This is a summary of the topic "metals" in the GCE O levels subject: Chemistry. Students taking either the combined science (chemistry/physics) or pure chemistry will find this useful. These slides are prepared according to the learning outcomes required by the examinations board.

1. METALS

2. PROPERTIES OF
METALS

3. PROPERTIES OF METALS
Metals
Generally solids at room temperature
Good conductors of heat and electricity
Malleable and ductile
High melting and boiling points
Shiny in appearance
Malleable: Able to be hammered or pressed into shape without breaking or
cracking.
Ductile: Able to be drawn out into a thin wire.

4. PROPERTIES OF METALS
Metals exist as a lattice of positive ions in a ‘sea of electrons’. This
‘sea of electrons’ are mobile and able to carry electrical charges thus
giving metals the ability to conduct electricity.

5. ALLOYS

6. ALLOYS
An alloy is a mixture of a metal with another element.
Brass is a mixture of copper and zinc.
Stainless steel is a mixture of carbon and chromium.
Alloys are stronger than pure metals. This is because the different
sizes of atoms in an alloy disrupt the orderly arrangement of atoms
which means it harder for the atoms to slide past each other.

7. ALLOYS

8. REACTIVITY SERIES

9. REACTIVITY SERIES
Metals are arranged from the most reactive at the top to the least
reactive at the bottom.
They are determined by their reaction with cold water or steam, as
well as their reaction with hydrochloric acid.

10. REACTIVITY SERIES
Metal Symbol
Potassium K
Sodium Na
Calcium Ca
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Tin Sn
Lead Pb
*Hydrogen H
Copper Cu
Silver Ag
Gold Au
Most reactive
Least reactive
Mnemonics
Popular
Scientist
Can
Make
A
Zebra
In
The
Lab
He
Cannot
See
Girls

11. Metal(s) Observations and equation for reaction with cold water Observations and equation for reaction with steam
Potassium Reacts very violently, forms potassium hydroxide and
hydrogen gas.
2K(s) + 2H2O(l)  2KOH(aq) + H2(g)
React explosively. Never do this in the lab!
Sodium Reacts violently, forms sodium hydroxide and hydrogen
gas.
2Na(s) + 2H2O(l)  2NaOH(aq) + H2(g)
Calcium Reacts readily, forms calcium hydroxide and hydrogen
gas.
Ca(s) + 2H2O(l)  Ca(OH)2(aq) + H2(g)
Magnesium Reacts very slowly with cold water to form magnesium
hydroxide and hydrogen gas.
Mg(s) + 2H2O(l)  Mg(OH)2(aq) + H2(g)
Hot Magnesium reacts violently with steam to form magnesium oxide
(white solid) and hydrogen gas. A bright white glow is produced during
the reaction.
Mg(s) + H2O(g)  MgO(s) + H2(g)
Zinc No reaction occurs. Hot Zinc reacts readily with steam to form zinc oxide and hydrogen gas.
Zinc oxide is yellow when hot and white when cold.
Zn(s) + H2O(g)  ZnO(s) + H2(g)
Iron No reaction occurs. Hot Iron reacts slowly with steam to form iron oxide and hydrogen gas.
The iron must be heated constantly for the reaction to proceed.
3Fe(s) + 4H2O(g)  Fe3O4(s) + 4H2(g)
Lead
Copper
Silver
No reaction occurs. No reaction occurs.

12. REACTIVITY SERIES
If the metals do react with cold water,
General formula:
Metal + water  metal hydroxide + hydrogen
If the metals do not react with cold water but with steam,
General formula:
Metal + steam  metal oxide + hydrogen

13. Metal(s) Observation for reaction with dilute
hydrochloric acid
Equation
Potassium
React explosively. Never do this in the lab.
2K(s) + 2HCl(aq)  2KCl(aq) + H2(g)
Sodium 2Na(s) + 2HCl(aq)  2NaCl(aq) + H2(g)
Calcium Reacts violently to give hydrogen gas. Ca(s) + HCl(aq)  CaCl2(aq) + H2(g)
Magnesium Reacts rapidly to give hydrogen gas. Mg(s) + HCl(aq)  MgCl2(aq) + H2(g)
Zinc Reacts moderately fast to give hydrogen gas. Zn(s) + HCl(aq)  ZnCl2(aq) + H2(g)
Iron Reacts slowly to give hydrogen gas. Fe(s) + HCl(aq)  FeCl2(aq) + H2(g)
Lead
Copper
Silver
No reaction occurs. NA

14. EXTRACTION OF
METALS

15. EXTRACTION OF METALS
Most metals occur as compounds called ores found in the ground.
These ores are rarely in the pure state. We are only interested in the
metal elements and will obtain them using a process called
extraction.
The method used for extracting a metal from its ores depends on
the position of the metal in the reactivity series (Reactivity decreases
down the series).

