Download The Big book of C1 chemistry

The Little Book of everything I need to know
for Chemistry
C1
Targets and test record
page
2
Topic checklists and key words
C1.1 Fundamental Ideas in Chemistry
C1.2 Limestone and Building Materials
C1.3 Metals and their Uses
C1.4 Crude Oil and Fuels
C1.5 Other Useful Substances from Crude Oil
C1.6 Plant Oils and their Uses
C1.7 Changes in the Earth and its Atmosphere
4
7
10
13
16
19
21
Command words for GCSE
How Science works key words
24
26
Basic Standards of Presentation and Marking
Laboratory Rules
Notes
28
29
30
Data sheet [inside back cover]
Periodic table [back cover]
31
32



Challenge grade: Date:………………… Grade: ………… Date:……………………Grade:..……
Topic
Test result Comment
C1.1 Fundamental ideas
C1.2 Limestone and building
materials
C1.3 Metals and their uses
C1.4 Crude oil and fuels
C1.5 Other useful substances from
crude oil
C1.6 Plant oils and their uses
C1.7 Changes and the Earth and its
atmosphere
Targets
Due by
2
Done?
Targets
Due by
3
Done?
Topic checklist – C1.1 The fundamental ideas in Chemistry
Atoms and elements are the building blocks of chemistry. Atoms contain protons, neutrons and
electrons. When elements react they produce compounds.
  
C1.1.1 Atoms
All substances are made of atoms.
An element is a substance that is made of only one sort of atom.
There are about 100 different elements. Elements are shown in the periodic table.
The groups (vertical columns) contain elements with similar properties.
Metals appear on the left hand side of the Periodic Table and non-metals on the right hand
side
Atoms of each element are represented by a chemical symbol, eg O represents an atom of
oxygen, and Na represents an atom of sodium.
Atoms have a small central nucleus, which is made up of protons and neutrons and around
which there are electrons.
The sub-atomic particles are as shown:
Name of particle
Charge
Proton
Neutron
Electron
+1
0
–1
Relative
mass
1
1
1
/1840
In an atom, the number of electrons is equal to the number of protons in the nucleus. Atoms
have no overall electrical charge.
All atoms of a particular element have the same number of protons. Atoms of different
elements have different numbers of protons.
The number of protons in an atom of an element is its atomic number. The sum of the protons
and neutrons in an atom is its mass number.
Mass number
no. protons: 35
80
Br
no.
neutrons:
(80-35)
= 45
35
Atomic number
no. electrons: 35 (same number as the atomic number)
4
Electrons occupy particular energy levels. Each electron in an atom is at a particular energy
level (in a particular shell). The electrons in an atom occupy the lowest available energy levels
(innermost available shells).
The electronic structure of the first 20 elements of the periodic table can be represented in the
following forms:
and
sodium : 2,8,1
C1.1.2 The periodic table
Elements in the same group in the periodic table have the same number of electrons in their
highest energy level (outer electrons) and this gives them similar chemical properties.
e.g. Na: 2,8,1 and K: 2,8,8,1
The elements in Group 0 of the periodic table are called the noble gases. They are unreactive
because their atoms have stable arrangements of electrons; they have eight electrons in their
outer energy level, except for helium, which has only two electrons i.e. full outer shells. E.g.
Ne:2,8
C1.1.3 Chemical reactions
When elements react, their atoms join with other atoms to form compounds. This involves
giving, taking or sharing electrons to form ions or molecules.



Compounds formed from metals and non-metals consist of ions;
metals lose electrons to form positive ions, whereas
non-metals gain electrons to form negative ions..


Compounds formed from non-metals consist of molecules.
In molecules the atoms are held together by covalent bonds.
Chemical reactions can be represented by word equations or by symbol equations.
No atoms are lost or made during a chemical reaction so the mass of the products equals the
mass of the reactants.
Notes:
5
C1.1 Fundamental ideas (atomic structure) key words:
Word / Phrase
Meaning
Atom
The smallest part of an element that can still be recognised as that
element.
Atomic number
The number of protons in (the nucleus of) an atom.
Compound
Substance containing atoms of two or more different elements
chemically joined together.
Covalent bond
Type of chemical bond in molecules [see C2]
Electron
Smallest sub-atomic atomic particle. Electrons have a charge of -1 and a
tiny mass (1/1840 amu); they orbit the nucleus of an atom in electron
shells.
Electron shell [energy level]
Area around a nucleus in which an electron is found
Electronic structure [electron
arrangement]
The arrangement of electrons in their shells [energy levels]. E.g. the
electronic structure for sodium is 2,8,1
Element
Substance containing only one type of atom
Energy level
See electron shell
Group
Vertical column of elements in the Periodic Table
Ion
Charged particle formed by the gain or loss of (outer shell) electrons
Mass number
The total number of protons and neutrons in the nucleus of an atom.
Molecule
Group of atoms held together by covalent bonds
Neutron
Subatomic particle found in the nucleus of an atom. Neutrons have no
charge and a mass of 1 amu
Noble gases
Unreactive group of elements found in group 0 of the Periodic Table.
Nucleus
Dense, central part of an atom that contains the protons and neutrons
Periodic table
Arrangement of elements in order of their atomic numbers
Proton
Subatomic particle found in the nucleus of an atom. Neutrons have a
charge of +1 and a mass of 1 amu
Sub-atomic particles
Small particles that make up an atom.
6
Topic checklist – C1.2 Limestone and building materials
Rocks provide essential building materials. Limestone is a naturally occurring resource that
provides a starting point for the manufacture of cement and concrete.
  
