Sodium

5 C1 1.4 FORMING BONDS Atoms can react to form compounds in a number of ways: i)Transferring electrons  IONIC BONDING ii)Sharing electrons  COVALENT BONDING IONIC BONDING When a metal and non-metal react Metals form positive ions Non-metals from negative ions Opposite charges attract A giant lattice is formed COVALENT BONDING When 2 non-metals bond Outermost electrons are shared A pair of shared electrons forms a bond CHEMICAL FORMULAE Tells us the ratio of each element in the compound In ionic compounds the charges must cancel out: E.g. MgCl 2 We have 2 chloride ions for every magnesium ion

6 H 2 + O 2  H 2 O Add a 2 to the products side to make the oxygen balance H 2 + O 2  2H 2 O This has changed the number of hydrogen atoms so we must now adjust the reactant side: 2H 2 + O 2  2H 2 O C1 1.5 CHEMICAL EQUATIONS Chemical equations show the reactants (what we start with) and the products (what we end up with) We often use symbol equations to make life easier CaCO 3  CaO + CO 2 MAKING EQUATIONS BALANCE Equations MUST balance We can ONLY add BIG numbers to the front of a substance We can tell elements within a compound by BIG letters CaCO 3  this is a compound made of 3 elements (calcium, carbon and oxygen) Ca = 1 C = 1 O = 3 Ca = 1 C = 1 O = 3 This is balanced – same number of each type of atom on both sides of the equation We can check this by counting the number of each type on either side H = 2 O = 2 H = 2 O = 1 H = 2 O = 2 H = 4 O = 2

7 C1 2.1 LIMESTONE & ITS USES Limestone is made mainly of Calcium Carbonate Calcium carbonate has the chemical formulae CaCO 3 Some types of limestone (e.g. chalk) were formed from the remains of animals and plants that live millions of years ago USE IN BUILDING We use limestone in many buildings by cutting it into blocks. Other ways limestone is used: Cement = powdered limestone + powdered clay Concrete = Cement + Sand + Water HEATING LIMESTONE Breaking down a chemical by heating is called THERMAL DECOMPOSITION Calcium  Calcium + Carbon Carbonate Oxide Dioxide CaCO 3  CaO + CO 2 ROTARY LIME KILN This is the furnace used to heat lots of calcium carbonate and turn it into calcium oxide Calcium oxide is used in the building and agricultural industries

8 C1 2.2 REACTIONS OF CARBONATES Buildings made from limestone suffer from damage by acid rain This is because carbonates react with acid to form a salt, water and carbon dioxide Calcium + Hydrochloric  Calcium + Water + Carbon Carbonate Acid Chloride Dioxide CaCO 3 + 2HCl  CaCl 2 + H 2 O + CO 2 TESTING FOR CO 2 We use limewater to test for CO 2 Limewater turns cloudy A precipitate (tiny solid particles) of calcium carbonate forms causing the cloudiness! HEATING CARBONATES Metal carbonates decompose on heating to form the metal oxide and carbon dioxide MgCO 3  MgO + CO 2

9 C1 2.3 THE LIMESTONE REACTION CYCLE Limestone is used widely as a building material We can also use it to make other materials for the construction industry Calcium Carbonate + Heat  Calcium Oxide Calcium Oxide + Water  Calcium Hydroxide (Limewater) Calcium Carbonate Calcium Oxide Calcium Hydroxide Calcium Hydroxide Solution Step 1: Add Heat CaCO 3  CaO + CO 2 Step 2: Add a bit of water CaO + H 2 O  Ca(OH) 2 Step 3: Add more water & filter Ca(OH0) 2 + H 2 O  Ca(OH) 2 (aq) Step 4: Add CO 2 Ca(OH) 2 + CO 2  CaCO 3 + H 2 O Limestone

10 C1 2.4 CEMENT & CONCRETE CEMENT Made by heating limestone with clay in a kiln MORTAR Made by mixing cement and sand with water CONCRETE Made by mixing crushed rocks or stones (called aggregate), cement and sand with water C1 2.5 LIMESTONE ISSUES BENEFITS Provide jobs Lead to improved roads Filled in to make fishing lakes or for planting trees Can be used as landfill sites when finished with DRAWBACKS Destroys habitats Increased emissions Noisy & Dusty Dangerous areas for children Busier roads Ugly looking

11 C1 3.1 EXTRACTING METALS A metal compound within a rock is called an ORE The metal is often combined with oxygen Ores are mined from the ground and then purified Whether it’s worth extracting a particular metal depends on:  How easy it is to extract  How much metal the ore contains The reactivity series helps us decide the best way to extract a metal:  Metals below carbon in the series can be reduced by carbon to give the metal element  Metals more reactive than carbon cannot be extracted using carbon. Instead other methods like ELECTROLYSIS must be used THE REACTIVITY SERIES

12 C1 3.2 IRON & STEELS Iron Ore contains iron combined with oxygen We use a blast furnace and carbon to extract it (as it’s less reactive than carbon) Carbon REDUCES the iron oxide; Iron (III) Oxide + Carbon  Iron + Carbon Dioxide Iron from the blast furnace contains impurities:  Makes it hard and brittle  Can be run into moulds to form cast iron  Used in stoves & man-hole covers Removing all the carbon impurities gives us pure iron  Soft and easily shaped  Too soft for most uses  Need to combine it with other elements A metal mixed with other elements is called an ALLOY E.g. Steel  Iron with carbon and/or other elements There are a number of types of steel alloys:  Carbon steels  Low-alloy steels  High-alloy steels  Stainless steels

13 C1 3.3 ALUMINIUM & TITANIUM AluminiumTitanium Property Shiny Light Low density Conducts electricity and energy Malleable – easily shaped Ductile – drawn into cables and wires Strong Resistant to corrosion High melting point – so can be used at high temperatures Less dense than most metals Use Drinks cans Cooking foil Saucepans High-voltage electricity cables Bicycles Aeroplanes and space vehicles High-performance aircraft Racing bikes Jet engines Parts of nuclear reactors Replacement hip joints Extraction Electrolysis Aluminium ore is mined and extracted. Alumminium oxide (the ore) is melted Electric current passed through at high temperature  Expensive process – need lots of heat and electricity Displacement & Electrolysis Use sodium or potassium to displace titanium from its ore Get sodium and magnesium from electrolysis  Expensive – lots of steps involved, & needs lots of heat and electricity

