1. Where do metals come from?

2. objectives
Most metals are found as chemical compounds (‘minerals’) in rocks
Rocks containing significant amount of particular minerals are called ores
How a metal is extracted from its ore depends on that metal’s position in the reactivity series
To some extent our human history is closely tied to the history of metal extraction

3. Much metal around?

4. Much metal around?

5. How easily a metal can be obtained depends on its reactivity…
potassium
sodium
lithium
calcium
magnesium
aluminium
zinc
iron
lead
copper
silver
gold

7. Gold is so unreactive that it can be found ‘native’ in the ground

8. Silver is also to be found in metallic form but you cant really pan for silver, it’s mined

9. Europe always had a lot of silver mines so it developed an economy based on silver coins

10. The blue colour is caused by the mineral copper carbonate

11. Copper, or bronze, reacts with CO2 over time to give a coating of copper carbonate, often called ‘verdigris’
Bronze is an alloy of copper and tin, stronger than pure copper

12. This is a rock called malachite.
It contains significant amounts of the mineral CuCO3.
A rock containing significant amounts of a metal compound is called an ore
Malachite is an ore, from which we can extract copper

13. This ore, cassiterite, contains tin oxide.
It is from this ore that tin is extracted.
Tin was obtained as long ago as copper was, back in an era of human history known as…

14. The Bronze Age
From about 2000BC

15. In 776 BC…
What would be the most valuable metal?
Second most valuable?
Third most valuable?

16. Most metals are found as compounds ‘minerals’ in rocks.
Rocks containing a significant amount of mineral are called ores.
Many metals are extracted from their ores by heating them with carbon.

17. Bauxite
Al2O3
Haematite
Fe2O3
Galena
PbS
Cinnabar
HgS
Malachite
CuCO3
Cassiterite
SnO2
Olivine
MgSiO4
Sphalerite
ZnS

18. Chemistry changes the world (early example)…
About 500BC the Iron Age came to Europe when the techniques of smelting were learned.
Iron ore is heated with charcoal in a furnace.
Iron is much stronger than bronze, you get wheels, saws to cut down trees, and stronger weapons with iron.

19. This rock contains a significant amount of iron oxide (that’s what gives it the rusty colour)
It is often called simply ‘iron ore’.

20. PbO2 + C  Pb + CO2 LEAD OXIDE + CARBON  LEAD + CARBON DIOXIDE
Reaction of lead oxide with carbon
LEAD OXIDE + CARBON  LEAD + CARBON DIOXIDE
PbO C  Pb CO2
LOST OXYGEN - REDUCTION
GAINED OXYGEN - OXIDATION

22. The Blast Furnace 2Fe2O3 + 3C  4Fe + 3CO2
Iron oxide is reduced by carbon into iron metal