IGCSE
CHEMISTRY
NOTES
Unit 1-20
1
2
Unit 12
The Periodic Table
12.1
In the periodic table,
Periods are ………………………………………………………………………….……………………..
Groups or families are …………………………………………………………...……………………….
The inner transition elements are written separately at the bottom of the periodic table.
Lanthanides (57-71) are rare earth metals.
Actinides (90-103) are rare metals and most are radioactive.
In the same group, elements have …………………………………………, ……………….……….
……………………………………………, ……………………………………………….……………….
Across a period, melting point ……………………….. from group I to IV and then ……………….
until group 0 because the structure is changed from ……………..………… to …….……………. to
……………………………………
The group number in the periodic table shows the ……………………………………… of the
atom of the element.
The period number indicates ……………………………………………………. in the atom of the
element.
Group I =
Group II =
Group III =
Group IV =
Group V =
Group VI =
Group VII =
Group 0 =
200
12.2
Group I elements (…………………. metals)
Li (2.1)
Na (2.8.1)
K (2.8.8.1)
Rb (2.8.18.8.1)
Cs (2.8.18.18.8.1)
Fr (2.8.18.32.18.8.1)
Physical properties

……………………. elements that can readily react with air and water so they are stored
in ……………….…….

……………….. melting and boiling points and ……………… density metals

very ……………… so it can easily cut with a knife

…………… and …………… when freshly cut, but …………….. within a second an
exposure to air
Trends in group:

From top to bottom, melting and boiling points ………….. and density and reactivity
…………………….

Q
the metals get ………………… down the group
Explain why the reactivity of alkali metals (Li, Na, K) increases down the group in terms of
electron structure.
201
Chemical Properties
1
react with cold water to produce ……………………………… and ………………… gas
Metal + cold water
Observations for reaction with cold water
Lithium
Sodium
Fizzes slowly with
Disappears
Move slowly on
Remains solid no
Produces a
a few bubbles
slowly
the surface
flames
little heat
Fizzes quickly
Disappears
Move quickly on
Melts into a liquid
Produces
with many
quickly
the surface
ball,
more heat
bubbles
Potassium
no flames
Fizzes violently
Disappears very
Move very quickly
Melts into a liquid
Produces a
even many
quickly
on the surface
ball,
lot of heat
bubbles
lilac flame
Rubidium
Caesium
202
2
reacts with halogen gas to form ……………………….
Metal + Halogen
3
reacts rapidly with air to form coatings of the metal oxide.
Metal + Oxygen
Group 1 oxides are mostly ……………… in water to form ………………..…………………….
203
12.3
Group VII non-metallic elements (……………………)
F (2.7)
Cl (2.8.7)
Br (2.8.18.7)
I (2.8.18.18.7)
At (2.8.18.32.18.7)

non-metallic elements with ……………………….. molecules;

……………… valence electrons in the outermost shell;

gain ……………. electron from a metal to form an ionic compound
Physical properties
Halogen
Colour
Halogen
F2 gas at RT
I2 solid at RT
Cl2 gas at RT
I2 gas
Cl2 solution
I2 solution
Cl- solution
I - solution
Br2 liquid at RT
At2 solid at RT
Colour
Br2 gas
Br2 solution
Br - solution

………………. melting and boiling points;

………………………..conductors of heat and electricity ;

………………………… and ………………… vapours;

as …………………. Agents
204
Trends in group:

From top to bottom, melting and boiling points ………………….. as the intermolecular
forces get ……………………….

Therefore, the states slowly change from ……………….. to ……………….
to…………………………

From top to bottom, reactivity and oxidising ability ………………… and colour
becomes …………..
Q
Explain why the reactivity of halogens (Cl, Br, I) decreases down the group in terms of
electron structure.
Chemical Properties
1
react with ……………… to produce ……………….
2
react with hydrogen to form …………………………………….., steamy, acidic, poisonous
gases that are covalently bonded and are very soluble in water to produce …………………..
205
3
displace with other halogens according to their reactivity
4
react with other compound acting as an …………………. agent
206
12.4
Group 0 element (……………………………………………………………………….……………)
He (2)
Ne (2.8)
Ar (2.8.8)
Kr (2.8.18.8)
Xe (2.8.18.18.8)
Rn (2.8.18.32.18.8)
Physical properties

……………………. and …………………. gases at room temperature

They have ………………………….. electrons with …………………………………..
Trends in a group:

From top to bottom, the density ……………….. as the atom get heavier

the melting and boiling point ……………………... because the attractions between gas
particles get stronger as the atoms get ……………….. So, more energy is needed to
break the stronger attraction.
Chemical properties
They are unreactive gases. So they do not form stable ions and do not produce ionic
compounds.
They are reluctant to form covalent compounds because they have full electrons in outer shell.
Uses
He
-
filling in weather balloons, advertisement balloons and air ship
Ne
-
in making advertising lights,
Ar
-
filling in light bulbs to prevent oxidation of filament,
Kr/Xe -
in lamps and in light houses and photographic flash units
Rn
as radioactive element
-
207
12.5
Transition metals

metallic elements that are found in the central block of the Periodic Table (between
Group II and III)

