C1 1.1 ATOMS, ELEMENTS & COMPOUNDS

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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 atom
• Compounds are held together by bonds

An atom is made up of a tiny nucleus with
electrons around it

• 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

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C1 1.2 ATOMIC STRUCTURE

• Atoms contain PROTONS, NEUTRONS ELECTRONS
• Protons and Neutrons are found in the NUCLEUS
• Electrons orbit the nucleus

PARTICLE RELATIVE CHARGE RELATIVE MASS
Proton 1 (positive) 1
Neutron 0 (neutral) 1
Electron -1 (negative) 0
Any atom contains equal numbers of protons and
electrons

• 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

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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

High energy shell
This is how we draw atoms and their electrons
Low energy shell
Sodium

• 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

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C1 1.4 FORMING BONDS

• Atoms can react to form compounds in a number of
  ways
• Transferring electrons ? IONIC BONDING
• 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. MgCl2
• We have 2 chloride ions for every magnesium ion

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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
• CaCO3 ? CaO CO2

• 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

Ca 1 C 1 O 3
Ca 1 C 1 O 3
H2 O2 ? H2O Add a 2 to the products
side to make the oxygen balance H2 O2 ?
2H2O This has changed the number of hydrogen
atoms so we must now adjust the reactant
side 2H2 O2 ? 2H2O
MAKING EQUATIONS BALANCEEquations MUST
balance We can ONLY add BIG numbers to the front
of a substance We can tell elements within a
compound by BIG letters CaCO3 ? this is a
compound made of 3 elements (calcium, carbon and
oxygen)
H 2 O 2
H 2 O 1
H 2 O 2
H 4 O 2
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C1 2.1 LIMESTONE ITS USES

• Limestone is made mainly of Calcium Carbonate
• Calcium carbonate has the chemical formulae CaCO3
• 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 CaCO3 ?
CaO CO2
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
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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
• CaCO3 2HCl ? CaCl2 H2O CO2

• TESTING FOR CO2
• We use limewater to test for CO2
• 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 MgCO3 ? MgO CO2
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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
Step 4 Add CO2 Ca(OH)2 CO2 ? CaCO3 H2O
Step 1 Add Heat CaCO3 ? CaO CO2
Limestone
Calcium Oxide
Calcium Hydroxide Solution
Step 2 Add a bit of water CaO H2O ? Ca(OH)2
Step 3 Add more water filter Ca(OH0)2 H2O
? Ca(OH)2 (aq)
Calcium Hydroxide
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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

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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 its 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
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C1 3.2 IRON STEELS

• Iron Ore contains iron combined with oxygen
• We use a blast furnace and carbon to extract it
  (as its 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
  elementsThere are a number of types of steel
  alloys
• Carbon steels
• Low-alloy steels
• High-alloy steels
• Stainless steels

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C1 3.3 ALUMINIUM TITANIUM
Aluminium Titanium
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
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C1 3.4 EXTRACTING COPPER

• COPPER-RICH ORESThese contain lots of copper.
  There are 2 ways to consider1. Smelting
• 80 of copper is produced this way
• Heat copper ore strongly in a furnace with air
• Copper Oxygen ? Copper
  SulphurSulphide
  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 ORESThese contain smaller
  amount of copper. There are 2 main ways1.
  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
  copper2. Bioleaching
• Bacteria feed on low-grade ore
• These produce a waste product that contains
  copper ions
• Use displacement or electrolysis to extract pure
  copper

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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
• Water pipes easily bent into shape, strong,
  doesnt react with water
• 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

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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 its trickier as
  its 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

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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
General formula for an alkane is CnH(2n2)
Methane CH4
Ethane C2H6
Propane C3H8
Butane C4H10
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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
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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

• Particulates
• Tiny solid particles
• Contain carbon and unburnt hydrocarbon
• Carried in the air
• Damage cells in our lungs
• Cause cancer

• Sulphur Dioxide
• Poisonous gas
• Its 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

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C1 4.4 CLEANER FUELS
Burning fuels releases pollutants that spread
throughout the atmosphere

• 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

• CATALYTIC CONVERTERS
• Reduces the carbon monoxide and nitrogen oxide
  produced
• They are expensive
• They dont reduce the amount of CO2

Carbon Nitrogen ? Carbon
NitrogenMonoxide Oxide Dioxide
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C1 4.5 ALTERNATIVE FUELS
These are renewable fuels ? sources of energy
that could replace fossil fuels (coal, oil
gas)
BIODIESEL ETHANOL HYDROGEN
Less harmful to animals Breaks down 5 quicker Reduces particulates Making it produces other useful products CO2 neutral plants grown to create it absorb the same amount of CO2 generated when its burnt Easily made by fermenting sugar cane Gives off CO2 but the sugar cane it comes from absorbs CO2 when growing Very clean no CO2 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
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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 Posit
ive Test Unsaturated Bromine ? COLOURLESS
hydrocarbon Water
ALKENES Negative Test Saturated
Bromine ? NO RECTION Hydrocarbon Water
(orange) ALKANES

