7.1.1 Crude Oil, Hydrocarbons & Alkanes

• Carbon

  • Always forms four covalent bonds
  • Bonds can be single, double or triple
• Alkanes

  Have the general formula CnH2n+2
• Crude oil


  • Finite resource found in the Earth's crust
  • Complex mixture of compounds, mainly hydrocarbons
  • Also contains natural gas
  • Thick, sticky, black liquid found in porous rock
• Crude oil formed over millions of years from the effects of high pressures and temperatures on the remains of biomass (plants and animals), mainly plankton that was buried in mud
• Alkanes


  • Group of saturated hydrocarbons
  • Saturated means only single carbon-carbon bonds, no double bonds
  • Colourless compounds
  • Physical properties change as number of carbon atoms increases
• Alkanes


  • Generally unreactive
  • Undergo combustion reactions
  • Can be cracked into smaller molecules
  • Can react with halogens in the presence of light
• Methane


  An alkane and the major component of natural gas
• As a homologous series ascends the size of the molecule increases and affects physical properties like boiling point and density