……………. melting and boiling points, …………. density than other metals

much …………… reactive than other metals and so they do not react as rapidly with
air or water

has ……………………………. oxidation states or valencies

form ………………… compounds with other element

…………………. and …………………………………………can be used as
…………………. due to lack of reactivity.

form …………..……………………….
208
209
210
Unit 13
Metals and Reactivity Series
13.1
Alloys
An alloy is ……………………..………………………………………………………………
Some alloys contain non-metallic elements like carbon to harden a metal.
Types of alloys
Alloy
Constituents
Uses
Brass
Electrical plugs, musical instruments
Bronze
Trophies
Mild steel
Car and ship bodies, machinery parts
Stainless steel
Cutlery, surgical instruments, chemical
plants
Comparison of pure metals and alloys
Pure metal
Structure
Hardness
A lattice of positive ions in a sea
of mobile electrons
Soft and easily bent
Alloy
Atoms of different elements are
mixed together in disorderly
arrangement.
Strong and hard, not easily bent
Atoms cannot slide over each
Compressibility
Atoms can slide over each other
easily as atoms are of same size.
other easily as foreign atoms are
of different sizes and disrupt the
orderly arrangement of metal
atoms.
Diagram
Reasons for making
alloy
211
13.2
The metal reactivity series
212
Reactions of metals with water and dilute acid
Metal
Reaction with water
Reaction with dilute acid
(HCl or H2SO4)
K
Na
Li
Ca
Mg
Al
Zn
Fe
Pb
Cu
Ag
Au
Note:
1
Aluminium is a reactive metal but the initial reaction with dilute hydrochloric acid is slow
because it oxidized with air to form unreactive layer of aluminium oxide on its
surface.
2
Reactions for lead with dilute hydrochloric acid and sulfuric acid stop due to the formation
of insoluble lead salts.
3
Copper does not react with dilute hydrochloric acid and sulfuric acid but it reacts with dilute
or concentrated nitric acid to produce nitrogen oxides gases.
213
K (s)
+
H2O (l)
Na (s) +
H2O (l)
Ca (s) +
H2O (l)
Mg (s) +
H2O (g)
Al (s)
+ H2O (g)
Zn (s)
+ H2O (g)
Fe (s)
+ H2O (g)
Mg (s) + HCl (aq)
Al(s)
+ HCl (aq)
Zn (s)
+
HCl (aq)
Fe (s) + H2SO4 (aq)
Pb (s) + H2SO4 (aq)
214
13.3
Displacement reactions of metals from metal oxides or salt solutions
More reactive metal displaces less reactive metals from its compounds.
(1) Mg (s) +
(2) Cu (s) +
CuO (s)
MgO (s)
(3) Zn (s) +
CuSO4 (aq)
(4) Cu (s) +
ZnSO4 (aq)
(5) Cu (s) +
AgNO3 (aq)
(6) Ag (s) +
Cu(NO3)2 (aq)
215
Thermit reaction (reaction between aluminium and iron (III) oxide powder)
A mixture of aluminium powder and iron (III) oxide is put into a cone of filter paper. This is placed in
a bucket of sand. The magnesium fuse is lit.
A vigorous reaction occurs with flames, light and smoke. The result is a lump of iron where the
mixture was.
Observations:
Uses of thermite reaction:
216
217
218
219
220
221
Unit 14
Metal Extraction
14.1
Metals from their ores
An ore is ……………………………………………………………………………………………….
Minerals are compounds that occur naturally in the Earth; rocks are made up of different
minerals.
Most ores are ………….……….. , ………………………………. and ………………………….
The most abundant element in the Earth’s crust is …………..……….
The most abundant metal in the Earth’s crust is ………………………
Different types of ores
Iron ores
Aluminium ore
Zinc ores
Sulfide ores
Details of extraction
Concentration of ore:
In this metallurgical operation, the ore is concentrated by removing impurities like soil etc.
The process involves the crushing and washing of ore.
Calcination or Roasting of ore:
The concentrated ore is now heated in the presence of air. The process of roasting is
performed to remove moisture, CO2, impurities of sulphur.
Reduction of ore
The process of reduction is carried out in a blast furnace.
222
Extraction of zinc using a blast furnace
Zinc is extracted from either zinc blende ore (zinc sulphide) or calamine ore (zinc carbonate).
1
The zinc sulphide ore is ………………………………….. to give impure zinc oxide.
Zinc sulphide is ………………………………………………………………………………………
………………………………………………………………………………………………………….
The calamine is ………………………… into zinc oxide on …………………………………..
Calamine (zinc carbonate) is ………………………………………………………………………...
…………………………………………………………………………………………………………..
2
The impure zinc oxide can be treated in the blast furnace:
223
Raw materials
(Function)
(1)
(2)
(3)
1
A blast of air is blown into the bottom of the furnace. The excess carbon reacts with oxygen
in the air to form carbon monoxide:
Type of reaction:
2
Higher up the furnace carbon monoxide reduces zinc oxide to zinc.
Type of reaction:
The carbon dioxide formed can react with more carbon to reform carbon monoxide.
Type of reaction:
Some zinc oxide may also react directly with the carbon.
Type of reaction:

Zinc vapour passes out of the furnace and is cooled and condensed on a condensing
tray together with lead.

