KA 1: Homologous Series

• What is a homologous series?

  A group of molecules with similar properties
• What groups are included in National 5 Chemistry's homologous series?

  Alkanes, alkenes, cycloalkanes, alcohols, carboxylic acids
• What is a hydrocarbon?

  A molecule containing hydrogen and carbon
• How does the name of a hydrocarbon depend on its structure?

  It depends on the number of carbon atoms and functional groups
• What is the prefix for one carbon atom in hydrocarbons?

  Meth
• What is the prefix for two carbon atoms in hydrocarbons?

  Eth
• What is the prefix for three carbon atoms in hydrocarbons?

  Prop
• What is the prefix for four carbon atoms in hydrocarbons?

  But
• What is the prefix for five carbon atoms in hydrocarbons?

  Pent
• What is the prefix for six carbon atoms in hydrocarbons?

  Hex
• What is the prefix for seven carbon atoms in hydrocarbons?

  Hept
• What is the prefix for eight carbon atoms in hydrocarbons?

  Oct
• What are alkanes characterized by?

  Single bonds between carbon and hydrogen
• How do the names of alkanes end?

  In -ane
• What is the chemical formula for alkanes?

  $C_nH_{2n+2}$
• What are branched alkanes named based on?

  The closest side to the branch
• What distinguishes alkenes from alkanes?

  Alkenes have a carbon-to-carbon double bond
• What does it mean for alkenes to be unsaturated?

  They contain a carbon-to-carbon double bond
• What can unsaturated molecules undergo?

  Addition reactions
• What is the chemical formula for alkenes?

  $C_nH_{2n}$
• What are cycloalkanes?

  A homologous series with a cyclic structure
• What are cycloalkanes in relation to alkenes?

  They are isomers of alkenes
• What are isomers?

  Chemicals with the same formula but different structures
• How do cycloalkanes and alkenes relate in terms of carbon count?

  They have the same number of carbons
• What are addition reactions?

  When a double bond adds onto an unsaturated molecule
• How can you test if a molecule is unsaturated?

  Using bromine solution to check for decolourisation
• What indicates that a substance is unsaturated when using bromine solution?

  Decolourisation of the solution
• What are the key points about homologous series and hydrocarbons?

  • Homologous series: similar chemical properties
  • Naming based on carbon atoms:
  • 1 = Meth
  • 2 = Eth
  • 3 = Prop
  • 4 = But
  • 5 = Pent
  • 6 = Hex
  • 7 = Hept
  • 8 = Oct
• What are the key characteristics of alkanes and alkenes?

  • Alkanes:
  • Single bonds
  • Ends in -ane
  • Formula: $C_nH_{2n+2}$
  • Alkenes:
  • Double bonds
  • Unsaturated
  • Formula: $C_nH_{2n}$
• What are the key points about isomers and addition reactions?

  • Isomers: same formula, different structures
  • Addition reactions: double bond adds to unsaturated molecule
  • Test for unsaturation: bromine solution decolourisation