GROUP 7

• The elements in group 7 are non-metals called the halogens.
• Their halogens show trends in their physical and chemical properties.

p h y s i c a l  properties

• CHLORINE,Cl2-pale green, gas
• BROMINE,Br2-brown, liquid 
• IODINE, I2-purple-black, solid
• the melting points and boiling points of the halogens increase going down group 7.
  
• the molecules become larger 
• more energy is needed to overcome these forces 

c h e m i c a l properties

• halogens have 7 electrons in their outer shell which means that they all have similar chemical properties
• reaction with metals- they react with metals to produce salts eg. sodium + chlorine→ sodium chloride 
• the halogens become less reactive going down the group.
• a more reactive halogen can displace a less reactive halogen from solutions of its salts.                          eg. chlorine is more reactive than iodine. A solution of chlorine can displace iodine from a potassium iodine solution solution=chlorine+potassium iodide→potassium chloride + iodine