Notesale: Turn your study into money

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C1 Chapter 1 Key Points

1
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Each element has its own unique symbol
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The chemical formula of a compound shows how many of each type of atom it
contains
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•
•
•
•
•

Metals lose electrons to form positive ions
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Metals and non-metals form ionic bonds together
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Atoms are conserved during chemical reactions – they just ‘change partners’
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1
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•
•
•
•
•

The electrons around an atom are arranged in energy levels (electron shells)
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The elements can be arranged in a periodic table in which elements with similar
properties occur in the same group
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Metals are found to the left of the table, non-metals to the right, divided by a zigzag line
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4
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•
•
•
•
•
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Group 1 contains very reactive metals
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Group 1 metals react violently with water, giving off hydrogen gas
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Helium is used for safe airships and for party balloons
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Neon is used in neon lights and as a very low temperature refrigerant
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1
• Many raw building materials come from rocks such as limestone
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2
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• Limestone and other carbonates react with acid to produce carbon dioxide, a salt and
water
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2
...

• Limestone (CaCO3) and other carbonates can be broken down by thermal
decomposition
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• If you add water to calcium oxide it forms calcium hydroxide, which can be used to
neutralise acid in the soil
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This is the
test for carbon dioxide
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4
• Limestone and clay are the raw materials of cement and concrete
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• Concrete is cheap and easy to store, mix and pour into moulds of any shape or size
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Chapter 1
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1
• Most metals are found in chemical compounds called ores
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• Metal ores are finite and are expensive to refine, so recycling metals makes economic
sense as well as having less impact on the environment than mining
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2
• Most metals are found as ores from which the metal must be extracted
...

• Less-reactive metals, such as copper, can be extracted by carbon reduction
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• Electrolysis on an industrial scale uses large amounts of electrical energy, so it is
expensive
...
3
• Blast furnaces have to run at very high temperatures to reduce iron oxide and melt the
iron
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• Acid is used to leach copper salts from ore, after which they are purified by electrolysis
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3
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• The developed world is taking more than its fair share of metal resources
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• New techniques such as phytomining can be used to reclaim waste land and get more
metals
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5
• Metals have many useful properties that we use in our everyday lives
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• Elements in the central block of the periodic table are called transition metals
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• Copper can be stretched into wire for electrical cables or formed into pipes for water
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• Titanium resists corrosion, so is ideal for nuclear reactor pipes or hip replacements
...
1
• Crude oil is mixture of a very large number of compounds
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e
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• Most of the hydrocarbons in crude oil are saturated compounds called alkanes
...
2
• Crude oil consists of a mixture of hydrocarbons, mostly alkanes
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• The larger an alkane’s molecules:
– the higher its boiling point
– the lower down the fractionating column its vapours condense
– the less easily it ignites or flows
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3
• Coal is mostly carbon
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They may also
contain some sulfur
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• Carbon monoxide, particulates, sulfur dioxide and oxides of nitrogen may be produced
when fuels burn incompletely
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4
• Carbon dioxide is a greenhouse gas that contributes to global warming
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• Sulfur dioxide is a cause of acid rain
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• Sulfur dioxide can be removed from the waste gases in power stations
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5
• Fossil fuels may well run out
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C1 Chapter 5 Key Points
5
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• Longer alkanes are cracked by being vaporised and passed over a hot catalyst
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• Alkenes are unsaturated hydrocarbons
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2
• Polymers are long-chain molecules made by joining lots of short molecules, called
monomers, together
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• Many different polymers with different properties are made by using different alkenes
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3
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5
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• The use of chemicals derived from crude oil has brought many advantages to our lives,
but it has also created problems for us to deal with as a society
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5
• Ethanol is used as a fuel, a solvent and in alcoholic drinks
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• Hydration of ethene is faster, is a continuous process and makes pure ethanol, but
fermentation uses less energy and uses renewable raw materials
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• These oils can be extracted by crushing the plant material, followed by pressing or
distillation
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• Vegetable oils can be used as fuels such as biodiesel
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2
• Emulsions are mixtures of oil and water
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• Emulsions are thicker than oil or water on their own
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C1 6
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• The amount of unsaturation can be measured using bromine water
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• The melting points of oils increase when they are hydrogenated
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4
• Vegetable oils are important in the diet because they provide energy and nutrients
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C1 Chapter 7 Key Points
• The Earth is made up of by a central core surrounded by the mantle and crust
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• Earthquakes and volcanoes occur at the boundaries between tectonic plates
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C1 7
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• His ideas were rejected at the time because there was no explanation for how the
continents could move
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C1 7
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It is about four-fifths nitrogen and one-fifth oxygen, plus
small amounts of other gases
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• The composition of air has remained roughly constant for about 200 million years
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4
• Scientists have several different theories about the early atmosphere and how it has
changed over time
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• The gases in the early atmosphere may have been released from volcanoes
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C1 7
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• The amount of carbon dioxide in the air has remained roughly constant for the last 200
million years because processes that release it into and remove it from the atmosphere
have been in balance
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• Increasing carbon dioxide in the air is lowering the pH of the oceans, affecting marine
life
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1
• Alchemists may have ‘experimented’ but John Dalton was one of the first true
chemists
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• Elements cannot be broken down into simpler substances as they are made from one
type of atom only
...

