This video explains Elements in the Earth's crust

Although there are over 100 elements, only about 9 of them appear in any quantity in the Earth's crust.
Obtaining metals from their ores

Iron is obtained by heating the ore with coke. Iron ore contains iron oxide and coke contains carbon and is made by heating coal. The carbon in the coke pulls away the oxygen from the iron ore, leaving molten iron.

[Note: other elements, eg zinc, could be used to reduce the iron, but they are expensive and the iron is more difficult to purify after].

Word equation: Aluminium is too high in the activity series to be reduced by heating it with carbon. Aluminium is obtained by a process called electrolysis, where an electric current is passed through the molten ore. This makes aluminium a lot more expensive than iron.

Copper is low in the activity (and can be found native as the free metal) but is usually obtained by heating its ore with carbon. Copper is purified by electrolysis which makes it an expensive metal.

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