C1.2.1 Calcium carbonate
Limestone, mainly composed of the compound calcium carbonate (CaCO3), is quarried and
can be used as a building material.
Calcium carbonate can be decomposed by heating (thermal decomposition) to make calcium
oxide and carbon dioxide.
heat
Calcium carbonate
CaCO3
calcium oxide + carbon dioxide
CaO
+
CO2
The carbonates of magnesium, copper, zinc, calcium and sodium decompose on heating in a
similar way.
Some carbonates, such as potassium carbonate, do not decompose at Bunsen temperature
Calcium oxide reacts with water to produce calcium hydroxide, which is an alkali that can be
used in the neutralisation of acids.
Calcium oxide
CaO
+
+
water
H2O
calcium hydroxide
Ca(OH)2
A solution of calcium hydroxide in water (limewater) reacts with carbon dioxide to produce
calcium carbonate. Limewater is used as a test for carbon dioxide. Carbon dioxide turns
limewater cloudy.
Calcium hydroxide + carbon dioxide
Ca(OH)2
+
CO2
calcium carbonate + water
CaCO3
+ H2O
Carbonates react with acids to produce carbon dioxide, a salt and water.
CARBONATE + ACID
SALT + WATER + CARBON DIOXIDE
e.g. zinc carbonate + nitric acid
ZnCO3
+ 2HNO3
zinc nitrate + water + carbon dioxide
Zn(NO3)2 + H2O + CO2
Limestone is damaged by acid rain.

Limestone is heated with clay to make cement.
heat
Limestone

clay
cement
Cement is mixed with sand to make mortar and
Cement

+
+
sand
mortar
[used to hold bricks together]
Cement is mixed with sand and aggregate to make concrete.
Cement + sand + aggregate
concrete
7
[used for paving slabs,
building blocks]
LIMESTONE + CLAY
HEAT
CEMENT
+ SAND
+ SAND + AGGREGATE
MORTAR
CONCRETE
limestone is needed for buildings; the positive benefits of using this material must be
compared with the negative aspects of quarrying.
evaluate the environmental, social and economic effects of exploiting limestone and
producing building materials from it
Environmental
Social
Economic
pros
End of quarry life
beautification
Improved infrastructure e.g.
road network
Increased business
More jobs
cons
Habitats destroyed
Increased dust
Increased traffic/noise
pollution
Tourism might suffer
evaluate the developments in using limestone, cement and concrete as building materials,
and their advantages and disadvantages over other materials
Notes:
8
C1.2 Limestone and building materials key words:
Word / Phrase
Meaning
Acid
Sour substance that can attack metal, clothing or skin. The chemical
opposite of an alkali. When dissolved in water, its solution has a pH less
than 7. [see also C2]
Aggregate
Small stones; crushed rock
Alkali
A solution with a pH greater than 7
Cement
A building material made by heating limestone and clay
Clay
A stiff, sticky earth used in making pottery
Concrete
A building material made by mixing cement, sand and aggregate with
water
Limestone
Rock containing mainly calcium carbonate
Mortar
Neutralisation
A building material used to bind bricks together. It is made by mixing
cement and sand with water.
Reaction in which an acid and an alkali cancel each other out [see also
C2]
Quarry
Extract stone for building
Thermal decomposition
The breakdown of a compound into simpler substances using heat
9
Topic checklist – C1.3 Metals and their uses
Metals are very useful in our everyday lives. Ores are naturally occurring rocks that provide an
economic starting point for the manufacture of metals. Iron ore is used to make iron and steel.
Copper can be easily extracted but copper-rich ores are becoming scarce so new methods of
extracting copper are being developed. Aluminium and titanium are useful metals but are
expensive to produce. Metals can be mixed together to make alloys.
  
