Which material to use for a job depends on its properties, and those properties come from what the material is made of.
Metals can be put in order of how readily their atoms lose electrons to form positive ions. The more readily they do so, the more reactive the metal. A common order, most reactive first, is potassium, sodium, calcium, magnesium, aluminium, carbon, zinc, iron, tin, lead, hydrogen, copper, silver, gold.
Carbon and hydrogen are not metals but are included because their positions decide how a metal can be extracted and whether it reacts with acid. A more reactive metal displaces a less reactive one from its compound.
A metal below carbon in the reactivity series can usually be extracted from its oxide by heating with carbon, or with carbon monoxide, which takes the oxygen away. Iron is obtained from iron oxide this way in a blast furnace.
Metals above carbon, such as aluminium, magnesium and calcium, form oxides too stable to be reduced by carbon, so electrolysis must be used instead. Before practical electrolytic extraction was developed in the nineteenth century, aluminium was difficult and expensive to produce.
Gold is unreactive enough to occur naturally as the element rather than only in compounds, though it still has to be mined and purified.
Ceramics, such as pottery and glass, are hard, stiff and brittle, and many common ones are good electrical and thermal insulators.
Polymers are made of long-chain molecules. Depending on their structure they can be flexible or rigid. Many common polymers are light, water-resistant and good electrical insulators, so they are used for packaging and cable insulation.
Composites combine two materials so that the result is better than either alone: concrete is gravel in cement, fibreglass is glass fibres in resin, and both are far stronger than their matrix on its own.
