- These are non-metals
- They exsit as diatomic molecules (as two molecules).
- There are 7 electrons in their outershell.
- Halogens react by gaining 1 electron to make a full outershell (opposite to Group 1 - Alkali metals in every aspect).
Cl + 1 electron → Cl-
- Going down the group the outershell is further away from the nucleus.
- This is why reactivity decreases going down the group.
- Reactivity can be seen by a displacement reaction between the halogens & the halide ions.
Chloride water - Cl2(aq) → colourless most reactive
Bromine water - Br2(aq) → orange
Iodine solution - I2(aq) → brown least reactive
Halides (all colourless):
Sodium chloride solution - NaCl → Cl-(aq) most reactive
Sodium bromide solution - NaBr → Br-(aq)
Sodium iodide solution - NaI → I-(aq) least reactive
- A more reactive halogen will displace a less…