C1.3.1 Extracting metals
Ores contain enough metal to make it economical to extract the metal. The economics of
extraction may change over time.
Metal ores are obtained by mining and that this may involve digging up and processing large
amounts of rock. After mining, ores may be concentrated before the metal is extracted and
purified.
Unreactive metals such as gold are found in the Earth as the metal itself but most metals are
found as compounds that require chemical reactions to extract the metal.
Metals that are less reactive than carbon can be extracted from their oxides by reduction with
carbon, for example iron oxide is reduced in the blast furnace to make iron.
[reduction is removal of oxygen]
Metals that are more reactive than carbon, such as aluminium, are extracted by electrolysis of
molten compounds. The use of large amounts of energy in the extraction of these metals
makes them expensive.
Copper can be extracted from copper-rich ores by heating the ores in a furnace (smelting).
The copper can be purified by electrolysis i.e. copper is extracted from its ores by chemical
processes that involve heat or electricity.
The supply of copper-rich ores is limited. Copper-rich ores are being depleted and traditional
mining and extraction have major environmental impacts.
New ways of extracting copper from low-grade ores are being researched to limit the
environmental impact of traditional mining. Copper can be extracted by phytomining, or by
bioleaching.
 phytomining uses plants to absorb metal compounds and that the plants are burned to
produce ash that contains the metal compounds
 bioleaching uses bacteria to produce leachate solutions that contain metal
compounds.
Copper can be obtained from solutions of copper salts by electrolysis or by displacement
using scrap iron.
During electrolysis positive ions move towards the negative electrode.
Aluminium and titanium cannot be extracted from their oxides by reduction with carbon.
Current methods of extraction are expensive because:
 there are many stages in the processes
 large amounts of energy are needed.
We should recycle metals because extracting them uses limited resources and is expensive
in terms of energy and effects on the environment.
evaluate the social, economic and environmental impacts of exploiting metal ores, of using
metals and of recycling metals
evaluate the benefits, drawbacks and risks of using metals as structural materials.
10
C1.3.2 Alloys
Iron from the blast furnace contains about 96% iron. The impurities make it brittle and so it
has limited uses. Blast furnace iron is used as cast iron because of its strength in
compression.
Most iron is converted into steels. Steels are alloys since they are mixtures of iron with
carbon. Some steels contain other metals. Alloys can be designed to have properties for
specific uses. Low-carbon steels are easily shaped, high-carbon steels are hard, and
stainless steels are resistant to corrosion.
Most metals in everyday use are alloys. Pure copper, gold, iron and aluminium are too soft for
many uses and so are mixed with small amounts of similar metals to make them harder for
everyday use.
C1.3.3 Properties and uses of metals
The elements in the central block of the periodic table are known as transition metals. Like
other metals they are good conductors of heat and electricity and can be bent or hammered
into shape. They are useful as structural materials and for making things that must allow heat
or electricity to pass through them easily.
Copper has properties that make it useful for electrical wiring and plumbing. Copper:
 is a good conductor of electricity and heat
 can be bent but is hard enough to be used to make pipes or tanks
 does not react with water.
Low density and resistance to corrosion make aluminium and titanium useful metals.
Notes:
11
C1.3 Metals and their uses key words:
Word / Phrase
Meaning
Alloy
A mixture of metals (and sometimes non-metal such as carbon)
Bioleaching
Method of extracting metals from ores using micro-organisms
Brittle
Easily broken/shattered when hit
Corrosion
Chemical reaction that wears away a metal
Density
Displacement
Amount of substance in a given volume
Low density - lightweight
Reaction in which one (more reactive) element takes the place of
another in a compound
Ductile
Can be drawn into wires
Electrode
Conductor through which an electric current enters or leaves an
electrolyte
Electrolysis
Breaking down a substance containing ions by passing an electric current
though it as a solution or when molten
Electrolyte
Substance that conducts electricity in solution as ions are free to move
Leachate
Solution of metal ions obtained in bioleaching
Malleable
Can be hammered into shape
Molten
Melted
Ore
Rock containing enough metal to make it economically worthwhile to
extract the metal
Phytomining
Method of extracting metals from ores using plants
Reduction
Loss or removal of oxygen
Smelting
Heating a metal ore in order to extract its metal
Steel
Alloy of iron with small amounts of carbon and other metals
Transition metal
Metal found in the middle block of the Periodic Table
12
Topic checklist – C1.4 Crude oil and fuels
Crude oil is derived from an ancient biomass found in rocks. Many useful materials can be
produced from crude oil. Crude oil can be fractionally distilled. Some of the fractions can be
used as fuels. Biofuels are produced from plant material. There are advantages and
disadvantages to their use as fuels. Fuels can come from renewable or non-renewable
resources.
  
