Halogens exist as diatomic molecules (pairs of atoms: F₂, Cl₂, Br₂, I₂)
| Halogen | Colour | State at RT |
|---|---|---|
| Fluorine (F₂) | Pale yellow | Gas |
| Chlorine (Cl₂) | Yellow-green | Gas |
| Bromine (Br₂) | Orange/brown | Liquid |
| Iodine (I₂) | Grey/purple vapour | Solid |
Trends down the group:
- Colour gets darker
- Melting/boiling points increase (gas → liquid → solid)
- Reactivity decreases
This key facts covers Physical Properties — Colour and State at Room Temperature within Group 7: Halogens for GCSE Chemistry. Revise Group 7: Halogens in Atomic Structure for GCSE Chemistry with 22 exam-style questions and 21 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 5 of 12 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Group 7: Halogens
How many electrons do halogens have in their outer shell?
Explain why chlorine is more reactive than bromine.
Quick recall flashcards
Cl₂ + 2KBr → ?
2KCl + Br₂ (chlorine displaces bromine)
Will Br₂ + NaCl react?
NO — bromine is less reactive than chlorine