Cells and extraction
The last two uses of the activity series — electrochemical cells and metal extraction — both flow from the same idea.
Metal extraction
Separating a metal from the natural ore that contains it is called metal extraction. The activity series can be used to decide the method suitable for extracting a metal.
Reactivity fixes how a metal occurs in nature
According to their reactivity, the way metals occur in nature also differs — and that in turn tells us how hard they are to extract.
Top — as compounds
Reactive metals such as sodium (Na) and potassium (K) cannot be found as free elements in the natural environment. They occur combined, as very stable ionic compounds.
Middle — as compounds, more easily freed
Metals of moderate reactivity such as iron (Fe), tin (Sn), zinc (Zn) and lead (Pb) also occur as compounds.
Bottom — as the free metal
Metals of low reactivity such as silver (Ag), gold (Au) and platinum (Pt) occur naturally as the free metal itself, mixed with other constituents.
The rule
The more reactive a metal, the harder it is to separate from its compound. So metals high in the series need powerful methods and those low in it need easy ones.
In the next section we look at those three methods and describe the extraction of iron and of gold.