C1.4.1 Crude oil
Crude oil is a mixture of a very large number of compounds.
A mixture consists of two or more elements or compounds not chemically combined together.
The chemical properties of each substance in the mixture are unchanged. It is possible to
separate the substances in a mixture by physical methods including distillation.
Most of the compounds in crude oil consist of molecules made up of hydrogen and carbon
atoms only (hydrocarbons). Most of these are saturated hydrocarbons called alkanes, which
have the general formula CnH2n+2.
C1.4.2 Hydrocarbons
Alkane molecules can be represented in the following forms:
 a molecular formula such as C2H6
 a displayed formula in which | represents a covalent bond
H
H
I
I
H –– C –– C –– H
I
I
H
H
in displayed structures — represents a covalent bond
The many hydrocarbons in crude oil may be separated into fractions, each of which contains
molecules with a similar number of carbon atoms, by evaporating the oil and allowing it to
condense at a number of different temperatures. This process is fractional distillation.
Some properties of hydrocarbons depend on the size of their molecules. These properties
influence how hydrocarbons are used as fuels.
As the hydrocarbon molecules get bigger:
 boiling points increase as the number of carbon atoms increases (decreases up the
fractionating column)
 viscosity increases as the number of carbon atoms increases (decreases up the
fractionating column)
 flammability decreases as the number of carbon atoms increases (increases up the
fractionating column)
know the names and formulae of individual alkanes methane, ethane, propane and butane.
13
C1.4.3 Hydrocarbon fuels
Most fuels, including coal, contain carbon and/or hydrogen and may also contain some sulfur.
The gases released into the atmosphere when a fuel burns may include carbon dioxide, water
(vapour), carbon monoxide, sulfur dioxide and oxides of nitrogen (formed at high
temperatures).
Solid particles (particulates) may also be released.
Solid particles may contain soot (carbon) and unburnt fuels.
The combustion of hydrocarbon fuels releases energy.
During combustion the carbon and hydrogen in the fuels are oxidised.
 Hydrogen is always completely oxidised to water.
 In complete combustion, the carbon is fully oxidised to carbon dioxide.
 In (incomplete) combustion, the carbon may be partially oxidised to carbon monoxide
or may not be oxidised at all and released as solid particles (soot).
oxides of nitrogen are formed at the high temperatures reached in an engine
Sulfur dioxide and oxides of nitrogen cause acid rain
carbon dioxide causes global warming
Carbon monoxide is toxic as it reduces the ability of blood to carry oxygen
Solid particles cause global dimming
Sulfur can be removed from fuels before they are burned, for example in vehicles. Sulfur
dioxide can be removed from the waste gases after combustion, for example in power
stations.
Biofuels, including biodiesel and ethanol, are produced from plant material. There are
economic, ethical and environmental issues surrounding their use.
evaluate the impact on the environment of burning hydrocarbon fuels
evaluate the social, economic and environmental impacts of the uses of fuels
evaluate developments in the production and uses of better fuels, for example ethanol and
hydrogen in terms of:
 use of renewable resources
 storage and use of the fuels
 their products of combustion.
evaluate the benefits, drawbacks and risks of using plant materials to produce fuels.
Notes:
14
C1.4 Crude oil and fuels key words:
Word / Phrase
Meaning
Acid rain
Rain that is acidic due to dissolved gases, such as suulfur dioude,
produced by burning fossil fuels.
Alkane
Saturated hydrocarbon
Biodiesel
Fuel for cars made from plants
Biofuel
A biofuel is a fuel whose energy is obtained through photosynthesis i.e. a
fuel derived from plants
Butane
Alkane with four carbon atoms, C4H10
Combustion
Burning
Condense
Change from vapour to liquid by cooling
Crude oil
Mixture of hydrocarbons
Displayed formula
Distillation
Chemical formula that shows all the atoms and all the bonds in a
molecule
Separation of a liquid from a mixture by evaporation followed by
condensation
Ethane
Alkane with two carbon atoms, C2H6
Evaporate
Turn from a liquid to a vapour
Fossil fuel
Fuels that contain carbon and hydrocarbons that are the remains of
plants and animals
Fractional distillation
Method of separating a mixture of liquids with different boiling points
Fraction
Mixture of hydrocarbons with similar boiling points separation from
crude oil
Fuel
Substance burned for energy
Global dimming
The reflection of sunlight by tiny solid particles in the air
Global warming
The increasing in the average temperature of the Earth
Hydrocarbon
Compound containing carbon and hydrogen only.
Methane
Alkane with one carbon atoms, CH4
Molecular formula
Chemical formula that shows the number of each type of atom in the
molecule
Oxidation
Gain of oxygen
Propane
Alkane with three carbon atoms, C3H8
Saturated (hydrocarbon)
A hydrocarbon that has only single covalent bonds
Viscosity
Resistance to flow
15
Topic checklist – C1.5 Other useful substances from crude oil.
Fractions from the distillation of crude oil can be broken down (cracked) to make smaller
molecules including unsaturated hydrocarbons such as ethene. Unsaturated hydrocarbons can
be used to make polymers and ethene can be used to make ethanol. Ethanol can also be made
by fermentation.
C1.5.1 Obtaining useful substances from crude oil
crude oil is used to produce fuels and chemicals; it is a limited resource
Hydrocarbons can be cracked to produce smaller, more useful molecules. This process
involves heating the hydrocarbons to vaporise them. The vapours are either passed over a
hot catalyst or mixed with steam and heated to a very high temperature so that thermal
decomposition reactions then occur
The products of cracking include alkanes and unsaturated hydrocarbons called alkenes.
e.g.
decane

octane
+
ethene
C10H22

C8H18
+
C2H4
Alkenes have the general formula CnH2n.
Unsaturated hydrocarbon molecules can be represented in the following forms:
 As a molecular formula such as C3H6
 As a displayed formula in which ‖ or ══ represents a double covalent bond
H
H
H
I
I
I
H –– C –– C  C
I
I
H
H
be able to recognise alkenes from their names or formulae
know the names of individual alkenes, ethene and propene.
ethene, C2H4
propene, C3H6
Alkenes react with bromine water, turning it from orange to colourless.
orange
colourless
Some of the products of cracking are useful as fuel.
16
  
