Properties of Metals & Alloys (AQA GCSE Chemistry: Combined Science)

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Properties of metals

  • Metallic bonds are very strong and are a result of the attraction between the positive metal ions and the negative delocalised  electrons within the metal lattice structure

The structure of a metal 

Structure & bonding in a metal,

The properties of a metal

  • Most metals have high melting and boiling points 
    • There are strong electrostatic forces of attraction between the positive metal ions and the negative delocalised electrons within the metal lattice structure
    • These needs lots of energy to be broken 
  • Most metals are malleable
    • This means they can be hammered into shape
    • This is because the atoms are arranged in layers which can slide over each when force is applied 

The properties of metals 

Diagram showing rows of atoms moving over each other in a pure metal

When a force is applied, the layers of positive ions slide over each other

Properties of alloys

What is an alloy?

  • 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
  • Alloys often have properties that can be very different from the metals they contain
    • They can be stronger and harder
    • They are resistance to corrosion or extreme temperatures
  • These enhanced properties can make alloys more useful than pure metals

Why are alloys harder than pure metals?

  • Alloys contain atoms of different sizes so the layers become distorted 
  • This makes it more difficult for the layers of atoms to slide over each other, so alloys are usually much harder than the pure metal

Structure of an alloy

Structure of alloy showing atoms of different sizes

Particle diagram showing a mixture of elements in an alloy. The different sizes of the two types of atoms prevent the layers of atoms from sliding over each other, so the alloy becomes less malleable than the pure metal

Examiner Tip

Mark schemes for answers on why alloys are harder than pure metals are very specific. 

You must refer to atoms or ions throughout your answer- particles is not sufficient. 

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Stewart

Author: Stewart

Expertise: Chemistry Lead

Stewart has been an enthusiastic GCSE, IGCSE, A Level and IB teacher for more than 30 years in the UK as well as overseas, and has also been an examiner for IB and A Level. As a long-standing Head of Science, Stewart brings a wealth of experience to creating Exam Questions and revision materials for Save My Exams. Stewart specialises in Chemistry, but has also taught Physics and Environmental Systems and Societies.