Metals and alloys

• What type of structure do metals consist of?

  Giant structures of atoms arranged in a regular pattern
• What happens to the outer electrons of metal atoms in metallic bonding?

  The outer electrons become delocalised and can move freely
• How does the delocalisation of electrons contribute to metallic bonding?

  It results in strong metallic bonding due to shared electrons
• What are the properties of metals explained by their structure and bonding?

  • Electrical conductors due to delocalised electrons carrying charge
  • Good conductors of thermal energy as delocalised electrons transfer energy
  • High melting and boiling points due to strong metallic bonding
• What is an alloy?

  A mixture of two or more elements, at least one being a metal
• Why are alloys often more useful than pure metals?

  Alloys can be made harder by adding another element
• What happens to pure iron when a small amount of tungsten is added?

  It becomes tool steel, which is harder than pure iron
• What are the types of steel and their properties?

  • Mild steel: Carbon and iron; easy to bend and pull into wires
  • Tool steel: Tungsten and iron; hard, can be heated to high temperatures
  • Stainless steel: Chromium and iron; hard, does not rust easily
• How does the structure of a pure metal affect its hardness?

  The layers of atoms can slide over each other easily, making it soft
• Why do alloys require a greater force to slide their layers compared to pure metals?

  Alloys have atoms of different sizes that distort the layers
• How does the distortion of the metal lattice structure in alloys affect their properties?

  • Greater force is required for layers to slide
  • Alloys are harder and stronger than pure metals
• What is the effect of applying force to a pure metal's layers?

  The layers may slide over each other easily
• What is the relationship between the force needed to slide layers in a metal and its hardness?

  A greater force indicates a harder and stronger metal
• How does the presence of different sized atoms in an alloy contribute to its strength?

  It distorts the layers, requiring more force to slide them