C1.5.2 Polymers
Alkenes can be used to make polymers such as poly(ethene) and poly(propene). In these
reactions, many small molecules (monomers) join together to form very large molecules
(polymers). For example:
Polymers have many useful applications and new uses are being developed, for example:
new packaging materials, waterproof coatings for fabrics, dental polymers, wound dressings,
hydrogels, smart materials (including shape memory polymers).
Many polymers are not biodegradable, so they are not broken down by microbes and this can
lead to problems with waste disposal.
Plastic bags are being made from polymers and cornstarch so that they break down more
easily. Biodegradable plastics made from cornstarch have been developed.
evaluate the social, economic and environmental impacts of the uses, disposal and recycling
of polymers
C1.5.3 Ethanol
Ethanol can be produced by hydration of ethene with steam in the presence of a catalyst.
Ethene
+
water
ethanol
Ethanol can also be produced by fermentation with yeast, using renewable resources. This
can be represented by:
sugar  carbon dioxide + ethanol
evaluate the advantages and disadvantages of making ethanol from renewable and nonrenewable sources.
evaluate the social and economic advantages and disadvantages of using products from
crude oil as fuels or as raw materials for plastics and other chemicals
Notes:
17
C1.5 Other useful substances from crude oil key words:
Word / Phrase
Alkane
Alkene
Biodegradable
Bromine water
Catalyst
Cracking
Meaning
Saturated hydrocarbon [hydrocarbon containing only single covalent
bonds]
Unsaturated hydrocarbon [hydrocarbon containing a carbon=carbon
double covalent bond]
Can be broken down by microorganisms
Solution used to test for unsaturation (alkenes). Bromine water changes
from orange to colourless in the presence of an alkene, but remains
orange in the presence of saturated compounds
Substance used to speed up a reaction (often used so a reaction can take
place at a lower temperature)
Reaction sued to break down large hydrocarbon molecules into smaller,
more useful ones, by passing the hydrocarbon vapour over a hot
catalyst.
Ethanol
Alcohol used as a biofuel
Ethene
Alkene with two carbon atoms, C2H4
Fermentation
Reaction in which the enzymes in yeast turn glucose (sugar) into ethanol
and carbon dioxide
Hydration
Reaction in which water is chemically added to a compound
Hydrocarbon
Compound containing carbon and hydrogen only
Hydrogel
Polymer that can absorb many times its weight in water
Monomer
Small reactive molecules that join together to make long chain molecules
Non-renewable
Something that cannot be replaced once it is used up
Polymer
Very long chain molecule, made up of many repeating units
Polymerisation
The reaction in which many monomers join together to make long chains
Propene
Alkene with three carbon atoms, C3H6
Renewable
Something that can be replaced when it is used up
Shape memory polymer
An example of a smart material; can return to original shape if deformed,
on heating
Smart material
Material that changes in response to a change in its environment
Thermal decomposition
Breaking down a compound into simpler substances by heat
Unsaturated (hydrocarbon)
A hydrocarbon that contains a carbon=carbon double covalent bond
18
Topic checklist – C1.6 Plant oils and their uses
Many plants produce useful oils that can be converted into consumer products including
processed foods. Emulsions can be made and have a number of uses. Vegetable oils can be
hardened to make margarine. Biodiesel fuel can be produced from vegetable oils.
  
C1.6.1 Vegetable oils
Some fruits, seeds and nuts are rich in oils that can be extracted. The plant material is
crushed and the oil removed by pressing or in some cases by distillation. Water and other
impurities are removed
Vegetable oils are important foods and fuels as they provide a lot of energy. They also
provide us with nutrients.
Vegetable oils are high in unsaturated fats compared with saturated fats and so have possible
health benefits
Vegetable oils have higher boiling points than water and so can be used to cook foods at
higher temperatures than by boiling. This produces quicker cooking and different flavours but
increases the energy that the food releases when it is eaten
C1.6.2 Emulsions
Oils do not dissolve in water. They can be used to produce emulsions. Emulsions are thicker
than oil or water and have many uses that depend on their special properties. They provide
better texture, coating ability and appearance, for example in salad dressings, ice creams,
cosmetics and paints. Emulsifiers are added to make emulsions more stable.
Higher Tier
Emulsifiers have hydrophilic and hydrophobic properties.
C1.6.3 Saturated and unsaturated oils
Vegetable oils that are unsaturated contain double carbon–carbon bonds. These can be
detected by reacting with bromine water.
Higher Tier
Vegetable oils that are unsaturated can be hardened by reacting them with hydrogen in
the presence of a nickel catalyst at about 60 °C.
Hydrogen adds to the carbon–carbon double bonds. The hydrogenated oils have
higher
melting points so they are solids at room temperature, making them useful as spreads
and in cakes and pastries.
evaluate the effects of using vegetable oils in foods and the impacts on diet and health
evaluate the use, benefits, drawbacks and risks of emulsifiers in foods.
Notes:
19
C1.6 Plant oils and their uses key words:
Word / Phrase
Bromine water
Distillation
Meaning
Solution used to test for unsaturation (alkenes). Bromine water changes
from orange to colourless in the presence of an alkene, but remains
orange in the presence of saturated compounds
Separation of a liquid from a mixture by evaporation followed by
condensation
Emulsifier
A substance that helps keep immiscible liquids mixed in a single layer
Emulsion
A mixture of liquids that do not dissolve in each other
Hydrogenated oil*
Oil which has had hydrogen added to reduce the degree of unsaturation
in the hardening process to make margarine
Hydrophilic *
Water-loving; the hydrophilic part of an emulsifier is attracted to water
Hydrophobic *
Water-hating; the hydrophobic part of an emulsifier is a hydrocarbon tail
that is attracted to oil
Immiscible
Liquids that do not mix but form separate layers e.g. oil and water
Nutrient
Food needed for a healthy diet
Saturated fat
Fat molecule with single carbon-carbon covalent bonds
Unsaturated fat
Fat molecule with some double carbon=carbon covalent bonds
20
Topic checklist – C1.7 Changes in the Earth and its atmosphere
The Earth and its atmosphere provide everything we need. The Earth has a layered structure. The
surface of the Earth and its atmosphere have changed since the Earth was formed and are still
changing. The atmosphere has been much the same for the last 200 million years and provides the
conditions needed for life on Earth. Recently, human activities have resulted in further changes in the
atmosphere. There is more than one theory about how life was formed.
  
