PHYSICAL PROPERTIES OF HALOGENS
at room temp:-
Flourine and chlorine= GASES
Iodine = SOLID
Halogens are all coloured elements and are all TOXIC and CORROSIVE
- Halogens all have similar reactions because they're in the same group.
- All react with metals to form metal halides.
POTASSIUM + BROMINE >>>> POTASSIUM BROMIDE
2K (s) + Br2 (l) >>>>> 2KBr (s)
CALCIUM + CHLORINE >>>> CALCIUM CHLORIDE
Ca (s) + Cl2 (g) >>>>> CaCl2 (s)
Each halogen need ONE more electron to complete its outer shell, so they all form ions with a charge of -1. Flourine is the most reactive halogen and iodine is the least reactive.
MORE HALOGEN REACTIONS
Halogens and hydrogen
halogens react with hydrogen to form hydrogen halides.
These form acids when dissolved in water.
eg: flourine + water = hydrogen flouride.
-Bromine can be displaced from a solution of bromide salts by reacting them with CHLORINE.
sodium bromide + chlorine = sodium chloride + bromine
2NaBr (aq) + Cl2 (g) =2NaCl + Br2
Chlorine will also displace iodide ions and the solution will turn brown-black as iodine is formed.
REACTIVITY OF THE HALOGENS
If you add chlorine to a compound of fluorine, there will be no reaction.
Displacement reactions (see previous card) can be used to work out how reactive the different halogens are.
a more reactive halogen will displace a less reactive one.
Chlorine is more reactive than iodine so it displaces iodine.
Chlorine is also more reactive than bromine, so it displaces bromine from bromide.