• Compounds are made when atoms of different elements chemically join together
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1
...

• Chemical reactions occur when other atoms try to achieve the stable ‘noble gas’
structure
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• Non-metals gain extra electrons to form negative ions with a stable electron
configuration
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1
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• The charges on ions need to balance in a neutral ionic compound
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1
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• The bonds holding the atoms together are called covalent bonds
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Most molecules are compounds
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• Carbon and silicon dioxide form giant covalent molecules
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5
• Metals have ‘loose’ outer electrons which give rise to their properties
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• Metals conduct heat and electricity because of their delocalised electrons
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KEY POINTS C2 Chapter 2 Structures
2
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• When substances made from molecules are melted or boiled, it is the weak forces
between molecules that are overcome; the covalent bonds themselves do not break
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• Substances made from simple molecules do not conduct electricity because molecules
are neutral
...
2
• Ionic compounds are made up of positive and negative ions in a giant lattice
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• Ionic compounds conduct electricity when molten or dissolved because the ions can
move
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3
• Diamond, graphite and silicon dioxide are examples of giant covalent substances
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• Giant covalent substances have high melting points due to the need to break covalent
bonds
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• Carbon can also form fullerenes which are molecules made of linked rings of carbon
atoms
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2
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• Metals can be bent and hammered into shape because the layers of atoms can slide
over each other
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• Alloys are mixtures of metals with other metals or other elements such as carbon
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• Shape memory alloys, such as nitinol, can return to their original shape after being
deformed
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5
• Polymers made from different monomers have different properties and uses
...

• Thermosetting polymers have cross-links between polymer chains, making them hard
and rigid
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• Thermosoftening polymers do not have cross-links and they soften and melt on heating
2
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• Nanoscience is the study of nanoparticles
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• There are many new and potential uses for nanoparticles
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1
• Atoms contain a central nucleus containing protons and neutrons, surrounded by
electrons in energy levels (shells)
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• The mass number of an atom equals the number of protons it contains, plus the
number of neutrons
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3
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• The mass of one mole of a substance equals the relative formula mass in grams
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3
• The mass of chemicals that react or are produced in a chemical reaction can be
calculated by finding reacting quantities in moles or by using mass ratios
...
4
• In practice, reactions do not give as much product as expected
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• The yield is less than 100% because:
– some reactants or products may be lost during the process
– other reactions may take place
– some reactions are reversible, meaning that the products can turn back into the
reactants
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5
• All substances have an empirical formula, but substances made of molecules have a
molecular formula as well
...

• The molecular formula of a compound gives the number of atoms of each element in
one molecule
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3
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• They allow us to identify substances and find how much there is
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• Gas chromatography is used to separate substances that take different times to pass
through a long column packed with a solid
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• A mass spectrometer is often used to identify substances separated in gas
chromatography
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Key Points C2

