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Scheme of work – Cambridge International AS Level Physical Science (8780)
CHEMISTRY – SECTION II
Unit 3: Inorganic Chemistry
Recommended prior knowledge
Unit 1 (Theoretical Chemistry) and Unit 2 (Physical Chemistry) should have been studied before this unit. The unit builds on the ideas of atomic and molecular
structure and bonding developed in Unit 1, and those concerning enthalpy changes, equilibrium, kinetics and redox developed in Unit 2.
Context
This self-contained unit can be studied either before or after Unit 5 (Organic Chemistry) but must be studied before Unit 4 (Industrial processes).
Outline
The unit covers most of the Inorganic part of the course. Concepts developed in Units 1 and 2 (see prior knowledge above) are applied to Period 3 and Groups II
and VII of the Periodic Table, as well as to aspects of nitrogen and sulfur chemistry. It links with Unit 4 (Industrial processes).
Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
[Across Period 3] describe
qualitatively (and indicate the
periodicity in) the variations in
atomic radius, ionic radius,
melting point and electrical
conductivity of the elements (see
the Data Booklet)
Graphs could be plotted of atomic radius, ionic radius and melting point
from Na to Ar, (and also from Li to Ne), to show periodicity. Conductivity
increases from Na to Al, then falls to a low at Si, then zero for the rest.
Chemistry for Advanced Level 15.1-15.3
Advanced Chemistry 87
C7(b)
explain qualitatively the variation
in atomic radius and ionic radius
Increasing nuclear charge across a period pulls the electron shells in
more strongly and so more closely. In the same period anions contain
one more shell than cations.
C7(c)
interpret the variation in melting
point and in electrical conductivity
in terms of the presence of simple
Candidates should be able to:
C7(a)
v2 2Y07
site 4 (period 3)
site 7 (periodic trends)
site 17 (the periodic table)
Chemistry for Advanced Level 15.3
Advanced Chemistry 88
AS Level and A Level Chemistry 9.4 & 9.5
Melting point should be related to structure (see Sections C3(l) and
C3(m)). Conductivity should be related to (increasingly more)
Cambridge International AS Level Physical Science (8780)
1
Syllabus ref
Learning objectives
Suggested teaching activities
molecular, giant molecular or
metallic bonding in the elements
delocalised e- in Na-Al; conduction bands in Si; localised electrons in
covalent bonds for the rest.
A graphic illustration of the semiconduction of Si is showing the
increase in conduction on heating a block of Si over a Bunsen burner
(use a battery + bulb or ammeter circuit in a demonstration of this).
C7(d)
explain the variation in first
ionisation energy (see Section
C2)
See also section C2(e). Increasing nuclear charge and decreased
atomic radius (similar shielding) across the period causes a general
increase in the attraction between the nucleus and the outer electrons.
Hence, there is a general increase in ionisation energy across the
period. Slight decreases at Mg-Al, and P-S due to new p sub-shell
experiencing more shielding than the s subshell, and repulsion between
electrons sharing the same p orbital, respectively.
C7(e)
explain the variation in
electronegativity (see Section C3)
See also section C3(f). Increasing nuclear charge and decreased atomic
radius (similar shielding) across the period causes a general increase in
the attraction between the nucleus and the bonding electrons. Hence,
there is a general increase in electronegativity across the period.
C7(f)
describe the reactions, if any, of
the elements with
(i) oxygen (to give Na2O, MgO,
Al2O3, P4O10, SO2, SO3),
Na, Mg, Al, P and S should all be burned in gas jars filled with oxygen or
air. To avoid contamination by metallic combustion spoons, a good
technique with Na is to heat a small piece of Na on a dry brick with a
Bunsen until it starts to burn, and then to place over it an inverted gas jar
of O2. This also works with Cl2, producing a white powder of NaCl.
Comparison should be made between the violent reaction of sodium,
and the very slow reaction of magnesium, with water at room
temperature. Also, demonstrating the reaction of strongly heated
magnesium ribbon in steam illustrates the difference a change in
reaction condition can make. In all cases, hydrogen gas is produced but
at room temperature the product is the hydroxide. At elevated
temperatures, the oxide is formed.