14 C1 3.4 EXTRACTING COPPER COPPER-RICH ORES These contain lots of copper. There are 2 ways to consider: 1. Smelting 80% of copper is produced this way Heat copper ore strongly in a furnace with air Copper + Oxygen  Copper + Sulphur Sulphide Dioxide Then use electrolysis to purify the copper Expensive as needs lots of heat and electricity 2. Copper Sulphate Add sulphuric acid to a copper ore Produces copper sulphate Extract copper using electrolysis or displacement LOW GRADE COPPER ORES These contain smaller amount of copper. There are 2 main ways: 1. Phytomining Plants absorb copper ions from low- grade ore Plants are burned Copper ions dissolved by adding sulphuric acid Use displacement or electrolysis to extract pure copper 2. Bioleaching Bacteria feed on low-grade ore These produce a waste product that contains copper ions Use displacement or electrolysis to extract pure copper

15 C1 3.5 USEFUL METALS TRANSITION METALS Found in the central block of the periodic table Properties: Good conductors of electricity and energy Strong Malleable – easily bent into shape Uses: Buildings Transport (cars, trains etc) Heating systems Electrical wiring Example: Copper 1.Water pipes – easily bent into shape, strong, doesn’t react with water 2.Wires – ductile and conduct electricity COPPER ALLOYS Bronze – Copper + Tin - Tough - Resistant to corrosion Brass – Copper + Zinc - Harder but workable ALUMINIUM ALLOYS Alloyed with a wide range of other elements All have very different properties E.g. in aircraft or armour plating! GOLD ALLOYS Usually add Copper to make jewellery last longer

16 C1 3.6 METALLIC ISSUES EXPLOITING ORES Mining has many environmental consequences: Scar the landscape Noisy & Dusty Destroy animal habitats Large heaps of waste rock Make groundwater acidic Release gases that cause acid rain RECYCLING METALS Recycling aluminium saves 95% of the energy normally used to extract it! This saves money! Iron and steel are easily recycled. As they are magnetic they are easily separated Copper can be recycled too – but it’s trickier as it’s often alloyed with other elements BUILDING WITH METALS Benefits Steel is strong for girders Aluminium is corrosion resistant Many are malleable Copper is a good conductor and not reactive Drawbacks Iron & steel can rust Extraction causes pollution Metals are more expensive than other materials like concrete

17 C1 4.1 FUELS FROM CRUDE OIL CRUDE OIL A mixture of lots of different compounds [A mixture is 2 or more elements or compounds that are not chemically bonded together] We separate it into substances with similar boiling points These are called fractions This is done in a process called fractional distillation HYDROCARBONS Nearly all the compounds in crude oil are hydrocarbons Most of these are saturated hydrocarbons called alkanes Methane CH 4 Ethane C 2 H 6 Propane C 3 H 8 Butane C 4 H 10 General formula for an alkane is C n H (2n+2)

18 C1 4.2 FRACTIONAL DISTILLATION This is the process by which crude oil is separated into fractions  These are compounds with similar sized chains  Process relies on the boiling points of these compounds  The properties a fraction has depend on the size of their hydrocarbon chains SHORT CHAINS ARE:  Very flammable  Have low boiling points  Highly volatile (tend to turn into gases)  Have low viscosity (they flow easily) Long chains have the opposite of these! Crude oil fed in at the bottom Temperature decreases up the column Hydrocarbons with smaller chains found nearer the top

19 C1 4.3 BURNING FUELS COMPLETE COMBUSTION Lighter fractions from crude oil make good fuels They release energy when they are oxidised  burnt in oxygen: propane + oxygen  carbon dioxide + water POLLUTION Fossil fuels also produce a number of impurities when they are burnt These have negative effects on the environment The main pollutants are summarised below Sulphur Dioxide Poisonous gas It’s acidic Causes acid rain Causes engine corrosion Carbon Monoxide Produced when not enough oxygen Poisonous gas Prevents your blood carrying oxygen around your body Nitrogen Oxide Poisonous Trigger asthma attacks Can cause acid rain Particulates Tiny solid particles Contain carbon and unburnt hydrocarbon Carried in the air Damage cells in our lungs Cause cancer

20 C1 4.4 CLEANER FUELS Burning fuels releases pollutants that spread throughout the atmosphere: CATALYTIC CONVERTERS Reduces the carbon monoxide and nitrogen oxide produced They are expensive They don’t reduce the amount of CO 2 GLOBAL DIMMING Caused by particulates Reflect sunlight back into space Not as much light gets through to the Earth CARBON MONOXIDE Formed by incomplete combustion GLOBAL WARMING Caused by carbon dioxide Causing the average global temperature to increase SULPHUR DIOXIDE Caused by impurities in the fuel Affect asthma sufferers Cause acid rain  damages plants & buildings Carbon + Nitrogen  Carbon + Nitrogen Monoxide Oxide Dioxide

21 C1 4.5 ALTERNATIVE FUELS These are renewable fuels  sources of energy that could replace fossil fuels (coal, oil & gas) BIODIESELETHANOLHYDROGEN + Less harmful to animals Breaks down 5 × quicker Reduces particulates Making it produces other useful products ‘CO 2 neutral’ – plants grown to create it absorb the same amount of CO 2 generated when it’s burnt Easily made by fermenting sugar cane Gives off CO 2 but the sugar cane it comes from absorbs CO 2 when growing Very clean – no CO 2 Water is the only product - Large areas of farmland required Less food produced  Famine Destruction of habitats Freezes at low temps Large areas of farmland required Less food produced as people use it for fuel instead! Hydrogen is explosive Takes up a large volume  storage becomes an issue

