Properties of Metals & Alloys (AQA GCSE Combined Science: Trilogy): Revision Note

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 

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 

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

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