C4 Key facts sheet
A: Atomic structure (Higher in bold)
Test Mark:
Key Fact
An atom has a nucleus surrounded by negative electrons.
The nucleus is made up of positive protons and neutral neutrons.
• electron charge –1 and mass 0.0005 (zero)
• proton charge +1 and mass 1
• neutron charge 0 and mass 1.
An atom is neutral because it has the same numbers of protons (positive) and
electrons (negative)
Atoms have a radius of about 10–10m and a mass of about 10–23g.
Isotopes are varieties of an element that have the same atomic number but different mass
numbers.
Identify isotopes from data about the number of electrons, protons and neutrons in
particles, using the information below
The atomic number (bottom number) is the number of protons in an atom.
The mass number (top number) is the total number of protons and neutrons in an atom.
Deduce the number of protons, electrons and neutrons in a particle
given its atomic number (bottom number – tells us number of
protons and electrons) and mass number (top number – tells us the
number of protons and the number of neutrons. To work out the
number of neutrons: mass number – atomic number)
Groups are vertical columns and periods are horizontal rows
Metals are found on the left hand side of the ‘steps’ that divide the periodic table and nonmetals are on the right
An element’s identity can be deduced from its electronic structure – the group tells us how
many electrons are in the outer shell and the period tells us how many shells an atom has.
Deduce the electronic structure of the first 20 elements in the periodic table eg
calcium is 2.8.8.2.
Hints and tips – the first shell can only hold 2 electrons and the rest can all hold a
maximum of 8 electrons
An element is made up of one type of atom. You can find it’s formulae in the periodic table.
Eg. Sodium = Na
A compound is two or more elements chemically bonded together. Its formula is made up
of the symbols of the elements it contains. Eg. Water = H2O
The model of the atom has changed:
• John Dalton described atoms as solid spheres and he thought each spheres made
up the different elements
• JJ Thompson concluded from his experiments that atoms were not solid. His
measurements of charge and mass showed that an atom must contain negative
particles = electrons. This theory was known as the ‘plum pudding’ model.
• Rutherford conducted the gold foil experiment, where they fired positively charged
atoms at gold and saw that a small number were reflected backwards and most
passed straight through the atom. This lead him to believe that there was a
positively charged nucleus at the centre and the rest of the atom was empty space.
• Bohr –proposed that electrons were held in shells that stopped them being drawn
into the positive nucleus.
• Unexpected results in these experiments have allowed scientists to use each other work
to lead to the current theory of a nuclear atom.
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C4 Key facts sheet
B: Ionic bonding (Higher in bold)
Test Mark:
Key Fact
An ion is a charged atom or group of atoms. You can recognise them from a positive or negative
sign eg. SO42Sodium chloride and magnesium oxide cannot conduct electricity in a solid, but can if molten liquid
or in a solution
When ionic compounds are molten (melted) or dissolved, the ions are free to move and
conduct electricity. These ions are in a fixed position in a solid and cannot move.
Sodium chloride has a lower melting point than magnesium oxide
Magnesium oxide is made from Mg2+ and O2- ions, which have double the charge of the ions
in sodium chloride (Na+ and Cl-) This means the attraction between the is harder to
overcome and requires more energy.
Atoms with a full outer shell of electrons have a stable electronic structure. (2 in first, 8 in the rest)
Metal atoms can lose electrons from their outer shells to form positive ions. They do this to achieve
a full and stable outer shell.
Non-metal atoms form negative ions by gaining electrons into their outer shells. They do this to
achieve a full and stable outer shell.
In ionic bonding, a metal and non-metal combine by transferring electrons to form positive ions and
negative ions which then attract one another.
When sodium chloride or magnesium oxide are formed by ionic bonding, they make a giant ionic
lattice in which positive ions are strongly attracted to negative ions
Explain, using the “dot and cross” model, the ionic bonding in simple binary compounds.
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C4 Key facts sheet
C: Covalent bonding (Higher in bold)
Test Mark:
Key Fact
There are two types of bonding:
• ionic bonding between metals and non-metals
• covalent bonding between non-metals.
Covalent compounds, such as carbon dioxide and water do not conduct electricity.
They cannot conduct electricity because they have no free moving electrons or ions
Covalent compounds, such as carbon dioxide and water, have low melting points.
Although the atoms have strong covalent between individual atoms, they have weak
intermolecular forces between molecules that do not require much energy to
overcome.
Describe a group of elements as all the elements in a vertical column of the periodic table
and that the
elements have similar chemical properties.
Describe a period of elements as all the elements in a horizontal row of the periodic table.
Describe the main stages in the development of the classification of elements:
• Dobereiner – organised elements into groups of three (triads) based on chemical
properties. The middle element had a relative atomic mass that was the average of the
other two.
• Newlands – Newland’s Octaves – he put elements into rows of seven, as he noticed that
every eighth element had similar properties. Problems: he left no gaps, the pattern didn’t
work for transition metals, some elements in the same groups didn’t have similar properties
and he mixed up metals and non metals.