Recognise that the Earth’s crust, the atmosphere and the oceans are the only source of
minerals and other resources that humans need
C1.7.1 The Earth’s crust
The Earth consists of a core, mantle and crust, and is surrounded by the atmosphere
The Earth’s crust and the upper part of the mantle are cracked into a number of large pieces
(tectonic plates).
The mantle is mostly solid, but it is able to move slowly.
Convection currents within the Earth’s mantle driven by heat released by natural radioactive
processes cause the plates to move at relative speeds of a few centimetres per year.
The movements can be sudden and disastrous. Earthquakes and / or volcanic eruptions
occur at the boundaries between tectonic plates.
explain why scientists cannot accurately predict when earthquakes and volcanic eruptions will
occur
Scientists once thought that the features of the Earth’s surface were the result of the shrinking
of the crust as the Earth cooled down following its formation.
explain why Wegener’s theory of crustal movement (continental drift) was not generally
accepted for many years
C1.7.2 The Earth’s atmosphere
For 200 million years, the proportions of different gases in the atmosphere have been much
the same as they are today:
 about four-fifths (80%) nitrogen
 about one-fifth (20%) oxygen
 small proportions of various other gases, including carbon dioxide, water vapour and
noble gases.
During the first billion years of the Earth’s existence there was intense volcanic activity. This
activity released the gases that formed the early atmosphere and water vapour that
condensed to form the oceans.
There are several theories about how the atmosphere was formed. One theory suggests that
during this period the Earth’s atmosphere was mainly carbon dioxide and there would have
been little or no oxygen gas (like the atmospheres of Mars and Venus today). There may also
have been water vapour and small proportions of methane and ammonia.
explain and evaluate theories of the changes that have occurred and are occurring in the
Earth’s atmosphere. No knowledge of other theories is required
There are many theories as to how life was formed billions of years ago.
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Higher Tier
One theory as to how life was formed involves the interaction between hydrocarbons,
ammonia and lightning. e.g. be aware of the Miller-Urey experiment and the ‘primordial
soup‘ theory, but remember this is not the only theory.
Higher Tier
Describe why we do not know how life was first formed.
Plants and algae produced the oxygen that is now in the atmosphere. Plants and algae
produce oxygen by a process called photosynthesis; this uses carbon dioxide from the
atmosphere.
Most of the carbon from the carbon dioxide in the air gradually became locked up in
sedimentary rocks as carbonates and fossil fuels.
 Carbon dioxide dissolves in the oceans
 Limestone was formed from the shells and skeletons of marine organisms.
 Fossil fuels contain carbon and hydrocarbons that are the remains of plants and
animals.
The oceans also act as a reservoir for carbon dioxide but increased amounts of carbon
dioxide absorbed by the oceans has an impact on the marine environment.
Nowadays the release of carbon dioxide by burning fossil fuels increases the level of carbon
dioxide in the atmosphere. This increase in carbon dioxide is thought to be causing global
warming
Higher Tier
Air is a mixture of gases with different boiling points and can be fractionally distilled to
provide a source of raw materials used in a variety of industrial processes.
Notes:
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C1.7 Changes in the Earth and atmosphere key words:
Word / Phrase
Meaning
Air
Mixture of gases
Algae
Simple plants, including seaweed
Atmosphere
Protective layer of gases surrounding the Earth
Continental drift
Theory that continents are able to move
Convection current
Circular motion caused by heating in liquids (hot liquids rise, causing
cooler, more dense liquid to fall)
Core
Centre of the Earth (the inner core is solid, the outer core is liquid)
Crust
Outer, solid layer of the Earth
Mantle
Layer of earth between the crust and the core
Marine organisms
Living things found in the sea
Miller-Urey*
Photosynthesis
Plate tectonics
Experiment designed to re-create the conditions in the early atmosphere
to see if life could have formed from the gases present
Process in which plants use sunlight to convert carbon dioxide and water
into sugar and oxygen
Theory describing the movement of the crust and upper part of the
mantle
Primordial soup
Mixture of organic molecules, such as amino acids, needed to start life
Sedimentary rock
Rock formed
Tectonic plate
Pieces of the crust and upper part of the mantle
* Higher tier
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Command words
For examples of how to answer these types of questions, see the separate booklet on Firefly.
Calculate
You should use numbers given in the question to work out the answer.
As stated on the front of the paper, you should always show their working, as it may be possible for the examiner
to award some marks for the method even if the final answer is wrong.
You should always give the units when asked to do so. In the question a mark can be awarded for the correct
unit/units, even if the calculation is wrong.
Compare
This requires you to describe the similarities and/or differences between things, not just write about one.
If you are asked to ‘compare x with y’, you need to write down something about x compared to y, using
comparative words such as ‘better, ‘more than’, ‘less than’, ‘quicker’, ‘more expensive’, ‘on the other hand.’
Complete
Answers should be written in the space provided, eg on a diagram, in spaces in a sentence or in a table.
Describe
You may be asked to recall some facts, events or process in an accurate way. For example you may be asked to
describe an experiment you have done, or you may need to give an account of what something looked like, or
what happened, eg a trend in some data.
Evaluate
You should use the information supplied as well as your knowledge and understanding to consider evidence for
and against. An evaluation goes further than ‘compare’. For example, you may be given a passage to read and
