- The Halogens are found in Group 7 of the Periodic Table.
- They are all brittle and crumble as solids.
- They form poisonous and pungent vapours.
- As you go down the group they get darker.
- They all have relatively low boiling and melting points; as you go up the group the lower the mp and bp get.
- Bromine at room temperature is a liquid and Iodine is a solid; however they are volatile and form vapours at relatively low temperatures.
- Iodine sublimes to form a purple vapour and is a dark-grey solid, Bromine is a brown liquid and boils to form a red-brown vapour. Chlorine is a green gas and flourine is a pale yellow gas.
- They can react with metals to form ionic compunds by gaining an electron to become a 1- anion.
- They all have 7 electrons in their outer shell.
- They can undergo displacement reactions where a more reactive halogen will displace a less reactive one.
- They can undergo reactions with Hydrogen but as you go down the group higher temperatures are required for it to take place.
- They exist as diatomic molecules covelantly bonded together in nature.

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The Periodic Table GCSE Topic