• Mendeleev – placed elements into order of atomic mass and ensure that elements in
each group shared similar properties. He left gaps for new elements to be inserted in to the
periodic table when they were discovered. When these elements were discovered and
fitted the pattern of the group they were place in, it made other scientists respect his
version of the periodic table.
Explain how further evidence confirmed Mendeleev’s ideas about the periodic table:
• confirmation of his predictions about unknown elements
• how investigations on atomic structure (mass number and electronic structure)
agreed with his ideas
Classification of elements was provisional, based on evidence gathered at the time.
Explain, using the “dot and cross” model, the covalent bonding in simple binary
compounds or molecules containing single and double covalent bonds.
In covalent bonding, elements share electrons to gain a full outer shell of electrons
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C4 Key facts sheet
D: Group 1 elements (Higher in bold)
Test Mark:
Key Fact
Sodium (Na), lithium (Li) and potassium (K) are Group 1 elements.
Group 1 elements are known as the alkali metals because they form hydroxides when they
react with water, which is an alkali
Group 1 elements are stored under oil, because they react rapidly with water and oxygen in
the air. The oil prevents them from doing this.
When lithium, sodium and potassium react with water, the following observations are seen:
• hydrogen is formed and fizzing is heard
The metal floats and moves around on the top of the water
• an alkali is formed which is the hydroxide of the metal
• potassium gives a lilac flame.
Construct the word equation for the reaction of a Group 1 element with water:
______ + water  _____hydroxide + hydrogen
1. lithium + water  lithium hydroxide + hydrogen
2. Sodium + water  sodium hydroxide + hydrogen
3. potassium+ water  potassium hydroxide + hydrogen
Construct the balanced symbol equation for the reaction of a Group 1 element with
water:
1. 2Li + 2H2O 2LiOH + H2
2. 2Na + 2H2O 2NaOH + H2
3. 2K+ 2H2O 2KOH + H2
The reactivity of group 1 metals with water increases down Group 1
Group 1 metals get more reactive down the group, because they more easily lose
their electrons. (less attraction for the electron in the outer shell, due to it being
further from the nucleus and additional shielding)
Recall the flame test colours for:
Lithium compounds= red
Sodium compounds = orange
Potassium compounds = lilac
Group 1 elements have similar properties, because they all have one electron to
lose and all form positive ions with stable electronic structures.
The loss of electrons is known as oxidation. (OIL RIG = oxidation is loss, reduction is
gain)
Construct a balanced symbol equation to show the formation of group 1 ions:
Li  Li+ + eNa  Na+ + eK  K+ + e-
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C4 Key facts sheet
E: Group 7 elements (Higher in bold)
Test Mark:
Key Fact
The Group 7 elements are known as the halogens.
Fluorine, chlorine, bromine and iodine are Group 7 elements.
Uses of some Group 7 elements:
• chlorine is used to sterilise water
• chlorine is used to make pesticides and plastics
• iodine is used to sterilise wounds.
Group 7 elements react vigorously with Group 1 elements.
Eg. Sodium + chlorine  sodium chloride
Lithium + fluorine  lithium fluoride
Construct the balanced symbol equation for the reaction of a Group 1 element with a
Group 7 element
Eg. 2Na + Cl2  2NaCl
2Li + Br2  2LiBr
The reactivity of the Group 7 elements decreases down the group.
This is because it is harder for the elements to gain electrons, as the outer shell is
further from the positive nucleus
A more reactive group 7 element will displace a less reactive group 7 element from a
compound.
A Group 7 element and a metal halide can react in a displacement reaction:
Eg. Fluorine + sodium chloride  sodium fluoride + sodium
Construct balanced symbol equations for the reactions between Group 7 elements
and metal halides:
eg. Fl2 + 2NaCl  2NaF + Cl2
Fluorine (top of group 7) will be a gas, have a lower melting and boiling point and be
more reactive than the other halogens.
Astatine (bottom of group 7) will be a solid, have a higher melting and boiling point
and be less reactive than the other halogens.
Group 7 elements have similar properties, because they each gain an electron to form
negative ions with stable electronic structures.
Construct an equation to show the formation of a halide ion from a halogen molecule:
Eg. Cl +e-  ClBr +e-  BrI +e-  IThe gain of electrons is known as reduction. (OIL RIG = oxidation is loss, reduction is gain)
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C4 Key facts sheet
F: Transition metal elements (Higher in bold)
Test Mark:
Key Fact
Transition metal elements can be found in between group 2 and group 3, in the middle of
the periodic table
All transition elements are metals and have typical metallic properties. (high melting and
boiling points, strong, but malleable, high density, good conductors of heat and electricity)
Recall that copper (Cu) and iron (Fe) are transition elements
Thermal decomposition is a reaction in which a substance is broken down into at least two
other substances by heat.
Describe the thermal decomposition of carbonates of transition elements including FeCO3,
CuCO3, MnCO3 and ZnCO3:
• metal oxide formed
• carbon dioxide formed (bubbles seen)
• colour change occurs (colours not needed).