• CRACKING PROCESS
• Heat hydrocarbons to a high temp then either
• Mix them with steam OR
• Pass the over a hot catalyst

• EXAMPLE OF CRACKING
• Cracking is a thermal decomposition reaction
• C10H22 C5H12 C3H6 C2H4
• ALKENES
• These are unsaturated hydrocarbons
• They contain a double bond
• Have the general formula ? CnH2n

800oC
Decane
Pentane
Propene
Ethene
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C1 5.2 POLYMERS FROM ALKENES
PLASTICS ? Are made from lots of monomers joined
together to make a polymer
MONOMERS
POLYMER
Poly(ethene)
Ethene

• 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

n represent a large repeating number
Simplified way of writing it
n
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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

SMART POLYMERS ? Have their properties changed by
light, temperature or other changes in their
surroundings

• Light-Sensitive Plasters
• Top layer of plaster peeled back
• Lower layer now exposed to light
• Adhesive loses stickiness
• Peels easily off the skin

• 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

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C1 5.4 PLASTIC WASTE

• NON-BIODEGRADABLE
• Dont 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 resourcesBUT
• 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 100s 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

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C1 5.5 ETHANOL
There are 2 main ways to make ethanol

• 2) ETHENE
• Hydration reaction ? water is added
• Ethene Steam ? Ethanol
• C2H4 H2O ? C2H5OH
• 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
• CO2 is given off

• USES FOR ETHANOL
• Alcohol
• Perfume
• Rocket Fuel
• Solvents
• Antiseptic wipes

A molecule of ethanol
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C1 6.1 EXTRACTING VEGETABLE OIL
There are 2 ways to extract vegetable oils from
plants

• 2) DISTILLATION
• Plants are put into water and boiled
• Oil and water evaporate together
• Oil is collected by condensing (cooling the gas
  vapours)
• Lavender oil is one oil extracted this way

• 1) PRESSING
• Farmers collect seeds from plants
• Seeds are crushed and pressed
• This extracts oil from them
• Impurities are removed
• 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 (CC) ?
  they decolourise Bromine water

Food Energy (kJ)
Veg Oil 3900
Sugar 1700
Meat 1100
Table for info only dont memorise it!
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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

Margarine

• 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 bondsCC ? C-C
• Now called a HYDROGENATED OIL
• Reaction occurs at 60oC with a nickel catalyst

Double bonds converted to single bonds
60oC Nickel catalyst
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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
• Mayonnaise
• Milk
• Ice cream
• Cosmetics face cream, lipstick etc
• Paint

• EMULSIFIERS
• Stop water and oil separating out into layers
• Emulsifiers have 2 parts that make them work
• Hydrophobic tail is attracted to oil
• Hydrophilic head is attracted to water. It has
  a negative charge

-
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C1 6.4 FOOD ISSUES

• 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 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!

E.g. chocolate!
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C1 7.1 STRUCTURE OF THE EARTH
Atmosphere Most lies within 10km of the
surface Rest is within 100km but its 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!
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C1 7.2 THE RESTLESS EARTH
MOVING CONTINENTS The Earths 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
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C1 7.3 THE EARTHS ATMOSPHERE IN THE PAST
PHASE 2Green Plants, Bacteria Algae Oxygen
PHASE 1Volcanoes Steam CO2
PHASE 3Ozone Layer Animals Us

• Green plants, bacteria and algae ran riot in the
  oceans!
• Green plants steadily converted CO2 into O2 by
  the process of photosynthesis
• Nitrogen released by denitrifying bacteria
• Plants colonise the land. Oxygen levels steadily
  increase

• Volcanoes kept erupting giving out Steam and CO2
• The early atmosphere was nearly all CO2
• The earth cooled and water vapour condensed to
  form the oceans

• The build up of O2 killed off early organisms -
  allowing evolution of complex organisms
• The O2 created the Ozone layer (O3) which blocks
  harmful UV rays from the sun
• Virtually no CO2 left

Like this for a billion years!
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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
• Molecules for life (amino acids) came on
  meteorites from out of space
• Actual living organisms themselves arrived on
  meteorites
• Biological molecules were released from deep
  ocean vents

The experiment completed by Miller and Urey
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C1 7.5 GASES IN THE ATMOSPHERE

• THE ATMOSPHERE TODAY
• The main gases in the atmosphere today are

• 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
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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 CO2
• Rocks store CO2 and release it when burnt

