GCSE · Chemistry · AQA · Spec 8462
Group 7 halogens
Build the Group 7 picture
Move from shared structure to trends and displacement.
- Start with sevenEvery Group 7 halogen has seven electrons in its outer shell, which links the group to similar reactions.
- Picture pairsHalogens are non-metals whose molecules consist of pairs of atoms, so they are diatomic molecules.
- Follow the physical trendsGoing down Group 7, relative molecular mass, melting point and boiling point all increase.
- Reverse for reactivityUnlike those three increasing trends, reactivity decreases going down Group 7.
- Use the reactivity orderA more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt.
- Turn trends into predictionsA position further down Group 7 lets you predict higher relative molecular mass, melting point and boiling point, but lower reactivity.
Relationship matrix
Tap any cell to reveal it. Tap a column header to read one property down every item.
Each cell hides a short answer and the reason behind it. Predict before you tap.
Predict the displacement
Commit to the reactivity rule before revealing the answer.
Halogen A is more reactive than halogen B. What happens when A is added to an aqueous solution of a salt containing B?
Chlorine, bromine and iodine reactions
The required comparison includes reactions with both metals and non-metals.
Group 7 essentials
Keep the core vocabulary tied to the trends.
WHAT YOU'VE LEARNED
A quick recap of today's lesson.
Connect seven outer-shell electrons to halogen behaviour, trends and displacement.
Learning with Lightbulb is opening soon
You can use this lesson now. Join the waitlist and we'll let you know when the full Lightbulb experience is ready.
Keep me postedMore AQA GCSE Chemistry topics
- Alternative methods of extracting metals (HT)
- Atmospheric pollutants from fuels
- Atom economy
- Atoms, elements and compounds
- Calculating rates of reactions
- Carboxylic acids (chem only)
- Cells and batteries (chem only)
- Chemical bonds (ionic, covalent, metallic)
- Collision theory and activation energy
- Concentration in mol/dm3 (chem HT)
- Conservation of mass and balanced equations
- Covalent bonding
How this lesson was checked. This AQA GCSE Chemistry (specification 8462)lesson was published through Lightbulb Learning's human-designed editorial process — the educational standards, accuracy rules and publication checks it must pass were authored and approved by Philip Halpin. It passed subject-specific assessment, automated educational checks and technical publication verification before going live (publication checks completed 12 August 2026). Published pages are monitored, human spot-checking is ongoing across the lesson library, and anything found wrong is corrected or withdrawn. How our lessons are made and checked. Spotted a mistake? Email hello@lightbulblearning.co and we'll review it.