The impure zinc is then fractionally distilled from the mixture of slag and other metals
like lead and cadmium.

The slag and lead form two layers which can be tapped off at the base of the furnace.

The zinc can be further purified by dissolving it in dilute sulphuric acid and purified
electrolytically as described below.
224
Uses of Zinc
14.2
Extraction of iron using a blast furnace
Raw materials
(Function)
(1)
(2)
(3)
(4)
1
Formation of carbon dioxide
Coke is impure carbon and it burns in the hot air blast to form carbon dioxide. This is a strongly
exothermic reaction.
Type of reaction:
225
2
Formation of carbon monoxide
The carbon dioxide is reduced by more carbon to give carbon monoxide in the furnace at high
temperature.
Type of reaction:
3
Formation of molten iron in the furnace
It is the carbon monoxide which is the main reducing agent in the furnace-especially in the
cooler parts.
Type of reaction:
Some of iron oxide is also reduced by carbon itself in the hotter parts of the furnace.
Type of reaction:
4
Removing impurities with lime stone
Limestone is decomposed into calcium oxide and carbon dioxide by absorbing heat from
the furnace.
Type of reaction:
No excess limestone is used to remove impurities because it makes to cool the furnace by
absorbing heat energy.
226
Calcium oxide (basic oxide) reacts with main impurities, silicon dioxide (acidic oxide) by
neutralising each other to form calcium silicate (slag).
Type of reaction:
The slag formed float on the molten iron that can be tapped off separately.
The impurities (SiO2) must be removed from the furnace because it clogs the furnace with
solid material.
227
14.3
Iron into steel
Steel can be made from molten iron (95% pure) by removing impurities such as carbon, silicon,
sulfur and phosphorus in a basic oxygen converter (steel making furnace).
Impurities make the iron very brittle and pure iron also rusts very easily.
Fig: A basic oxygen converter
The converter is tipped to one side and molten iron and scrap iron are poured in. The
converter is put back into a vertical position.
A water–cooled tube (oxygen lance) is lowered into the converter.
Raw materials
(1)
(2)
(3)
228
1
Adding oxygen to form oxides:
Oxygen and powdered calcium oxide are blown onto the surface of the molten iron through
the lance.
The oxygen oxidises carbon, sulfur, silicon and phosphorus to their oxides.
Type of reaction:
The carbon dioxide and sulfur dioxide escape from the converter because they are gases.
These reactions are very exothermic that keeps the iron molten.
2
Adding calcium oxide to remove solid oxides:
Silicon and phosphorus oxides are solid acidic oxides that are removed from the converter
by reacting with powdered calcium oxide which is basic. A slag is formed that floats on the
surface of the molten iron and removed.
Type of reaction:
The amount of carbon in steel is controlled by the amount of oxygen blown into the pure iron.
The longer the oxygen blast the more carbon is removed.
After the required amount of carbon has been removed, other elements such as chromium
and nickel are added to make particular types of steel.
Various types of steel can be made by removing different amount of impurities.
229
14.4 Properties and uses of the different types of iron
Types of iron
Pig iron
Uses
Properties
-
-
Solidify molten iron
Cast iron
Impure iron
gear box, engine bolck
with 4% C
easily mould,
cheaper than steel
Mild steel
car bodies, parts of machinery,
(low carbon steel)
building
High-carbon steel
Tools such as hammers and chisels
harder, more brittle
Bicycle chains,
hard, not stretch much
high speed tools
high melting point
Low alloy steel
with 1% - 5% of Ni, Cr, Mn
and Ti
Stainless steel
Cutlery, surgical instruments,
with 20%chromium and 10%
construction pipes and
nickel
towers in chemical factories
soft, malleable,
very strong, resist corrosion
230
Properties and uses of other metal and alloy
Metal / alloy
Aluminium
Zinc
Copper
Uses
Properties

Air craft bodies

Food containers and cooking foil

Overhead wire cables

Galvanized steel

Making alloy

Electrical wiring

Making alloy

Cooking utensils
Recycling metals
Advantages
Disadvantages
conserve metal ores and other raw materials
collecting and storing metals may be costly
save energy because less fuel
take time and energy to collect waste metals
(extracting and purifying metals uses a lot of
energy)
reduces pollution arising from extracting and
so there may be more lorries and noise on the
purifying materials
roads of towns and villages
saves land that may be used for extracting ores
take time and money to sort out the metals from the
mixture of metals
reduces waste and problems of disposal of
unwanted material, eg. less landfill
231