22 C1 5.1 CRACKING HYDROCARBONS CRACKING  Breaking down large hydrocarbon chains into smaller, more useful ones SATURATED OR UNSATURATED? We can react products with bromine water to test for saturation: Positive Test: Unsaturated + Bromine  COLOURLESS hydrocarbon Water = ALKENES Negative Test: Saturated + Bromine  NO RECTION Hydrocarbon Water (orange) = ALKANES CRACKING PROCESS 1.Heat hydrocarbons to a high temp; then either: 2.Mix them with steam; OR 3.Pass the over a hot catalyst EXAMPLE OF CRACKING Cracking is a thermal decomposition reaction: C 10 H 22 C 5 H 12 + C 3 H 6 + C 2 H 4 ALKENES These are unsaturated hydrocarbons They contain a double bond Have the general formula  C n H 2n DecanePentanePropeneEthene 800 o C

23 C1 5.2 POLYMERS FROM ALKENES PLASTICS  Are made from lots of monomers joined together to make a polymer HOW DO MONOMERS JOIN TOGETHER? Double bond between carbons ‘opens up’ Replaced by single bonds as thousands of monomers join up It is called POLYMERISATION MONOMERSPOLYMER Ethene Poly(ethene) n Simplified way of writing it: ‘n’ represent a large repeating number

24 C1 5.3 NEW & USEFUL POLYMERS DESIGNER POLYMER  Polymer made to do a specific job Examples of uses for them: Dental fillings Linings for false teeth Packaging material Implants that release drugs slowly Light-Sensitive Plasters Top layer of plaster peeled back Lower layer now exposed to light Adhesive loses stickiness Peels easily off the skin SMART POLYMERS  Have their properties changed by light, temperature or other changes in their surroundings Hydrogels Have cross-linking chains Makes a matrix that traps water Act as wound dressings Let body heal in moist, sterile conditions Good for burns Shape memory polymers Wound is stitched loosely Temperature of the body makes the thread tighten Closes the wound up with the right amount of force

25 C1 5.4 PLASTIC WASTE NON-BIODEGRADABLE Don’t break down Litter the streets and shores Harm wildlife RECYCLING Sort plastics into different types Melted down and made into new products Saves energy and resources…BUT Hard to transport and Need to be sorted into specific types DISADVANTAGES OF BIODEGRADABLE PLASTICS Farmers sell crops like corn to make plastics Demand for food goes up Food prices go up  less can afford it  STARVATION Animal habitats destroyed to make new farmland Unsightly Last 100’s of years Fill up landfill sites BIODEGRADABLE PLASTICS Plastics that break down easily Granules of cornstarch are built into the plastic Microorganisms in soil feed on cornstarch This breaks the plastic down

26 C1 5.5 ETHANOL There are 2 main ways to make ethanol 2) ETHENE Hydration reaction  water is added Ethene + Steam  Ethanol C 2 H 4 + H 2 O  C 2 H 5 OH + Continuous process – lots made! + Produces no waste products - Requires lots of heat and energy - Relies on a non-renewable resource 1) FERMENTATION Sugar from plants is broken down by enzymes in yeast Sugar + Yeast  Ethanol + Carbon Dioxide 80% of ethanol is made this way + Uses renewable resources -Takes longer to produce - CO 2 is given off A molecule of ethanol HH-C-C-O H H H H USES FOR ETHANOL Alcohol Perfume Rocket Fuel Solvents Antiseptic wipes

27 C1 6.1 EXTRACTING VEGETABLE OIL There are 2 ways to extract vegetable oils from plants: 2) DISTILLATION 1.Plants are put into water and boiled 2.Oil and water evaporate together 3.Oil is collected by condensing (cooling the gas vapours) Lavender oil is one oil extracted this way 1) PRESSING 1.Farmers collect seeds from plants 2.Seeds are crushed and pressed 3.This extracts oil from them 4.Impurities are removed 5.Oil is processed to make it into a useful product FOOD AND FUEL Vegetable oils are important foods: Provide important nutrients (e.g. vitamin E) Contain lots of energy  so can also be used as fuels Unsaturated oils contain double bonds (C=C)  they decolourise Bromine water FoodEnergy (kJ) Veg Oil3900 Sugar1700 Meat1100 Table for info only – don’t memorise it!

28 C1 6.2 COOKING WITH VEGETABLE OILS COOKING IN OIL Food cooks quicker Outside becomes crispier Inside becomes softer Food absorbs some of the oil Higher energy content Too much is unhealthy HARDENING VEGETABLE OILS Reacting vegetable oils with HYDROGEN hardens them  increases melting points Makes them solid at room temperature  makes them into spreads! Double bonds converted to single bonds C=C  C-C Now called a HYDROGENATED OIL Reaction occurs at 60 o C with a nickel catalyst + 60 o C + Nickel catalyst Double bonds converted to single bonds Margarine

29 C1 6.3 EVERYDAY EMULSIONS Oils do not dissolve in water Emulsion  Where oil and water are dispersed (spread out) in each other  These often have special properties EMULSION EXAMPLES 1.Mayonnaise 2.Milk 3.Ice cream 4.Cosmetics – face cream, lipstick etc 5.Paint EMULSIFIERS Stop water and oil separating out into layers Emulsifiers have 2 parts that make them work: 1.Hydrophobic tail – is attracted to oil 2.Hydrophilic head – is attracted to water. It has a negative charge Oil droplet Emulsifier molecule Water -

30 C1 6.4 FOOD ISSUES E NUMBER Additives approved for use in Europe EMULSIFIERS Improve texture and taste of foods containing fats and oils Makes them more palatable (tasty) and tempting to eat! FOOD ADDITIVES Substance added to food to: Preserve it Improve its taste Improve its texture Improve its appearance VEG OILS Unsaturated Fats: Source of nutrients like vitamin E Keep arteries clear Reduce heart disease Lower cholesterol levels ANIMAL FATS Saturated Fats: Are not good for us Increase risk of heart disease Increase cholesterol E.g. chocolate!

31 C1 7.1 STRUCTURE OF THE EARTH Atmosphere: Most lies within 10km of the surface Rest is within 100km but it’s hard to judge! Crust: Solid 6km beneath oceans 35km beneath land Core: Made of nickel and iron Outer core is liquid Inner core is solid Radius is 3500km Mantle Behaves like a solid Can flow very slowly Is about 3000km deep!