Chemistry for Advanced Level 15.4-15.5
Advanced Chemistry 89
AS Level and A Level Chemistry 9.7
Teaching AS Practical Skills 17, 18, 19
Chemistry for Advanced Level 15.4
Advanced Chemistry 89
AS Level and A Level Chemistry 9.9
(ii) water (Na and Mg only)
C7(g)
describe the reactions of the
above oxides with water
[treatment of peroxides and
superoxides is not required]
Add universal indicator solution to the oxides prepared above. The trend
is from strong alkali (NaOH), through very weak alkali (Mg(OH)2) to
neutral (Al2O3 and SiO2) to acidic. Students should work out the full
balanced equations for all reactions.
C7(h)
describe and explain the
This could include some titrations, but also practical work on the
v2 2Y07
Cambridge AS Level Physical Science (8780)
Learning resources
AS Level and A Level Chemistry 9.6
site 3 (the nature of oxides)
site 16 (periodicity)
2
Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
acid/base behaviour of Period 3
oxides and hydroxides, including,
where relevant, amphoteric
behaviour in reaction with sodium
hydroxide (only) and acids
dissolving of MgO in acids, and the precipitation and redissolving of
Al(OH)3 in NaOH(aq). Sodium aluminate can be represented as either
NaAlO2 or NaAl(OH)4.
There is a trend in the bonding of the oxide/hydroxides from ionic to
covalent across the period. This trend should be used to explain the
trend in the nature of the oxides/hydroxides from basic to acidic across
the period.
C7(i)
interpret the variations and trends
described above in terms of
bonding and electronegativity
Chemistry for Advanced Level 15.1
Advanced Chemistry 88-89
AS Level and A Level Chemistry 9.12
C7(j)
suggest the types of chemical
bonding present in oxides from
observations of their chemical
and physical properties
Electropositive metals such as Na and Mg form ionically bonded oxides
which are basic in nature.
As the electronegativity of the element increases and becomes more
similar to that of O, covalently bonded oxides are formed, which are
acidic. Al is on the borderline – the structure of the solid is ionic but with
a large degree of polarisation, and the oxide is amphoteric.
These generalisation can be applied to the oxides of other elements
such as Ga, Ge, As.
C7(k)
predict the characteristic
properties of an element in a
given group by using knowledge
of chemical periodicity
Properties such as metallic or non-metallic; giant or simple covalent;
reactive or non-reactive; forming ionic or covalent oxides; melting point
and boiling point.
Chemistry for Advanced Level 15.1
Advanced Chemistry 89
AS Level and A Level Chemistry 9.14, 9.15
AS Level and A Level Chemistry 9.13
Similar generalisations to those above. Also include group trends –
metals becoming more reactive down their groups, but non-metals less
reactive.
C8(a)
C8(b)
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[For Group II] describe the
reactions of the elements with
oxygen and water
[For Group II] describe the
behaviour of the oxides with
water
The reactions become more vigorous as the Group is descended. Show
Mg ribbon reacting with steam and Mg powder reacting slowly with water
(the hydrogen can be collected using an inverted funnel + inverted test
tube). Calcium pieces will rise and sink when placed in cold water.
Hydrogen bubbles are formed and adhere to the surface of each piece
and, burst on reaching the surface of the water.
Chemistry for Advanced Level 16.1-16.2
Advanced Chemistry 93
AS Level and A Level Chemistry 10a.5
As the solubility of the hydroxides increases from Mg to Ba, so the
solutions formed become increasingly alkaline. The exothermicity of the
CaO + H2O reaction (the “slaking” of lime) should be demonstrated and
contrasted with the virtual non-reaction of MgO + H2O.
Chemistry for Advanced Level 16.2
Advanced Chemistry 93
AS Level and A Level Chemistry 10a.7
Teaching AS Practical Skills 20
Cambridge AS Level Physical Science (8780)
site 7 (periodic trends)
3
Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
C8(c)
[For Group II] describe the
thermal decomposition of the
nitrates and carbonates
Decomposition becomes more difficult down Group II, as the polarising
power of the cation decreases with increasing radius. Heating samples
of the (anhydrous) nitrates will show the relative ease of production of
NO2
Chemistry for Advanced Level 16.4
Advanced Chemistry 93
AS Level and A Level Chemistry 10a.8
Teaching AS Practical Skills 20
site 16 (periodicity)
Chemistry for Advanced Level 16.3-16.5
Advanced Chemistry 93
[For Group II] interpret, and make
predictions from, the trends in
physical and chemical properties
of the elements and their
compounds
Students should consider the properties discussed above. The m. pts.
and b. pts. of the elements show no trend, but atomic and ionic radii
increase. The m.pts. of the oxides decrease down the Group.
