Group 7: The Halogens

This lesson covers Group 7 of the periodic table — the halogens — as required by AQA GCSE Chemistry specification (5.1.2). The halogens are reactive non-metals with distinctive properties. Understanding their physical properties, reactions, displacement reactions, and the trend in reactivity down the group is essential for GCSE Chemistry.

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The Halogens

Group 7 contains the following elements:

Element	Symbol	Atomic Number	Electronic Configuration	State at Room Temp	Colour
Fluorine	F	9	2, 7	Gas	Pale yellow
Chlorine	Cl	17	2, 8, 7	Gas	Green-yellow
Bromine	Br	35	2, 8, 18, 7	Liquid	Red-brown
Iodine	I	53	2, 8, 18, 18, 7	Solid	Dark grey/purple vapour
Astatine	At	85	(radioactive, very rare)	Solid	Dark (predicted)

Key Features of Halogens