Chapter 4

Rates of Chemical Reactions

4
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• You can measure the rate of a reaction by seeing how the amount of either reactants
or products vary over time
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• As gases escape into the air, gas production can also be measured by mass loss in the
apparatus
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2
• For chemicals to react, their particles have to collide with enough energy to break the
existing bonds
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• At higher temperatures particles have more energy, so reactions usually go faster
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4
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• For gases, if you increase the pressure you increase the rate of reaction
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4
• Reactions involving solids take place at surfaces
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4
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• Catalysts work by lowering the activation energy needed for a reaction
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KEY POINTS C2 Chapter 5
5
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• Reactions that give out energy are called exothermic reactions
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5
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They are
called endothermic reactions
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• Electrolysis, splitting a compound apart using electricity, is also endothermic
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5
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• The amount of energy transferred is the same in each direction
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KEY POINTS C2 Chapter 6
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• The pH scale is a measure of the acidity or alkalinity of a solution
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6
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• In neutralisation reactions, H+ and OH– ions react together to produce water
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6
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• Soluble salts can also be made by reacting an acid with a metal, but some metals are
too reactive and some are not reactive enough
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6
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• Precipitation reactions are useful for treating effluent or water for drinking
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5
• Ammonia dissolves in water to produce an alkaline solution
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• Different methods are appropriate for making different salts
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1
• Electrolysis is the decomposition of an ionic substance into elements using an electric
current
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• Positively charged ions move to the negative electrode, gain electrons and are
reduced
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7
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• Oxygen is produced at the positive electrode unless halide ions are present
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7
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• Aluminium forms at the negative electrode and oxygen forms at the positive electrode
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7
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These are important materials for the chemical industry
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1
• Over the 19th century there were many attempts to find a pattern in the properties of
elements
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• Mendeleev allowed gaps for ‘undiscovered elements’ in his periodic table and made
predictions as to their properties, so the pattern held
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• The modern periodic table arranges the elements by proton number, not atomic mass
...
2
• The periodic table contains the elements arranged in order of their proton number
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• Elements in the same group have similar properties
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• The periodic table is a powerful tool for predicting how elements react
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1
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• Group 1 metals:
– react with water to give strongly alkaline solutions
– form single positive ions
– form colourless salts that dissolve in water
– get more reactive down the group
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1
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• Many transition metals and their compounds make excellent catalysts
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• As the atomic number increases along a row of transition elements, an inner energy
level is being filled with electrons
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5
• Group 7 contains the highly reactive non-metals called the halogens
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• Going down the group the melting and boiling points get higher
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• Going down the group the halogens become less reactive
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• More reactive halogens can displace less reactive halogens from their compounds
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1
• In some areas, water dissolves calcium and/or magnesium ions from the rocks
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• Hard water makes scum with soap; soft water lathers easily
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2
• Temporary hard water contains calcium or magnesium hydrogencarbonate
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• Permanent hard water contains calcium or magnesium sulfate, which cannot be
removed by boiling
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• Ion-exchange columns soften water by swapping sodium ions for the calcium and
magnesium ions
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3
• Water is safe to drink only if the levels of dissolved salts, other toxic substances and
microorganisms are kept below certain limits
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• Water quality can be improved by filtering it through activated carbon, silver or an ionexchange resin
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4
• Sea water cannot be drunk safely, as the salt level is far too high
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• Distillation is a way of purifying water
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• Hard water has several health benefits over soft water
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C3 KEY POINTS SHEET
3
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3
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• Energy level diagrams show these changes in energy as the reaction proceeds
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3
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• The difference between the energy absorbed and the energy released determines
whether a reaction is exothermic or endothermic
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4

• Hydrogen can be burned as a fuel or used in hydrogen-powered fuel cells
...
However, it is a very clean fuel, emitting only water
vapour when it is burned
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1
• Flame tests can be used to distinguish the Group 1 metal ions
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4
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• Sulfate ions are detected using barium chloride solution in the presence of dilute
hydrochloric acid
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4
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• Concentration is measured in g/dm3 or mole/dm3
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4
• Titrations can be used to find the amounts of acid or alkali in a solution
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C3 Chapter 5 Key Points
5
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• In a closed system, reversible reactions reach a state of equilibrium
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5
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• If the temperature is increased, the position of an equilibrium moves in the direction of
the endothermic reaction
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• If the pressure of an equilibrium involving gases is increased, the position of the
equilibrium moves towards the side with less gas molecules
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5
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• The reaction is slow and reversible
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• The temperature of 450 °C is a compromise between the rate of reaction and the yield
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• The reaction mixture is cooled to liquefy the ammonia, which is removed, and the
unreacted hydrogen and nitrogen are recycled
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C3 Chapter 6 Key Points
6
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• Methanol, ethanol and propanol are the first three alcohols in the series
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• Ethanol is the alcohol in alcoholic drinks
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• Alcohols react with sodium to form hydrogen
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• Alcohols are oxidised by air to form carboxylic acids
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2
• Carboxylic acids are a homologous series of organic compounds containing the
functional group –COOH
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• Ethanol is oxidised to ethanoic acid by microbes in air or mild oxidising agents
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• Carboxylic acids dissolve in water to form acidic solutions
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6
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• Esters can be made by the reaction of alcohols with carboxylic acids in the presence of
an acid catalyst
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