2. Extraction and Uses of Metals

• Metals are found in the Earth’s crust as ores — rocks containing enough metal to be worth extracting. • Most metals are combined as oxides and extracted by reduction (removing oxygen) using electrolysis, a blast furnace, or a more reactive material. • Common ores: haematite (iron) and bauxite (aluminium). - Unreactive metals like gold and platinum are found as pure elements due to their stability.

They aren’t, they are found as pure elements

• Extracted by heating with a reducing agent such as carbon or carbon monoxide in a blast furnace • A cheap process as carbon is cheap and can also be a source of heat

• Extracted by electrolysis of the molten chloride or oxide • Large amounts of electricity are required, which makes this an expensive process

• Aircraft bodies: High strength-to-weight ratio (low density) • Saucepans: Very good conductor of heat and unreactive • Overhead electrical cables: Very good conductor of electricity • Food cans: Non-toxic, resistant to corrosion and resistant to acidic foodstuffs

• Electrical wiring: Very good conductor of electricity and ductile • Saucepans: Very good conductor of heat, unreactive, malleable • Water pipes: Unreactive (does not react with water), non-toxic and malleable

• Building material: Good strength, malleable and ductile, relatively inexpensive • Catalyst: Variable oxidation state, increases the rate of reaction without being used up

0.25% C (Car body panels and wiring): Soft and malleable

0.5–1.4% C (Tools, e.g. chisels): Hard

20% Cr and 10% Ni (Cutlery, sinks and chemical plants): Strong and resistant to corrosion

• An alloy is a mixture of two or more metals or metal with a non-metal such as carbon • Steel is made from iron and carbon

• They can be stronger and harder • They are resistance to corrosion or extreme temperatures

• Alloys contain atoms of different sizes • This distorts the regular arrangements of atoms • So it is more difficult for the layers of atoms to slide over each other