32 C1 7.2 THE RESTLESS EARTH MOVING CONTINENTS The Earth’s crust and upper mantle are cracked into a number of pieces  TECTONIC PLATES These are constantly moving - just very slowly Motion is caused by CONVECTION CURRENTS in the mantle, due to radioactive decay PANGAEA If you look at the continents they roughly fit together Scientists think they were once one large land mass called pangaea, which then broke off into smaller chunks PLATE BOUNDARIES Earthquakes and volcanoes happen when tectonic plates meet These are very difficult to predict

33 C1 7.3 THE EARTH’S ATMOSPHERE IN THE PAST PHASE 1: PHASE 1: Volcanoes = Steam & CO 2 Volcanoes kept erupting giving out andVolcanoes kept erupting giving out Steam and CO 2 The early atmosphere was nearly all CO 2The early atmosphere was nearly all CO 2 The earth cooled and water vapour condensed to form the oceansThe earth cooled and water vapour condensed to form the oceans Like this for a billion years! PHASE 2: PHASE 2: Green Plants, Bacteria & Algae = Oxygen Green plants, bacteria and algae ran riot in the oceans!Green plants, bacteria and algae ran riot in the oceans! steadily by the process ofGreen plants steadily converted CO 2 into O 2 by the process of photosynthesis released byNitrogen released by denitrifying bacteria Plants colonise the land. Oxygen levels steadily increase PHASE 3: PHASE 3: Ozone Layer = Animals & Us The build up of O 2 killed off early organisms - allowing evolution of complex organismsThe build up of O 2 killed off early organisms - allowing evolution of complex organisms The created the which blocks harmful from the sunThe O 2 created the Ozone layer (O 3 ) which blocks harmful UV rays from the sun Virtually no CO 2 leftVirtually no CO 2 left

34 C1 7.4 LIFE ON EARTH No one can be sure how life on Earth first started. There are many different theories: MILLER-UREY EXPERIMENT Compounds for life on Earth came from reactions involving hydrocarbons (e.g. methane) and ammonia The energy for this could have been provided by lightning OTHER THEORIES 1.Molecules for life (amino acids) came on meteorites from out of space 2.Actual living organisms themselves arrived on meteorites 3.Biological molecules were released from deep ocean vents The experiment completed by Miller and Urey

35 C1 7.5 GASES IN THE ATMOSPHERE THE ATMOSPHERE TODAY: The main gases in the atmosphere today are: 1.Nitrogen  78% 2.Oxygen  21% 3.Argon  0.9% 4.Carbon Dioxide  0.04% CARBON DIOXIDE: Taken in by plants during photosynthesis When plants and animals die carbon is transferred to rocks Some forms fossil fuels which are released into the atmosphere when burnt The main gases in air can be separated out by fractional distillation. These gases are useful in industry

36 C1 7.6 CARBON DIOXIDE IN THE ATMOSPHERE The stages in the cycle are shown below: Carbon moves into and out of the atmosphere due to Plants – photosynthesis & decay Animals – respiration & decay Oceans – store CO 2 Rocks – store CO 2 and release it when burnt CO 2 LEVELS Have increased in the atmosphere recently largely due to the amount of fossil fuels we now burn

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38 Cracking involves breaking down larger crude oil fractions into smaller more useful hydrocarbons. This reaction involves heating the crude oil fraction to a high temperature so that it vaporises. The vapour is then passed over a catalyst or mixed with steam. Cracking is a thermal decomposition reaction - large molecules are broken into smaller molecules using heat Here is an example of cracking: 800°C + Catalyst C 10 H > C 5 H 12 + C 3 H 6 + C 2 H 4 Decane Pentane Propene Ethene Bromine water can be used to test a compound to see if its an alkane or alkene. It stays orange if a compound is saturated. It turns colourless if a compound is unsaturated. Crude oil can be used to make plastics using a process called polymerisation. This process involves joining together small molecules known as monomers into large molecules known as polymers. C1 Products from oil Polymerisation of ethene can represented like this: Biodegradable plastics are made partly using corn starch, which microorganisms feed on to break it down. However, growing corn starch for fuel and plastics could raise food prices, destroy habitats and cause global warming. Ethanol is an alcohol. Ethanol for use in drinks is made by fermentation of sugar using yeast: sugar >ethanol + carbon dioxide The ethanol is produced in batches and gives off CO 2, a greenhouse gas. Ethanol for use as a fuel or a solvent can be made from ethene and steam. This is a hydration reaction. It does not give off CO 2 and is a continuous process. However, ethene comes from crude oil, which means it is a non- renewable production method. Alkenes are produced during cracking. These are unsaturated hydrocarbons which means they contain a double bond. Their general formula is CnH 2 n Ethene Propene (C 2 H 4 ) (C 3 H 6 ) Ethene can be polymerised to make (poly)ethene, used for carrier bags and drinks bottles because it strong and transparent. Propene can be polymerised to form (poly)propene, a strong and tough plastic used for carpets and rope. Smart polymers like shape memory polymers, change shape when they are hot or cold. Stitches that tighten due to the body’s temperature and then later dissolve are being developed. PET is the plastic used for drinks bottles because it is strong, light, waterproof and transparent. These properties mean it can be recycled for hiking jackets. Designer polymers are materials that chemists make with specific properties for a certain job. Light sensitive plasters cause less pain when removed.