CO2 LEVELSHave increased in the atmosphere
recently largely due to the amount of fossil
fuels we now burn
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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
C1 Products from oil
Here is an example of cracking
800C Catalyst C10H22 ----------------------gt
C5H12 C3H6 C2H4 Decane
Pentane Propene
Ethene
Ethene Propene (C2H4)
(C3H6)
Alkenes are produced during cracking. These are
unsaturated hydrocarbons which means they contain
a double bond. Their general formula is CnH2n
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.
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.
Polymerisation of ethene can represented like
this
Smart polymers like shape memory polymers, change
shape when they are hot or cold. Stitches that
tighten due to the bodys 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.
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----------gtethanol carbon
dioxide The ethanol is produced in batches and
gives off CO2, 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 CO2 and is a
continuous process. However, ethene comes from
crude oil, which means it is a non-renewable
production method.
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___________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
_______
C1 Products from oil
Here is an example of cracking
800C Catalyst C10H22 ----------------------gt
C5H12 C2H4 Decane
_______
Propene ______
Ethene (C2H4)

_______ are produced during cracking. These are
__________ hydrocarbons which means they contain
a ________ bond. Their general formula is _______
__________ 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
___________.
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
________.
Polymerisation of ethene can represented like
this
_______polymers like ________ _______polymers,
change shape when they are hot or cold. Stitches
that tighten due to the bodys ___________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.
___________ 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----------gtethanol carbon
dioxide The ethanol is produced in ______and
gives off CO2, 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.
40
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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

An atom is made up of a tiny nucleus with
electrons around it

• 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

42
C1 1.2 ATOMIC STRUCTURE

• Atoms contain PROTONS, NEUTRONS ELECTRONS
• Protons and Neutrons are found in the NUCLEUS
• Electrons orbit the nucleus

PARTICLE RELATIVE CHARGE RELATIVE MASS
Proton 1 (positive) 1
Neutron 0 (neutral) 1
Electron -1 (negative) 0
Any atom contains equal numbers of protons and
electrons

• 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

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

High energy shell
This is how we draw atoms and their electrons
Low energy shell
Sodium

• 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

44
C1 1.4 FORMING BONDS

• Atoms can react to form compounds in a number of
  ways
• Transferring electrons ? IONIC BONDING
• 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. MgCl2
• We have 2 chloride ions for every magnesium ion

45
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
• CaCO3 ? CaO CO2

• 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

Ca 1 C 1 O 3
Ca 1 C 1 O 3
H2 O2 ? H2O Add a 2 to the products
side to make the oxygen balance H2 O2 ?
2H2O This has changed the number of hydrogen
atoms so we must now adjust the reactant
side 2H2 O2 ? 2H2O
MAKING EQUATIONS BALANCEEquations MUST
balance We can ONLY add BIG numbers to the front
of a substance We can tell elements within a
compound by BIG letters CaCO3 ? this is a
compound made of 3 elements (calcium, carbon and
oxygen)
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 CaCO3
• 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 CaCO3 ?
CaO CO2
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
• CaCO3 2HCl ? CaCl2 H2O CO2

• TESTING FOR CO2
• We use limewater to test for CO2
• 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 MgCO3 ? MgO CO2
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
Step 4 Add CO2 Ca(OH)2 CO2 ? CaCO3 H2O
Step 1 Add Heat CaCO3 ? CaO CO2
Limestone
Calcium Oxide
Calcium Hydroxide Solution
Step 2 Add a bit of water CaO H2O ? Ca(OH)2
Step 3 Add more water filter Ca(OH0)2 H2O
? Ca(OH)2 (aq)
Calcium Hydroxide
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 its 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 its 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
  elementsThere are a number of types of steel
  alloys
• Carbon steels
• Low-alloy steels
• High-alloy steels
• Stainless steels

52
C1 3.3 ALUMINIUM TITANIUM
Aluminium Titanium
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 ORESThese contain lots of copper.
  There are 2 ways to consider1. Smelting
• 80 of copper is produced this way
• Heat copper ore strongly in a furnace with air
• Copper Oxygen ? Copper
  SulphurSulphide
  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 ORESThese contain smaller
  amount of copper. There are 2 main ways1.
  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
  copper2. 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
• Water pipes easily bent into shape, strong,
  doesnt react with water
• 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 its trickier as
  its 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
General formula for an alkane is CnH(2n2)
Methane CH4
Ethane C2H6
Propane C3H8
Butane C4H10
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

• Particulates
• Tiny solid particles
• Contain carbon and unburnt hydrocarbon
• Carried in the air
• Damage cells in our lungs
• Cause cancer

• Sulphur Dioxide
• Poisonous gas
• Its 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

59
C1 4.4 CLEANER FUELS
Burning fuels releases pollutants that spread
throughout the atmosphere

• 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

• CATALYTIC CONVERTERS
• Reduces the carbon monoxide and nitrogen oxide
  produced
• They are expensive
• They dont reduce the amount of CO2