C8(e)
Describe the use of lime in
agriculture and in building
construction
Describe the production of CaO and Ca(OH)2 from CaCO3. Both CaCO3
and Ca(OH)2 are used to decrease the acidity of the soil, and hence to
enhance the uptake of essential cations by plants. Investigate local
sources of “garden lime” and find out whether it is CaCO3 or Ca(OH)2,
and what it is used for.
Students could search their local areas for examples of lime, as a
component of (Portland) cement, being used in the preparation of mortar
(in brick walls) and concrete. Examples may also be found of limestone
or marble being used in buildings or for statues.
C9(a)
[For Group VII] describe the
trends in volatility and colour of
chlorine, bromine and iodine
Chemistry for Advanced Level 17.1
Advanced Chemistry 101
AS Level and A Level Chemistry 12.1
C9(b)
Interpret the volatility of the
elements in terms of van der
Waals' forces
Deepening colour (from pale green to orange-brown to purple) is due to
the decreasing energy of the π - π* transition. While the origin of colour
is not part of this syllabus, more able students do tend to appreciate a
simple explanation. Prepare solutions of the halogens in hexane to
demonstrate these colours.
Increased van der Waals’ forces are due to the increasing number of
(polarisable) electrons in the clouds around the molecules.
C9(c)
describe the relative reactivity of
the Group VII elements as
oxidising agents
Practical examples could include X2 + NaBr, NaI etc.; X2 + Na2S2O3.
Other reactions include Cl2 + Fe (→ FeCl3) and I2 + Fe (→ FeI2). The
decreasing trend in oxidising power of the halogens could be linked to
the decrease in attraction, caused by increasing atomic radius down the
group, between the nucleus and electrons on other atoms. The concept
of electron affinity is not required.
Chemistry for Advanced Level 17.4
M 101
AS Level and A Level Chemistry 12.2
Teaching AS Practical Skills 21, 23
C8(d)
v2 2Y07
site 8 (Group II)
Cambridge AS Level Physical Science (8780)
4
Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
C9(d)
describe and explain the
reactions of halide ions with:
(i) aqueous silver ions followed
by aqueous ammonia,
(ii) concentrated sulfuric acid (to
illustrate the reductive
powers of the halide ions)
Practical work can involve preparing and noting the colours of AgX
(white, cream and yellow) and whether they dissolve or not in dil or conc
NH3. Equations (full or ionic) and complex formation (→ [Ag(NH3)2]+) will
not be required.
Simple acid-base reactions with F– (for discussion only) Cl– to give HCl
(a useful practical task). The increasing reductive powers of the halide
ions can be shown by the increasing ease of oxidation of X– to X2.
Reaction of concentrated sulfuric acid with Br– (→ SO2 as reduction
product of H2SO4), and with I– (→ H2S and SO2 as reduction products of
H2SO4).
Students should use oxidation numbers to construct balanced equations
for these reactions.
Chemistry for Advanced Level 17.3-17.4
Advanced Chemistry 101
AS Level and A Level Chemistry 12.5, 12.6
Teaching AS Practical Skills) 22
C9(e)
describe and interpret in terms of
changes of oxidation number the
reaction of chlorine with water
and with cold aqueous sodium
hydroxide
Introduce the idea of disproportionation. Students should use oxidation
numbers to construct balanced equations for these reactions.
Chemistry for Advanced Level 17.2, 17.4
Advanced Chemistry 101
AS Level and A Level Chemistry 12.7
C9(f)
recognise the industrial
importance and environmental
significance of the halogens and
their compounds, (e.g. for
bleaches; PVC; halogenated
hydrocarbons as solvents,
refrigerants and in aerosols and
in water purification) (see Section
C14)
Mention the discovery by atmospheric chemists of the problem caused
by CFCs in the ozone, O3, layer; and, the replacement of CFCs by
hydrocarbons and freons. The potential problems with the incineration
of PVC waste; the phasing-out of chlorinated solvents; DDT and BHC
residues in the environment. (see also C14 and C16). Internet searches
for other uses.