39 ___________involves breaking down larger crude oil fractions into _________ more _______ hydrocarbons. This reaction involves heating the crude oil fraction to a high ___________so that it ________. The vapour is then passed over a _________ or mixed with _____. Cracking is a _________ ________ reaction - ____ molecules are broken into _______ molecules using _______ Here is an example of cracking: 800°C + Catalyst C 10 H > C 5 H C 2 H 4 Decane _______ Propene ______ __________ can be used to test a compound to see if its an alkane or alkene. It stays _______ if a compound is ____________ It turns ____________ if a compound is ______________. Crude oil can be used to make plastics using a process called __________. This process involves joining together small molecules known as __________ into large molecules known as ___________. C1 Products from oil Polymerisation of ethene can represented like this: ___________ plastics are made partly using _________, which ___________ feed on to break it down. However, growing corn starch for ____and ______ could raise _________, destroy _______ and cause ______________. _________ is an ________. Ethanol for use in drinks is made by ___________of sugar using ______. sugar >ethanol + carbon dioxide The ethanol is produced in ______and gives off CO 2, a greenhouse gas. Ethanol for use as a fuel or a solvent can be made from ________and _______. This is a _________ reaction. It does not give off ___ and is a _________ process. However, ethene comes from _______ which means it is a _____________ production method. _______ are produced during cracking. These are __________ hydrocarbons which means they contain a ________ bond. Their general formula is _______ Ethene (C 2 H 4 ) Ethene can be polymerised to make ________________ used for carrier bags and drinks bottles because it _________ and ____________. Propene can be polymerised to form _____________ a strong and tough plastic used for _______ and ________. _______polymers like ________ _______polymers, change shape when they are hot or cold. Stitches that tighten due to the body’s ___________and then later ______ are being developed. PET is the plastic used for drinks bottles because it is ______, _______, _______ and _______. These properties mean it can be ________for hiking ______. _____________are materials that chemists make with specific properties for a certain job. _________plasters cause less pain when removed.

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41 C1 1.1 ATOMS, ELEMENTS & COMPOUNDS All substances are made of atoms Elements are made of only one type of atom Compounds contain more than one type of atom Compounds are held together by bonds Each element has its own symbol in the periodic table Columns are called GROUPS. Elements in a group have similar properties Rows are called PERIODS The red staircase splits metals from non-metals An atom is made up of a tiny nucleus with electrons around it

42 C1 1.2 ATOMIC STRUCTURE Atoms contain PROTONS, NEUTRONS & ELECTRONS Protons and Neutrons are found in the NUCLEUS Electrons orbit the nucleus ATOMIC NUMBER  the number of protons in the nucleus  the periodic table is arranged in this order MASS NUMBER  the number of protons plus neutrons Number of neutrons = Mass Number – Atomic Number Any atom contains equal numbers of protons and electrons PARTICLERELATIVE CHARGE RELATIVE MASS Proton+1 (positive)1 Neutron0 (neutral)1 Electron-1 (negative)0

43 C1 1.3 ELECTRON ARRANGEMENT Electrons are arranged around the nucleus in SHELLS (or energy levels) The shell closest to the nucleus has the lowest energy Electrons occupy the lowest available energy level Atoms with the same number of electrons in the outer shell belong to the same GROUP in the periodic table Number of outer electrons determine the way an element reacts Atoms of the last group (noble gases) have stable arrangements and are unreactive This is how we draw atoms and their electrons Low energy shell High energy shell Sodium

44 C1 1.4 FORMING BONDS Atoms can react to form compounds in a number of ways: i)Transferring electrons  IONIC BONDING ii)Sharing electrons  COVALENT BONDING IONIC BONDING When a metal and non-metal react Metals form positive ions Non-metals from negative ions Opposite charges attract A giant lattice is formed COVALENT BONDING When 2 non-metals bond Outermost electrons are shared A pair of shared electrons forms a bond CHEMICAL FORMULAE Tells us the ratio of each element in the compound In ionic compounds the charges must cancel out: E.g. MgCl 2 We have 2 chloride ions for every magnesium ion

45 H 2 + O 2  H 2 O Add a 2 to the products side to make the oxygen balance H 2 + O 2  2H 2 O This has changed the number of hydrogen atoms so we must now adjust the reactant side: 2H 2 + O 2  2H 2 O C1 1.5 CHEMICAL EQUATIONS Chemical equations show the reactants (what we start with) and the products (what we end up with) We often use symbol equations to make life easier CaCO 3  CaO + CO 2 MAKING EQUATIONS BALANCE Equations MUST balance We can ONLY add BIG numbers to the front of a substance We can tell elements within a compound by BIG letters CaCO 3  this is a compound made of 3 elements (calcium, carbon and oxygen) Ca = 1 C = 1 O = 3 Ca = 1 C = 1 O = 3 This is balanced – same number of each type of atom on both sides of the equation We can check this by counting the number of each type on either side H = 2 O = 2 H = 2 O = 1 H = 2 O = 2 H = 4 O = 2

46 C1 2.1 LIMESTONE & ITS USES Limestone is made mainly of Calcium Carbonate Calcium carbonate has the chemical formulae CaCO 3 Some types of limestone (e.g. chalk) were formed from the remains of animals and plants that live millions of years ago USE IN BUILDING We use limestone in many buildings by cutting it into blocks. Other ways limestone is used: Cement = powdered limestone + powdered clay Concrete = Cement + Sand + Water HEATING LIMESTONE Breaking down a chemical by heating is called THERMAL DECOMPOSITION Calcium  Calcium + Carbon Carbonate Oxide Dioxide CaCO 3  CaO + CO 2 ROTARY LIME KILN This is the furnace used to heat lots of calcium carbonate and turn it into calcium oxide Calcium oxide is used in the building and agricultural industries

47 C1 2.2 REACTIONS OF CARBONATES Buildings made from limestone suffer from damage by acid rain This is because carbonates react with acid to form a salt, water and carbon dioxide Calcium + Hydrochloric  Calcium + Water + Carbon Carbonate Acid Chloride Dioxide CaCO 3 + 2HCl  CaCl 2 + H 2 O + CO 2 TESTING FOR CO 2 We use limewater to test for CO 2 Limewater turns cloudy A precipitate (tiny solid particles) of calcium carbonate forms causing the cloudiness! HEATING CARBONATES Metal carbonates decompose on heating to form the metal oxide and carbon dioxide MgCO 3  MgO + CO 2

