group 7

• Halogens ( Salt Forming)
• GROUP 7 : Halogens Physical Properties

  • They are non metals
  • They gain an electron to form -1 ions.
  • They have low melting and boiling points
  • Their melting point increases down the group due to increases in intermolecular forces.
  • They are found in pairs and exist as diatomic molecules (X2)
  • They are poisonous and smelly
  • Their reactivity increase down the group
  • Their density increases down the group.
  • They are poor conductors of heat and electricity
• HALOGEN REACTION X[F,Cl,Br,I]

  REACTION WITH HYDROGEN

  They react with hydrogen to form hydrogen halides.

  Reactivity decreases down the group so fluorine and chlorine reacts explosively and bromine and iodine reacts at higher temperature in the presence of catalyst.
• REACTION WITH METALS

  They react with metals to form ionic compounds. In Ionic compounds, halogens gain one electron from the metals to form -1 ions and attain noble gas electronic configurations.
• DISPLACEMENT REACTION

  The more reactive halogen displaces the less reactive halogen from its salt

  As the reactivity decreases down the group, the halogen at the top can take the position of the halogen at the bottom in its compounds and will displace the less reactive halogen.
• The Reactivity of Group 7 decreases down the group as the electron affinity or tendency to gain the electron decreases down the qroup. – React by gaining electron