Chlorine is used as part of many water purification programmes. The
equilibrium for the reaction of water with chlorine, Cl2 + H2O = HCl +
HOCl, produces too great an acidity, so an alkali is added at the same
time. Students would find a visit the local waterworks of benefit.
Chemistry for Advanced Level 17.1
AS Level and A Level Chemistry 12.8,12.9
C10(a)
explain the lack of reactivity of
nitrogen
Mention that the strength of the N≡N bond affects both the kinetic
inertness (large Ea) and the thermodynamic stability. This should be
linked to the formation of NOx compounds found in car exhaust gases.
The spark on ignition, and the high temperature reached in the
combustion chambers, providing the energy required to cleave the N2
bond.
Advanced Chemistry 97
AS Level and A Level Chemistry 14.1
C10(b)
describe:
(See Section C11(d) for manufacturing details) NH3 as a Brønsted base.
Chemistry for Advanced Level 3.12, 6.3
v2 2Y07
Cambridge AS Level Physical Science (8780)
site 21a
5
Syllabus ref
C10(c)
Learning objectives
Suggested teaching activities
Learning resources
(i) the formation, and structure,
of the ammonium ion
(ii) the displacement of ammonia
from its salts
Neutralisation, titration. NH4+ isoelectronic with CH4, hence same
shape.
Warming with NaOH(aq) and testing for NH3 with moist red litmus paper
– a good test for NH4+. The fumes from a stopper of a bottle of
concentrated hydrochloric acid form a white smoke (NH4Cl) in the
presence of ammonia.
Advanced Chemistry 97
AS Level and A Level Chemistry 14.2
describe the Haber process for
the manufacture of ammonia from
its elements (see Section C11)
(See Section C11(d) for manufacturing details) Revise the conditions,
and the reasons for using them, the overall equation, and the main uses
of the ammonia produced.
Chemistry for Advanced Level 20.2
Advanced Chemistry 83
AS Level and A Level Chemistry 7a.7
site 16 (manufacture of ammonia)
C10(d)
recognise the environmental
consequences of the uncontrolled
use of nitrate fertilisers
Eutrophication of rivers and lakes, especially in areas of high rainfall,
due to algal blooms and subsequent decomposition using up dissolved
oxygen. Discuss local examples.
AS Level and A Level Chemistry 14.4
C10(e)
describe and explain the
occurrence, and catalytic
removal, of oxides of nitrogen
The production of NO from N2 + O2 in internal combustion engines (see
Section C10(a)). The role of Pt as a heterogeneous catalyst. Key
reactions that occur in the catalytic converter are NO + CO → ½N2 +
CO2;
CO + ½O2 → CO2; Complete combustion of hydrocarbon fuels. h/c +
O2→ CO2 + H2O.
Incomplete combustion of hydrocarbon fuels. h/c + O2→ CO + H2O
Chemistry for Advanced Level 15.4
AS Level and A Level Chemistry 14.5
C10(f)
describe the formation of
atmospheric sulfur dioxide from
the combustion of sulfur
contaminated carbonaceous fuels
In car engines and power stations. Sulfur containing compounds, e.g.
CH3SH, are present in crude oil and coal. They cannot be completely
removed by fractional distillation of crude oil. Suitable equations include
S + O2 → SO2; CH3SH + 3O2 → CO2 + 2H2O + SO2. The increasing use
of flue gas desulfurisation (FGD) in power stations, and low-sulfur road
fuels in cars and lorries.
AS Level and A Level Chemistry 14.6
C10(g)
state the role of sulfur dioxide in
the formation of acid-rain and
describe the main environmental
consequences of acid-rain .
SO2 + ½O2 + H2O → H2SO4. Catalysed by sunlight or NO2.
Damage to stonework and mortar on buildings; aggravation of asthma;
acidifying lakes and rivers. Investigate local examples.
Chemistry for Advanced Level 15.4
AS Level and A Level Chemistry 14.7
v2 2Y07
Cambridge AS Level Physical Science (8780)
6
Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
C10(h)
describe the Contact process for
sulfuric acid production (see
Sections C5 and C11)
(See Section C11(f) for production details.) Revise the conditions, and
the reasons for using them, the equations for each stage.
Chemistry for Advanced Level 20.2
Advanced Chemistry 83
AS Level and A Level Chemistry 7a.7, 14.8
v2 2Y07
Cambridge AS Level Physical Science (8780)
7