48 C1 2.3 THE LIMESTONE REACTION CYCLE Limestone is used widely as a building material We can also use it to make other materials for the construction industry Calcium Carbonate + Heat  Calcium Oxide Calcium Oxide + Water  Calcium Hydroxide (Limewater) Calcium Carbonate Calcium Oxide Calcium Hydroxide Calcium Hydroxide Solution Step 1: Add Heat CaCO 3  CaO + CO 2 Step 2: Add a bit of water CaO + H 2 O  Ca(OH) 2 Step 3: Add more water & filter Ca(OH0) 2 + H 2 O  Ca(OH) 2 (aq) Step 4: Add CO 2 Ca(OH) 2 + CO 2  CaCO 3 + H 2 O Limestone

49 C1 2.4 CEMENT & CONCRETE CEMENT Made by heating limestone with clay in a kiln MORTAR Made by mixing cement and sand with water CONCRETE Made by mixing crushed rocks or stones (called aggregate), cement and sand with water C1 2.5 LIMESTONE ISSUES BENEFITS Provide jobs Lead to improved roads Filled in to make fishing lakes or for planting trees Can be used as landfill sites when finished with DRAWBACKS Destroys habitats Increased emissions Noisy & Dusty Dangerous areas for children Busier roads Ugly looking

50 C1 3.1 EXTRACTING METALS A metal compound within a rock is called an ORE The metal is often combined with oxygen Ores are mined from the ground and then purified Whether it’s worth extracting a particular metal depends on:  How easy it is to extract  How much metal the ore contains The reactivity series helps us decide the best way to extract a metal:  Metals below carbon in the series can be reduced by carbon to give the metal element  Metals more reactive than carbon cannot be extracted using carbon. Instead other methods like ELECTROLYSIS must be used THE REACTIVITY SERIES

51 C1 3.2 IRON & STEELS Iron Ore contains iron combined with oxygen We use a blast furnace and carbon to extract it (as it’s less reactive than carbon) Carbon REDUCES the iron oxide; Iron (III) Oxide + Carbon  Iron + Carbon Dioxide Iron from the blast furnace contains impurities:  Makes it hard and brittle  Can be run into moulds to form cast iron  Used in stoves & man-hole covers Removing all the carbon impurities gives us pure iron  Soft and easily shaped  Too soft for most uses  Need to combine it with other elements A metal mixed with other elements is called an ALLOY E.g. Steel  Iron with carbon and/or other elements There are a number of types of steel alloys:  Carbon steels  Low-alloy steels  High-alloy steels  Stainless steels

52 C1 3.3 ALUMINIUM & TITANIUM AluminiumTitanium Property Shiny Light Low density Conducts electricity and energy Malleable – easily shaped Ductile – drawn into cables and wires Strong Resistant to corrosion High melting point – so can be used at high temperatures Less dense than most metals Use Drinks cans Cooking foil Saucepans High-voltage electricity cables Bicycles Aeroplanes and space vehicles High-performance aircraft Racing bikes Jet engines Parts of nuclear reactors Replacement hip joints Extraction Electrolysis Aluminium ore is mined and extracted. Alumminium oxide (the ore) is melted Electric current passed through at high temperature  Expensive process – need lots of heat and electricity Displacement & Electrolysis Use sodium or potassium to displace titanium from its ore Get sodium and magnesium from electrolysis  Expensive – lots of steps involved, & needs lots of heat and electricity

53 C1 3.4 EXTRACTING COPPER COPPER-RICH ORES These contain lots of copper. There are 2 ways to consider: 1. Smelting 80% of copper is produced this way Heat copper ore strongly in a furnace with air Copper + Oxygen  Copper + Sulphur Sulphide Dioxide Then use electrolysis to purify the copper Expensive as needs lots of heat and electricity 2. Copper Sulphate Add sulphuric acid to a copper ore Produces copper sulphate Extract copper using electrolysis or displacement LOW GRADE COPPER ORES These contain smaller amount of copper. There are 2 main ways: 1. Phytomining Plants absorb copper ions from low- grade ore Plants are burned Copper ions dissolved by adding sulphuric acid Use displacement or electrolysis to extract pure copper 2. Bioleaching Bacteria feed on low-grade ore These produce a waste product that contains copper ions Use displacement or electrolysis to extract pure copper

54 C1 3.5 USEFUL METALS TRANSITION METALS Found in the central block of the periodic table Properties: Good conductors of electricity and energy Strong Malleable – easily bent into shape Uses: Buildings Transport (cars, trains etc) Heating systems Electrical wiring Example: Copper 1.Water pipes – easily bent into shape, strong, doesn’t react with water 2.Wires – ductile and conduct electricity COPPER ALLOYS Bronze – Copper + Tin - Tough - Resistant to corrosion Brass – Copper + Zinc - Harder but workable ALUMINIUM ALLOYS Alloyed with a wide range of other elements All have very different properties E.g. in aircraft or armour plating! GOLD ALLOYS Usually add Copper to make jewellery last longer

55 C1 3.6 METALLIC ISSUES EXPLOITING ORES Mining has many environmental consequences: Scar the landscape Noisy & Dusty Destroy animal habitats Large heaps of waste rock Make groundwater acidic Release gases that cause acid rain RECYCLING METALS Recycling aluminium saves 95% of the energy normally used to extract it! This saves money! Iron and steel are easily recycled. As they are magnetic they are easily separated Copper can be recycled too – but it’s trickier as it’s often alloyed with other elements BUILDING WITH METALS Benefits Steel is strong for girders Aluminium is corrosion resistant Many are malleable Copper is a good conductor and not reactive Drawbacks Iron & steel can rust Extraction causes pollution Metals are more expensive than other materials like concrete

56 C1 4.1 FUELS FROM CRUDE OIL CRUDE OIL A mixture of lots of different compounds [A mixture is 2 or more elements or compounds that are not chemically bonded together] We separate it into substances with similar boiling points These are called fractions This is done in a process called fractional distillation HYDROCARBONS Nearly all the compounds in crude oil are hydrocarbons Most of these are saturated hydrocarbons called alkanes Methane CH 4 Ethane C 2 H 6 Propane C 3 H 8 Butane C 4 H 10 General formula for an alkane is C n H (2n+2)

