properties of metals
1) Describe the general physical properties of Metals
- High density.
- Shiny when polished.
- Malleable: layers of atoms are able to slide over each other.
- High m.p. and b.p.: strong metallic bonding.
- Good conductor of heat & electricity: because of de-localised electrons in their structure.
2) Describe Metallic Bonding
- A lattice of positive ions in a ‘sea of electrons’.
- Metal atoms are held strongly to each other by metallic bonding.
- In the metal lattice, the atoms lose their valence electrons and become positively charged.
- The valence electrons no longer belong to any metal atom and are said to be delocalised.
- They move freely between the metal ions like a sea of electrons.
3) Describe Alloys
- Mixture of a metal with other elements.
- Alloys are used because they have improved qualities for a particular job over the pure metals.
- Brass, a mixture of Copper and Zinc. Brass is stronger and more resistant to corrosion. Commonly used in electrical fittings, car radiators.
- Stainless Steel, a mixture of Iron, Chromium and Nickel. Stainless steel does not rust. Commonly used in kitchen sinks and cutlery.
Metals are often used as alloys because they have an increased range of uses and mixture of atoms gives an
irregular structure which stops layers sliding over each other easily; they are stronger.
4) Describe the Reactivity Series
Reaction with water/steam and dilute hydrochloric acid
Reduction of their oxides with carbon
5) Displacement Reactions
- The more reactive metal will displace the less reactive metal from the anion.
- The bigger the difference in reactivity between the two metals, the faster the reaction.
extraction of metals from their ores
6) Describe the Extraction of Iron from Hematite in the Blast Furnace
carbon + oxygen → carbon dioxide
carbon dioxide + carbon → carbon monoxide
iron(III) oxide + carbon monoxide → iron + carbon dioxide
calcium carbonate + silicon dioxide → calcium silicate + carbon dioxide
Uses of slag:
- To make roads
- To make cement
7) Extraction of Aluminum from Bauxite by Electrolysis
- Aluminum is a reactive metal which sits above carbon on the reactivity series.
- It cannot be extracted from its ore (bauxite) by carbon reduction, so electrolysis is used.
- Cryolite is added to lower the melting point to reduce some of the costs in extracting aluminum.
uses of metals
- Manufacture of airplane/cars (strong/low density/resistant to corrosion).
- Food containers (resistant to corrosion/malleable).
- Overhead cable (good conductor of electricity/ductile).
- Galvanizes iron: iron or steel coated with protective layer to zinc, zinc is oxidised instead of iron/steel, sacrificed to keep iron/steel from rusting.
- Make alloys: zinc + copper = brass
10) Mild Steel and Stainless Steel
- Mild steel: tough, ductile, malleable, good tensile strength, for car bodies & machinery.
- Stainless steel (chromium & iron alloy): resistant to corrosion, for chemical plant & cutlery.
9) Why recycle metals
- There is a limited supply of every material on Earth.
- Mining and extraction use up valuable fossil fuels, which contributes to climate change.