Carbon Nitrogen ? Carbon
NitrogenMonoxide Oxide Dioxide
60
C1 4.5 ALTERNATIVE FUELS
These are renewable fuels ? sources of energy
that could replace fossil fuels (coal, oil
gas)
BIODIESEL ETHANOL HYDROGEN
Less harmful to animals Breaks down 5 quicker Reduces particulates Making it produces other useful products CO2 neutral plants grown to create it absorb the same amount of CO2 generated when its burnt Easily made by fermenting sugar cane Gives off CO2 but the sugar cane it comes from absorbs CO2 when growing Very clean no CO2 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 Posit
ive Test Unsaturated Bromine ? COLOURLESS
hydrocarbon Water
ALKENES Negative Test Saturated
Bromine ? NO RECTION Hydrocarbon Water
(orange) ALKANES

• CRACKING PROCESS
• Heat hydrocarbons to a high temp then either
• Mix them with steam OR
• Pass the over a hot catalyst

• EXAMPLE OF CRACKING
• Cracking is a thermal decomposition reaction
• C10H22 C5H12 C3H6 C2H4
• ALKENES
• These are unsaturated hydrocarbons
• They contain a double bond
• Have the general formula ? CnH2n

800oC
Decane
Pentane
Propene
Ethene
62
C1 5.2 POLYMERS FROM ALKENES
PLASTICS ? Are made from lots of monomers joined
together to make a polymer
MONOMERS
POLYMER
Poly(ethene)
Ethene

• 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

n represent a large repeating number
Simplified way of writing it
n
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

SMART POLYMERS ? Have their properties changed by
light, temperature or other changes in their
surroundings

• Light-Sensitive Plasters
• Top layer of plaster peeled back
• Lower layer now exposed to light
• Adhesive loses stickiness
• Peels easily off the skin

• 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
• Dont 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 resourcesBUT
• 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 100s 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
• C2H4 H2O ? C2H5OH
• 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
• CO2 is given off

• USES FOR ETHANOL
• Alcohol
• Perfume
• Rocket Fuel
• Solvents
• Antiseptic wipes

A molecule of ethanol
66
C1 6.1 EXTRACTING VEGETABLE OIL
There are 2 ways to extract vegetable oils from
plants

• 2) DISTILLATION
• Plants are put into water and boiled
• Oil and water evaporate together
• Oil is collected by condensing (cooling the gas
  vapours)
• Lavender oil is one oil extracted this way

• 1) PRESSING
• Farmers collect seeds from plants
• Seeds are crushed and pressed
• This extracts oil from them
• Impurities are removed
• 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 (CC) ?
  they decolourise Bromine water

Food Energy (kJ)
Veg Oil 3900
Sugar 1700
Meat 1100
Table for info only dont 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

Margarine

• 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 bondsCC ? C-C
• Now called a HYDROGENATED OIL
• Reaction occurs at 60oC with a nickel catalyst

Double bonds converted to single bonds
60oC Nickel catalyst
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
• Mayonnaise
• Milk
• Ice cream
• Cosmetics face cream, lipstick etc
• Paint

• EMULSIFIERS
• Stop water and oil separating out into layers
• Emulsifiers have 2 parts that make them work
• Hydrophobic tail is attracted to oil
• Hydrophilic head is attracted to water. It has
  a negative charge

-
69
C1 6.4 FOOD ISSUES

• 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 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!

E.g. chocolate!
70
C1 7.1 STRUCTURE OF THE EARTH
Atmosphere Most lies within 10km of the
surface Rest is within 100km but its 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 Earths 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 EARTHS ATMOSPHERE IN THE PAST
PHASE 2Green Plants, Bacteria Algae Oxygen
PHASE 1Volcanoes Steam CO2
PHASE 3Ozone Layer Animals Us

• Green plants, bacteria and algae ran riot in the
  oceans!
• Green plants steadily converted CO2 into O2 by
  the process of photosynthesis
• Nitrogen released by denitrifying bacteria
• Plants colonise the land. Oxygen levels steadily
  increase

• Volcanoes kept erupting giving out Steam and CO2
• The early atmosphere was nearly all CO2
• The earth cooled and water vapour condensed to
  form the oceans

• The build up of O2 killed off early organisms -
  allowing evolution of complex organisms
• The O2 created the Ozone layer (O3) which blocks
  harmful UV rays from the sun
• Virtually no CO2 left

Like this for a billion years!
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
• Molecules for life (amino acids) came on
  meteorites from out of space
• Actual living organisms themselves arrived on
  meteorites
• 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

• CARBON DIOXIDE
• Taken in by plants during photosynthesis
• When plants and animals die carbon is
  transferred to rocks
• Some