57 C1 4.2 FRACTIONAL DISTILLATION This is the process by which crude oil is separated into fractions  These are compounds with similar sized chains  Process relies on the boiling points of these compounds  The properties a fraction has depend on the size of their hydrocarbon chains SHORT CHAINS ARE:  Very flammable  Have low boiling points  Highly volatile (tend to turn into gases)  Have low viscosity (they flow easily) Long chains have the opposite of these! Crude oil fed in at the bottom Temperature decreases up the column Hydrocarbons with smaller chains found nearer the top

58 C1 4.3 BURNING FUELS COMPLETE COMBUSTION Lighter fractions from crude oil make good fuels They release energy when they are oxidised  burnt in oxygen: propane + oxygen  carbon dioxide + water POLLUTION Fossil fuels also produce a number of impurities when they are burnt These have negative effects on the environment The main pollutants are summarised below Sulphur Dioxide Poisonous gas It’s acidic Causes acid rain Causes engine corrosion Carbon Monoxide Produced when not enough oxygen Poisonous gas Prevents your blood carrying oxygen around your body Nitrogen Oxide Poisonous Trigger asthma attacks Can cause acid rain Particulates Tiny solid particles Contain carbon and unburnt hydrocarbon Carried in the air Damage cells in our lungs Cause cancer

59 C1 4.4 CLEANER FUELS Burning fuels releases pollutants that spread throughout the atmosphere: CATALYTIC CONVERTERS Reduces the carbon monoxide and nitrogen oxide produced They are expensive They don’t reduce the amount of CO 2 GLOBAL DIMMING Caused by particulates Reflect sunlight back into space Not as much light gets through to the Earth CARBON MONOXIDE Formed by incomplete combustion GLOBAL WARMING Caused by carbon dioxide Causing the average global temperature to increase SULPHUR DIOXIDE Caused by impurities in the fuel Affect asthma sufferers Cause acid rain  damages plants & buildings Carbon + Nitrogen  Carbon + Nitrogen Monoxide Oxide Dioxide

60 C1 4.5 ALTERNATIVE FUELS These are renewable fuels  sources of energy that could replace fossil fuels (coal, oil & gas) BIODIESELETHANOLHYDROGEN + Less harmful to animals Breaks down 5 × quicker Reduces particulates Making it produces other useful products ‘CO 2 neutral’ – plants grown to create it absorb the same amount of CO 2 generated when it’s burnt Easily made by fermenting sugar cane Gives off CO 2 but the sugar cane it comes from absorbs CO 2 when growing Very clean – no CO 2 Water is the only product - Large areas of farmland required Less food produced  Famine Destruction of habitats Freezes at low temps Large areas of farmland required Less food produced as people use it for fuel instead! Hydrogen is explosive Takes up a large volume  storage becomes an issue

61 C1 5.1 CRACKING HYDROCARBONS CRACKING  Breaking down large hydrocarbon chains into smaller, more useful ones SATURATED OR UNSATURATED? We can react products with bromine water to test for saturation: Positive Test: Unsaturated + Bromine  COLOURLESS hydrocarbon Water = ALKENES Negative Test: Saturated + Bromine  NO RECTION Hydrocarbon Water (orange) = ALKANES CRACKING PROCESS 1.Heat hydrocarbons to a high temp; then either: 2.Mix them with steam; OR 3.Pass the over a hot catalyst EXAMPLE OF CRACKING Cracking is a thermal decomposition reaction: C 10 H 22 C 5 H 12 + C 3 H 6 + C 2 H 4 ALKENES These are unsaturated hydrocarbons They contain a double bond Have the general formula  C n H 2n DecanePentanePropeneEthene 800 o C

62 C1 5.2 POLYMERS FROM ALKENES PLASTICS  Are made from lots of monomers joined together to make a polymer HOW DO MONOMERS JOIN TOGETHER? Double bond between carbons ‘opens up’ Replaced by single bonds as thousands of monomers join up It is called POLYMERISATION MONOMERSPOLYMER Ethene Poly(ethene) n Simplified way of writing it: ‘n’ represent a large repeating number

63 C1 5.3 NEW & USEFUL POLYMERS DESIGNER POLYMER  Polymer made to do a specific job Examples of uses for them: Dental fillings Linings for false teeth Packaging material Implants that release drugs slowly Light-Sensitive Plasters Top layer of plaster peeled back Lower layer now exposed to light Adhesive loses stickiness Peels easily off the skin SMART POLYMERS  Have their properties changed by light, temperature or other changes in their surroundings Hydrogels Have cross-linking chains Makes a matrix that traps water Act as wound dressings Let body heal in moist, sterile conditions Good for burns Shape memory polymers Wound is stitched loosely Temperature of the body makes the thread tighten Closes the wound up with the right amount of force

64 C1 5.4 PLASTIC WASTE NON-BIODEGRADABLE Don’t break down Litter the streets and shores Harm wildlife RECYCLING Sort plastics into different types Melted down and made into new products Saves energy and resources…BUT Hard to transport and Need to be sorted into specific types DISADVANTAGES OF BIODEGRADABLE PLASTICS Farmers sell crops like corn to make plastics Demand for food goes up Food prices go up  less can afford it  STARVATION Animal habitats destroyed to make new farmland Unsightly Last 100’s of years Fill up landfill sites BIODEGRADABLE PLASTICS Plastics that break down easily Granules of cornstarch are built into the plastic Microorganisms in soil feed on cornstarch This breaks the plastic down

65 C1 5.5 ETHANOL There are 2 main ways to make ethanol 2) ETHENE Hydration reaction  water is added Ethene + Steam  Ethanol C 2 H 4 + H 2 O  C 2 H 5 OH + Continuous process – lots made! + Produces no waste products - Requires lots of heat and energy - Relies on a non-renewable resource 1) FERMENTATION Sugar from plants is broken down by enzymes in yeast Sugar + Yeast  Ethanol + Carbon Dioxide 80% of ethanol is made this way + Uses renewable resources -Takes longer to produce - CO 2 is given off A molecule of ethanol HH-C-C-O H H H H USES FOR ETHANOL Alcohol Perfume Rocket Fuel Solvents Antiseptic wipes

66 C1 6.1 EXTRACTING VEGETABLE OIL There are 2 ways to extract vegetable oils from plants: 2) DISTILLATION 1.Plants are put into water and boiled 2.Oil and water evaporate together 3.Oil is collected by condensing (cooling the gas vapours) Lavender oil is one oil extracted this way 1) PRESSING 1.Farmers collect seeds from plants 2.Seeds are crushed and pressed 3.This extracts oil from them 4.Impurities are removed 5.Oil is processed to make it into a useful product FOOD AND FUEL Vegetable oils are important foods: Provide important nutrients (e.g. vitamin E) Contain lots of energy  so can also be used as fuels Unsaturated oils contain double bonds (C=C)  they decolourise Bromine water FoodEnergy (kJ) Veg Oil3900 Sugar1700 Meat1100 Table for info only – don’t memorise it!

