Metals -uses of metals

The iron we get from a blast furnace is very impure. It contains about 96% iron. We call this pig iron.
If the iron was 100% pure iron it would be brittle and not very strong. This is because the layers are iron atoms can slide over each other easily. This iron would be easily shaped and soft. Too soft for most uses.
We can make the iron a lot stronger by adding small amounts of impurities. If we add small amounts of carbon to iron we get the alloy steel. The smaller carbon atoms make the layers less regular and so they cant slide over each other as easily. This makes the alloy harder.
Steel is strong, hard and tough. This makes it very useful for making lots of different things. By adding different amounts of carbon and other elements we can control the properties of the steel to get just what we want for a particular use. Low carbon steels are easily shaped High carbon steels are hard Stainless steels are resistant to corrosion

Many metals are much more useful when they are mixed with other things, e.g. another metal. These are called alloys.

Copper + Zinc = Brass                          (malleable and non-corrosive with good acoustic properties      
Copper + Tin = Bronze                          (used for casting as it does not oxidise below its surface)    
Nickel + Titanium = Nitinol                  (this is a shape memory alloy. It returns to its original shape after deformation.
Aluminium + Copper = Duralumin      (Much stronger than pure aluminium)
 

Many of these elements have properties which make them very useful for lots of different applications.

Copper has properties which make it very useful for electrical wiring and plumbing. It is extracted from its ore by using electricity (electrolysis). The supply of copper rich ore is limited so scientists are trying to find efficient ways of extracting copper form low grade ores.
Aluminium and titanium have low densities and are resistant to corrosion. They are expensive to extract from their ores because a lot of energy is needed and there are many stages in the process.