Construct word equations for thermal decomposition reactions:
Eg. Copper carbonate  copper oxide + carbon dioxide
Construct the balanced symbol equations for the thermal decomposition of:
• FeCO3  FeO + CO2
• CuCO3  CuO + CO2
• MnCO3 MnO + CO2
• ZnCO3 ZnO + CO2
The test for carbon dioxide is that it turns limewater milky
Precipitation reactions are between solutions that makes an insoluble solid. The solids are
called precipitates.
Recall that compounds of transition elements are often coloured:
• copper compounds are often blue
• iron(II) compounds are often light green
• iron(III) compounds are often orange/brown.
Sodium hydroxide solution can be used to identify the presence of transition metal ions in
solution:
• Cu2+ gives a blue solid
• Fe2+ gives a grey/green solid
• Fe3+ gives an orange/brown solid
• The solids are called precipitates.
Construct balanced symbol equations for the reactions between Cu2+, Fe2+ and Fe3+
with OH–:
Cu2+ + 2OH-  Cu(OH)2
Fe2+ + 2OH-  Fe(OH)2
Fe3+ + 3OH-  Fe(OH)3
Recall that transition elements and their compound are often used as catalysts:
• iron in the Haber process
• nickel in the manufacture of margarine
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C4 Key facts sheet
G: Metals structure and properties (Higher in bold)
Test Mark:
Key Fact
Iron is used to make cars and bridges because it is strong and cheap
Copper is used to make electrical wiring because it is a good conductor of electricity and
easily bent (malleable)
Suggest properties needed by a metal for a particular given use eg saucepan bases need
to be good conductors of heat.
List the physical properties of metals:
• lustrous, hard and high density
• high tensile strength
• high melting and boiling points
• good conductors of heat and electricity.
The particles in a metal are held together by metallic bonds.
Metallic bonding is the strong attraction between a sea of delocalised electrons and
close packed positive metal ions in fixed positions
Metals have high melting points and boiling points due to strong metallic bonds.
This is because there is a strong attraction between the delocalised electrons and
the positively charged fixed ions.
Metals conduct electricity as they have a sea of free moving (delocalised) electrons
that can carry the charge
At low temperatures some metals can be superconductors.
Normally, metals have some electrical resistance and whenever electricity flows through
them, they heat up and energy is waste, If you make metals cold enough, their resistance
disappears. These metals are known as superconductors.
The potential benefits of superconductors are:
• loss free power transmission
• super-fast electronic circuits
• powerful electromagnets.
The drawbacks of superconductor are:
• They only work at really low temperatures – this is difficult and expensive
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C4 Key facts sheet
H: purifying and testing water (Higher in bold)
Test Mark:
Key Fact
Different types of water resources found in the United Kingdom are:
• lakes
• rivers
• aquifers
• reservoirs
List some of the pollutants that may be found in domestic water supplies and say how they
got there
• nitrate residues – from excess fertiliser run off into rivers and lakes
• lead compounds – from old lead pipes
• pesticide residues –from spraying too near to rivers and lakes
The types of substances present in water before it is purified are:
• dissolved salts and minerals
• microbes
• pollutants
• insoluble materials
The water purification process includes:
1. Filtration – a wire mesh screens out large twigs and gravel and then sand bed filter
out any other smaller solid bits
2. Sedimentation – iron sulphate or aluminium is added to the water, which makes fine
particles clump together and settle at the bottom
3. Chlorination -chlorine is bubbled through the water to kill microbes/harmful bacteria
in water
The reactions of barium chloride with sulfates and silver nitrate with halides are examples
of precipitation reactions (an insoluble solid is made from two solutions)
Barium chloride solution is used to test for sulfate ions – it gives a white precipitate
Barium chloride(aq) + ______ sulphate(aq)  ______ chloride(aq) + barium sulphate(s)
BaCl2(aq) + ___SO4(aq)  ____Cl (aq) + BaSO4(s)
Silver nitrate solution is used to test for halide ions:
• chloride ions give a white precipitate
• bromide ions give a cream precipitate
• iodide ions give a pale yellow precipitate.
Silver nitrateaq) + ______ chloride(aq)  ______ nitrate aq) + silver chloride(s)
Silver nitrateaq) + ______ bromide(aq)  ______ nitrate aq) + silver bromide(s)
Silver nitrateaq) + ______ iodide(aq)  ______ nitrate aq) + silver iodide(s)
Construct balanced symbol equations for the reactions of silver nitrate with halides
given the appropriate formulae:
AgNO3(aq) + ___Cl(aq)  ____NO3(aq) + AgCl(s)
AgNO3(aq) + ___Braq)  ____NO3(aq) + AgBr(s)
AgNO3(aq) + ___I(aq)  ____NO3(aq) + Agl(s)
Some soluble substances are not removed from water during purification. This is
because they are dissolved in water and cannot be filtered out.
The disadvantages of using distillation of sea water to make large quantities of fresh
water is that it uses lots of energy and is very expensive.
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