16. EXTRACTION OF METALS
Metal Method of Extraction
Potassium
Sodium
Calcium
Magnesium
Aluminium
Electrolysis of their molten compounds.
Zinc
Iron
Tin
Lead
(Hydrogen)
Copper
Using coke (carbon) to reduce the metal oxide to obtain the
metal.
Silver
Gold
Found as free metallic elements

17. EXTRACTION OF METALS
Metals at the top of the series are very reactive and form very stable
compounds.
Electrolysis is used to obtain the metal.
Electrolysis is a costly method to extract metals as large amounts of
electricity is needed.

18. EXTRACTION OF METALS
Metals in the middle of the reactivity series usually exist as oxides or
sulfates.
The are extracted using reduction with carbon. The carbon will
remove the oxygen from the metal oxides to give the pure metal.
Carbon (Coke) is used cause it is cheap.

19. EXTRACTION OF METALS
Metals at the bottom of the reactivity series are least reactive. They
are found “native” in nature. For example Gold.

20. EXTRACTION OF IRON

21. EXTRACTION OF IRON
Iron is extracted from its ore called haematite or Iron (III) Oxide,
Fe2O3 by reduction with coke in a blast furnace.
This process removes oxygen from the haematite to give us the
pure iron.
We need limestone, coke and air for this process.

22. EXTRACTION OF IRON

23. EXTRACTION OF IRON
Coke: Carbon supply for reduction.
Hot air: Oxygen supply.
Limestone (Calcium Carbonate, CaCO3): To remove acidic impurities
(mainly sand) in the iron ore.

24. EXTRACTION OF IRON
Haematite, limestone and coke are added from the top.
Hot air blasted in from the bottom.
Haematite is reduced while all other impurities removed by the
Calcium oxide (which comes from limestone).

25. EXTRACTION OF IRON
Carbon reacts with oxygen from hot air to form carbon dioxide.
C(s) + O2(g)  CO2(g)
Carbon dioxide reacts with more carbon to form carbon monoxide.
CO2(g) + C(s)  2CO(g)

26. EXTRACTION OF IRON
Carbon monoxide reduces haematite to iron.
Fe2O3(s) + 3CO(g)  2Fe(l) + 3CO2(g)
Molten iron runs to the bottom of the furnace.

27. EXTRACTION OF IRON
Limestone decomposes to produce carbon dioxide and calcium
oxide.
CaCO3(s)  CaO(s) + CO2(g)
Calcium oxide is a basic oxide which reacts with acidic silicon
dioxide to form calcium silicate.
CaO(s) + SiO2(s)  CaSiO3(l)
Calcium silicate floats on molten iron.

28. EXTRACTION OF IRON
Calcium silicate, which is also known as slag, is used to make roads.
The molten iron obtained is further purified and processed.

29. RUSTING

30. RUSTING
Rusting or corrosion of iron is the process that produces rust.
Iron + oxygen + water  hydrated iron (III) oxide
4Fe(s) + 3O2(g) + 2xH20(l)  2Fe2O3.xH2O(s)

31. RUSTING
Conditions for rusting:
Both oxygen (air) and water are required.

32. RUST PREVENTION
Electroplating:
Coating iron with an layer of unreactive metal. For example,
platinum plating.
Painting or greasing:
Applying paint or oil on the iron’s surface.
Sacrificial protection:
A more reactive metal is attached to iron, and will be corroded first
before iron.

33. RECYCLING METALS

34. RECYCLING METALS
Why we need to recycle metals?
Metals are finite resources, which means they will run out some day.
How are metals recycled?
Metals are recovered from scrap metal.
Lead is recovered from car batteries.
Aluminum is recovered from food and drinks cans.

35. RECYCLING METALS
Advantages of recycling metals.
Conservation:
Recycling helps to conserve natural resources.
Recycling reduces environmental problems. We can minimize
mining and reduce destruction of huge amounts of land.
Economic:
Recycling might be cheaper than metal extraction from ores.

36. RECYCLING METALS
However, there are problems related to recycling.
Economic:
It can be expensive to separate metals from waste and incur
transportation costs, making recycling more expensive than
extracting metals.
Social issues:
Time and resources are spent to educate the public and a long time
before people will adopt a recycling lifestyle.

37. Permission is granted to you for personal use only. Contact
admin@basecamp.sg for commercial or school usage.