Chemistry-Metals and their uses

Extracting metals

• Metals are usually found in the Earth's crust. They are often combined chemically with other elements such as oxygen
• An ore contains enough metal to make it worth extracting the metal
• The method we use to extract a metal depends on its reactivity
• Unreactive metal are found in the Earth as the metal
• The oxides of metal less reactive than carbon can be reduced using carbon
• A reduction reaction takes place as carbon removes the oxygen from the oxide to produce the metal. This method is used commercially if possible

Iron and steels

• Iron oxide is reduced in a blast furnance to make iron 
• Iron from the blast furnance is too brittle for many uses
• Most iron is converted into alloys called steels
• Steels contain carefully controlled quantities of carbon and other elements

Aluminium and titanium

• Aluminium and titanium resist corrosion. They also have low densities compared with other strong metals
• Aluminium and titanium cannot be extracted from their oxides using carbons
• Aluminium and titanium are expensive because extracting them involves many stages and requires large amounts of energy

Extracting copper

• Most copper is extracted from copper-rich ores by smelting
• Copper can be purified by electrolysis
• Bioleaching and phytomining are new ways to extract copper from low-grades ores
• Copper can be obtained from solutions of copper salts by displacement or electrolysis

Useful metals

• The transition metals are found in the central block of the periodic table
• Transistion metals have properties that make them useful for building and making things
• Most of the metals we use are alloys
• Copper is a very good conductor of heat and does not react with water. It can be bent but it is hard enough to keep its shape
• Most of the metals we use are not pure elements
• Pure iron, copper, gold and aluminium are soft and easily bent. They are often mixed with other elements to make alloys that are harder so that they keep their shape
• Iron is made into steel
• Gold used for jewellery is usually an alloy
• Most of the aluminium used for buildings and aircrafts is alloyed
• Copper alloys include bronze and brass

Metallic issues

• There are social, economic and environmental issues associated with exploiting metal ores
• Recycling saves energy and limited resources
• There are drawbacks as well as benefits from the use of metalsin sturctures
• Advantages of using metals in constructions:
• They are strong
• They can be bent into shape
• They can be made into flexible wires
• They are good electrical conductors
• Drawbacks of using metals in consturctions:
• Obtaining metals from ores causes pollution and uses up limited resources
• Metals are more expensive than other materials such as concrete
• Iron and steel can rust