told to ‘Evaluate the benefits of using system x and system y’. This means you will need to write down some of
the points for and against both systems to develop an argument. A mark may also be available for a clear and
justified conclusion. For example, if a question is worth 5 marks, and does not specifically ask for a conclusion,
then you can gain all 5 marks for 5 valid points made for and against. If you only make 4 points but give a justified
conclusion then the 5th mark can be gained.
However, if a question specifically asks for a justified conclusion then full marks can only be gained if a justified
conclusion is given.
When giving comparisons you should be encouraged to compare both sides using linking words. For example in a
physics question ‘Wind power is a renewable resource whereas fossil fuels are non-renewable.’ Useful words to
use could be ’however’, ‘whereas’ ‘but’ and ’on the other hand’.
No credit will be given just for giving the information stated directly from the question in either the comparisons
or in the conclusion. In the chemistry example a mark is given for ‘waste’ oils being able to be used whereas just
saying ‘vegetable’ oils can be used would not gain a mark.
Likewise there would be no mark for stating that biodiesel produces fewer carbon particles, but a mark is
awarded for linking this to less global dimming.
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Explain
You should make something clear, or state the reasons for something happening.
The answer should not be a simple list of reasons.
This means that points in the answer must be linked coherently and logically. Suitable linking words could be ‘so’,
‘therefore’, ‘because’, ‘due to’, ‘since’, ‘this means’ or ‘meaning that’.
All of the stages/steps in an explanation must be included to gain full marks.
State, give, name, write down
Only a short answer is required, not an explanation or a description. Often it can be answered with a single word,
phrase or sentence.
If the question asks you to state, give, or write down one (or two etc) examples, you should write down only the
specified number of answers, or you may not be given the mark for some correct examples given.
Suggest
This term is used in questions where you need to apply your knowledge and understanding to a new situation.
Often there may be more than one correct answer as you are expected to base your answers on scientific
knowledge and/or principles.
Useful words to use are ‘may’, ‘might’, ‘could’, and ‘I think that’.
Use the information in the passage/diagram/graph/table to…
The answer must be based on the information given in the question. Unless the information given in the question
is used, no marks can be given.
In some cases you might be asked to use your own knowledge and understanding and credit will be given.
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How Science Works Key Words
Word / Phrase
Accuracy
Calibration
Meaning
A measurement result is considered accurate if it is judged to be close to
the true value
Marking a scale on a measuring instrument. This involves establishing
the relationship between indications of a measuring instrument and
standard or reference quantity values, which must be applied. For
example, placing a thermometer in melting ice to see whether it reads
zero, in order to check if it has been calibrated correctly
Data
Information, either qualitative or quantitative, that has been collected
Errors
See also uncertainties
- measurement error
The difference between a measured value and the true value
- anomalies
- random error
- systematic error
- zero error
These are values in a set of results which are judged not to be part of the
variation caused by random uncertainty.
These cause readings to be spread about the true value, due to results
varying in an unpredictable way from one measurement to the next.
Random errors are present when any measurement is made, and cannot
be corrected. The effect of random errors can be reduced by making
more measurements and calculating a new mean.
These cause readings to differ from the true value by a consistent
amount each time a measurement is made. Sources of systematic error
can include the environment, methods of observation or instruments
used. Systematic errors cannot be dealt with by simple repeats. If a
systematic error is suspected, the data collection should be repeated
using a different technique or a different set of equipment, and the
results compared
Any indication that a measuring system gives a false reading when the
true value of a measured quantity is zero, eg the needle on an ammeter
failing to return to zero when no current flows. A zero error may result in
a systematic uncertainty
Evidence
Data which has been shown to be valid
Fair test
A fair test is one in which only the independent variable has been
allowed to affect the dependent variable.
Hypothesis
A proposal intended to explain certain facts or observations
Interval
Precision
Prediction
Range
Repeatable
The quantity between readings, eg a set of 11 readings equally spaced
over a distance of 1 metre would give an interval of 10 centimetres.
Precise measurements are ones in which there is very little spread about
the mean value. Precision depends only on the extent of random errors –
it gives no indication of how close results are to the true value.
A prediction is a statement suggesting what will happen in the future,
based on observation, experience or a hypothesis.
The maximum and minimum values of the independent or dependent
variables; important in ensuring that any pattern is detected. For
example a range of distances may be quoted as either: "From 10cm to 50
cm" or "From 50 cm to 10 cm"
A measurement is repeatable if the original experimenter repeats the
investigation using same method and equipment and obtains the same
results
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Reproducible
Resolution
Sketch graph
True value
Uncertainty
Validity
Valid conclusion
Variables
- categoric
- continuous
- control
- dependent
- independent
A measurement is reproducible if the investigation is repeated by
another person, or by using different equipment or techniques, and the
same results are obtained.
