Group 17 reactions

• What kills bacteria in bleach?

  The HCl and ClO- not chlrone
• Chlorine and concentrated sodium hydroxide

  3Cl2 + 6NaOH -> 5NaClO3 + 2H2O + 3NaCl
• Chlorine and dilute sodium hydroxide


  2NaOH + Cl2 -> NaClO + NaCl + H2O (forms bleach)
• Cons of using chlorine to treat water

  Toxics, poisonous, forms carcinogens
• Pros of using chlorine to treat water

  Kills bacteria, purifies and steralises water
• Disproportionation reactions


  occur when one element undergoes both oxidation and reduction
• Displacements of Halogens

  F displaces Cl, Br and I
• Why does fluorine have the greatest tendency to attract an electrons?

  Smallest atomic radius, least amount of shielding and the nuclear attraction towards an electron from a halide ion is the greatest
• Displacement reactions of halogens

  A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt
• melting + boiling points of halogens

  Increases down the group, London forces become stronger since there are more electrons and more energy needed to break the bonds between the halogens increases down the group
• Intermolecular forces between the halogens?

  London Forces
• What is the molecular structure of the halogens?

  Simple and covalently bonded by sharing one electron
• Are all halogens diatomic?

  YES
• Group 17 reacting with sodium

  Halogen gains electrons, formation of bond between nucleus of the atom and electron releases energy, down group 17 the amount of energy released increases, the oxidation power of the halogens decreases
• sodium + halogen equation

  2Na + X2 —> 2NaX
• reactivity of halogens

  Decreases down the group