HALOGENALKANES

• What is a Halo alkane?

  An alkane with a halogen attached
• What is an example of a Halo alkane derived from methane?

  Chloromethane
• How is a Halo alkane formed from an alkane?

  By replacing a hydrogen with a halogen
• What is the process used to synthesize Halo alkanes?

  Free radical substitution
• What are the three steps of Halo alkane synthesis?

  1. Initiation step
  2. Propagation step (two stages)
  3. Termination step
• What is the first step in Halo alkane synthesis?

  Initiation step
• What occurs during the initiation step?

  A halogen molecule breaks down into free radicals
• What is the representation of a free radical?

  A single unpaired electron denoted by a dot
• What causes the halogen bond to break in the initiation step?

  UV light
• What is the result of the initiation step when chlorine is involved?

  Two chlorine free radicals are produced
• What happens during the first stage of the propagation step?

  A methane molecule reacts with a chlorine free radical
• What is formed when methane reacts with a chlorine free radical?

  Chloromethane and hydrogen chloride
• What is the role of the chlorine free radical in the propagation step?

  It acts as a catalyst
• How does the propagation step contribute to Halo alkane synthesis?

  It produces the Halo alkane through substitution
• What is the final step of Halo alkane synthesis?

  Termination step
• What occurs during the termination step?

  Two radicals combine to form a non-radical
• What is an example of a termination step involving chlorine radicals?

  Two chlorine radicals forming chlorine gas
• What is the significance of CFCs in relation to ozone depletion?

  CFCs release chlorine radicals that attack ozone
• Why were CFCs widely used before their ban?

  They were effective solvents and refrigerants
• What happens to CFCs when they reach the atmosphere?

  They break down under UV light
• Why is the carbon-chlorine bond more likely to break than the carbon-fluorine bond?

  The carbon-chlorine bond is weaker
• What is the consequence of ozone depletion?

  Increased UV radiation exposure
• What is the chemical formula for chlorofluorocarbons (CFCs)?

  Examples include CCl2F2 and CHClF2
• What is the role of ozone in the atmosphere?

  It filters UV radiation from the Sun
• What is the relationship between CFCs and skin cancer?

  Increased CFCs lead to more UV exposure
• What is the focus of this lesson?

  Nucleophilic substitution
• What is nucleophilic substitution classified under in AQA Chemistry?

  It is one of three mechanisms
• In which section of AQA Chemistry Unit 2 is nucleophilic substitution found?

  Haloalkanes
• What does the term 'nucleophile' break down into?

  Nuclear and file
• What does 'nucleo' relate to in the context of nucleophiles?

  It relates to positivity, like a nucleus
• What does the term 'substitution' mean in nucleophilic substitution?

  It means to swap
• What is the significance of bromine in bromoethane?

  Bromine allows nucleophilic attack
• Why does the carbon-bromine bond allow for nucleophilic substitution?

  Bromine is more electronegative than carbon
• What does the term 'Delta' imply in the context of charge?

  It indicates a difference in charge
• What is the definition of a nucleophile?

  An electron pair donor
• What does the double-headed arrow signify in nucleophilic substitution?

  Movement of a pair of electrons
• What happens to the carbon-bromine bond during nucleophilic substitution?

  Electrons move from the bond to bromine
• What are the three nucleophiles expected to be known in this unit?

  Hydroxide ion, cyanide ion, ammonia
• How does the hydroxide ion act as a nucleophile?

  It has a lone pair of electrons
• What product is formed when hydroxide ion attacks bromoethane?

  Ethanol