This is the smallest change in the quantity being measured (input) of a
measuring instrument that gives a perceptible change in the reading.
A line graph, not necessarily on a grid, that shows the general shape of
the relationship between two variables. It will not have any points
plotted and although the axes should be labelled they may not be scaled
This is the value that would be obtained in an ideal measurement
The interval within which the true value can be expected to lie, with a
given level of confidence or probability, eg “the temperature is 20 °C ± 2
°C, at a level of confidence of 95 %.
Suitability of the investigative procedure to answer the question being
asked. For example, an investigation to find out if the rate of a chemical
reaction depended upon the concentration of one of the reactants
would not be a valid procedure if the temperature of the reactants was
not controlled.
A conclusion supported by valid data, obtained from an appropriate
experimental design and based on sound reasoning.
These are physical, chemical or biological quantities or characteristics
Categoric variables have values that are labels. Eg names of plants or
types of material
Continuous variables can have values (called a quantity) that can be
given a magnitude either by counting (as in the case of the number of
shrimp) or by measurement (eg light intensity, flow rate etc).
A control variable is one which may, in addition to the independent
variable, affect the outcome of the investigation and therefore has to be
kept constant or at least monitored.
The dependent variable is the variable of which the value is measured
for each and every change in the independent variable
The independent variable is the variable for which values are changed or
selected by the investigator
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Basic Standards of Presentation and Marking
Presentation
 All work is to have a title describing what it is about (not just ‘Prep ‘or ‘Classwork’).
 All work is to be dated.
 Headings and dates are to be underlined with a ruler in the same colour as the writing ink
used.
 A line space is to be left after the heading and date.
 Tippex or other correcting fluid must not be used; a neat, single straight line through the
incorrect word is all that is required.
Spelling
 Key spelling errors will be identified and the correct spelling written out by your teacher
for guidance.
 Science text books contain spelling lists of essential vocabulary.
Diagrams
 These need to be drawn in pencil.
 Any shading is to be done neatly using coloured pencils, if appropriate.
 Labeling should be done in ink.
 Labeling and headings must be able to be read while looking at the diagram and without
having to turn the paper.
 If arrows or lines are needed to connect the labels with the diagram, they should be
drawn in pencil with a ruler.
Graphs and tables
 All graphs and tables are to be drawn in pencil.
 Tables are to be titled and boxed in, have the independent variable in the first column
and only have units in the headings.
 Graphs are to be titled and have the independent variable along the x axis.
 Axes should be labeled and have units e.g. Time (seconds)
 Bar charts are to be used for discontinuous data, while line graphs are to be used for
continuous data.
Technical writing errors
The following indicators are used:
 sp and the underlining of a misspelling
 p to indicate incorrect or missing punctuation
 exp to indicate inaccurate expression with a wiggly line under the relevant area, or down
the margin.
 gr to indicate an area of inaccurate grammar, with a wiggly line under the relevant area,
or down the margin.
 ^ to show where a word, phrase or key point is missing.
Target setting
 T or
indicates a target for you to work on in future pieces of work.
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RHS Chemistry Department - Laboratory Rules
The Health and Safety at Work Act holds teachers and pupils responsible for their actions if others are harmed by them.
The biggest danger in the laboratory is YOU!
You are a danger whenever you are either thoughtless or careless or both.
Remember this, because the person most likely to suffer from your mistakes is YOU!
1.
You should only go into a lab if you have permission to do so from a teacher.
2.
You must wear eye protection when told to do so and at all times during Chemistry practical
work and keep it on until all practical work (including tidying up) is finished.
3.
Long hair must be tied back and loose garments should be tucked in before any experiment.
4.
Never put anything in your mouth (food or drink) in the lab. This includes fingers and pencils.
5.
You must not be seated during experimental work, unless you are specifically told to do so by
your teacher.
6.
If you are not sure of what you are supposed to do during a practical ASK for help.
7.
Don't touch apparatus, electrical equipment or chemicals (or gas taps, water taps and
electricity supplies) unless you have been told to do so.
8.
When heating substances, use small amounts and take care not to point test tubes at yourself
or anybody else, and never look directly down a test tube.
9.
Only place hot objects on a heat proof mat using appropriate apparatus. Allow hot equipment
or substances to cool before you touch them, store them or throw them away.
10. If you get burnt, or get chemicals on your skin, immediately wash the affected part with lots of
cold water and alert your teacher.
11. Report ANY accident, however slight (including breakages and spillages), to your teacher.
12. Waste, or surplus, materials should be disposed of as instructed by your teacher.
DON'T throw solids into sinks.
13. Keep your bench clean and tidy. Make sure it is wiped clean at the end of any experiment.
14. Wash your hands after laboratory work; this is especially important before meals.
15. Apparatus and chemicals must NEVER be removed from a lab.
ANY INAPPROPRIATE OR DANGEROUS BEHAVIOUR WILL
RESULT IN EXCLUSION FROM PRACTICAL ACTIVITIES.
I have read and understood the laboratory rules listed above.
Name:______________________________________________
Form: _______________
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Notes
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