Cambridge IGCSE Chemistry · Syllabus 0620 · The Periodic Table
Halogen Reactivity Order
What is Halogen Reactivity Order?
The order of chemical reactivity of the halogens, which decreases down Group VII, so chlorine is more reactive than bromine and bromine is more reactive than iodine. This order is the single fact that decides every halogen displacement reaction: a halogen higher in the group displaces the halide ion of one lower down.
This definition is part of the The Periodic Table chapter in Cambridge IGCSE Chemistry.