67 C1 6.2 COOKING WITH VEGETABLE OILS COOKING IN OIL Food cooks quicker Outside becomes crispier Inside becomes softer Food absorbs some of the oil Higher energy content Too much is unhealthy HARDENING VEGETABLE OILS Reacting vegetable oils with HYDROGEN hardens them  increases melting points Makes them solid at room temperature  makes them into spreads! Double bonds converted to single bonds C=C  C-C Now called a HYDROGENATED OIL Reaction occurs at 60 o C with a nickel catalyst + 60 o C + Nickel catalyst Double bonds converted to single bonds Margarine

68 C1 6.3 EVERYDAY EMULSIONS Oils do not dissolve in water Emulsion  Where oil and water are dispersed (spread out) in each other  These often have special properties EMULSION EXAMPLES 1.Mayonnaise 2.Milk 3.Ice cream 4.Cosmetics – face cream, lipstick etc 5.Paint EMULSIFIERS Stop water and oil separating out into layers Emulsifiers have 2 parts that make them work: 1.Hydrophobic tail – is attracted to oil 2.Hydrophilic head – is attracted to water. It has a negative charge Oil droplet Emulsifier molecule Water -

69 C1 6.4 FOOD ISSUES E NUMBER Additives approved for use in Europe EMULSIFIERS Improve texture and taste of foods containing fats and oils Makes them more palatable (tasty) and tempting to eat! FOOD ADDITIVES Substance added to food to: Preserve it Improve its taste Improve its texture Improve its appearance VEG OILS Unsaturated Fats: Source of nutrients like vitamin E Keep arteries clear Reduce heart disease Lower cholesterol levels ANIMAL FATS Saturated Fats: Are not good for us Increase risk of heart disease Increase cholesterol E.g. chocolate!

70 C1 7.1 STRUCTURE OF THE EARTH Atmosphere: Most lies within 10km of the surface Rest is within 100km but it’s hard to judge! Crust: Solid 6km beneath oceans 35km beneath land Core: Made of nickel and iron Outer core is liquid Inner core is solid Radius is 3500km Mantle Behaves like a solid Can flow very slowly Is about 3000km deep!

71 C1 7.2 THE RESTLESS EARTH MOVING CONTINENTS The Earth’s crust and upper mantle are cracked into a number of pieces  TECTONIC PLATES These are constantly moving - just very slowly Motion is caused by CONVECTION CURRENTS in the mantle, due to radioactive decay PANGAEA If you look at the continents they roughly fit together Scientists think they were once one large land mass called pangaea, which then broke off into smaller chunks PLATE BOUNDARIES Earthquakes and volcanoes happen when tectonic plates meet These are very difficult to predict

72 C1 7.3 THE EARTH’S ATMOSPHERE IN THE PAST PHASE 1: PHASE 1: Volcanoes = Steam & CO 2 Volcanoes kept erupting giving out andVolcanoes kept erupting giving out Steam and CO 2 The early atmosphere was nearly all CO 2The early atmosphere was nearly all CO 2 The earth cooled and water vapour condensed to form the oceansThe earth cooled and water vapour condensed to form the oceans Like this for a billion years! PHASE 2: PHASE 2: Green Plants, Bacteria & Algae = Oxygen Green plants, bacteria and algae ran riot in the oceans!Green plants, bacteria and algae ran riot in the oceans! steadily by the process ofGreen plants steadily converted CO 2 into O 2 by the process of photosynthesis released byNitrogen released by denitrifying bacteria Plants colonise the land. Oxygen levels steadily increase PHASE 3: PHASE 3: Ozone Layer = Animals & Us The build up of O 2 killed off early organisms - allowing evolution of complex organismsThe build up of O 2 killed off early organisms - allowing evolution of complex organisms The created the which blocks harmful from the sunThe O 2 created the Ozone layer (O 3 ) which blocks harmful UV rays from the sun Virtually no CO 2 leftVirtually no CO 2 left

73 C1 7.4 LIFE ON EARTH No one can be sure how life on Earth first started. There are many different theories: MILLER-UREY EXPERIMENT Compounds for life on Earth came from reactions involving hydrocarbons (e.g. methane) and ammonia The energy for this could have been provided by lightning OTHER THEORIES 1.Molecules for life (amino acids) came on meteorites from out of space 2.Actual living organisms themselves arrived on meteorites 3.Biological molecules were released from deep ocean vents The experiment completed by Miller and Urey

74 C1 7.5 GASES IN THE ATMOSPHERE THE ATMOSPHERE TODAY: The main gases in the atmosphere today are: 1.Nitrogen  78% 2.Oxygen  21% 3.Argon  0.9% 4.Carbon Dioxide  0.04% CARBON DIOXIDE: Taken in by plants during photosynthesis When plants and animals die carbon is transferred to rocks Some forms fossil fuels which are released into the atmosphere when burnt The main gases in air can be separated out by fractional distillation. These gases are useful in industry

75 C1 7.6 CARBON DIOXIDE IN THE ATMOSPHERE The stages in the cycle are shown below: Carbon moves into and out of the atmosphere due to Plants – photosynthesis & decay Animals – respiration & decay Oceans – store CO 2 Rocks – store CO 2 and release it when burnt CO 2 LEVELS Have increased in the atmosphere recently largely due to the amount of fossil fuels we now burn


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