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CHEMISTRY · Stage 7 · Chapter 3: Metals and Non-Metals

Chemistry 3.7 Chapter 3 Review: Metals and Non-Metals

5 min read 7 parts Lesson 7 of 7

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3.7 Chapter 3 Review: Metals and Non-Metals — Alhussan International Academy — Chemistry (Stages 7–9) notes: Revise the properties of metals and non-metals, their explanation by structure, alloys and the choice of materials from Chapter 3.Metals — they are shiny, strong, dense, m…

  • Exceptions
  • Aluminium cables
  • Choosing a material
  • Why harder
  • Particle diagrams
  • Trade-offs

Part 1 of 7Metals and non-metals

  • Metals — they are shiny, strong, dense, malleable and ductile, with high melting points, and conduct heat and electricity.
  • Non-metals — they are generally dull, brittle, poor conductors with lower melting points.
PropertyMetalNon-metal
Conducts electricityYesNo (graphite does)
MalleableYesNo
Melting pointHighMostly low
  • Exceptions — graphite conducts, mercury is a liquid metal, sodium is soft and diamond is hard.

Part 2 of 7Explaining properties by structure

  • Metals — a lattice of positive ions is held by a sea of delocalised electrons, which carry charge and energy and allow layers to slide.
    • Delocalised electrons are free to move, whereas all matter has electrons.
    • The ions, not the atoms, are positive.
  • Non-metals — most consist of small molecules with weak forces between the molecules, which explains low melting points and gaseous states.

Part 3 of 7Definitions

  • Malleable able to be hammered into shape.
  • Ductile able to be pulled into wires.
  • Sonorous making a ringing sound when hit, for example copper bells.
  • Lustrous shiny.
  • Composite a material made of two or more materials combined.
  • Density mass ÷ volume.

Part 4 of 7Uses and choosing metals

  • Steel — an iron alloy used for cars because it is strong.
  • Copper — it is used for wires because it conducts well and is ductile.
  • Aluminium cables — long-distance electricity cables are made from aluminium rather than gold, although gold is the better conductor, because gold is far more expensive and denser.
  • Saucepans — metal conducts heat and plastic handles insulate.
  • Choosing a material — link the property to the need and consider cost, mass, strength and corrosion.
    • Bicycle frames, wires and pans are common examples.

Part 5 of 7Conductors and fair tests

  • Fair testonly the material changes and the variables kept the same are the control variables.
  • Metals conduct well because of free electrons.
  • Examplein a comparison of the strength of four wires of different metals or alloys, the type of wire is the independent variable.

Part 6 of 7Alloys

  • Alloy — a mixture of a metal with another element.
  • Why harder — differently sized atoms stop layers sliding.
    • Steel is iron and carbon, brass is copper and zinc, and bronze is copper and tin.
  • Particle diagrams — a pure metal has identical atoms in rows while an alloy has atoms of different sizes.

Part 7 of 7Linking the ideas

  • Structure explains properties, and properties decide uses.
  • Metallic bonding leads to conductivity and malleability.
  • Weak forces between small molecules lead to low melting points.
  • Trade-offs — cost, mass and environmental impact decide the final choice.
  • Full answer — give the property, the particle explanation and the link to the use.

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