A LevelChemistryCambridge (CIE)Revision Notes9. The Periodic Table: Chemical PeriodicityPeriodicity of Chemical Properties of the Elements in Period 3Period 3 Chlorides & Oxides

Period 3 Chlorides & Oxides (Cambridge (CIE) A Level Chemistry): Revision Note

Exam code: 9701

Written by: Philippa Platt

Reviewed by: Caroline Carroll

Updated on 2 July 2026

Bonding in Period 3 Chlorides & Oxides

Period 3 chlorides

Chemical bonding & structure of Period 3 chlorides table

Period 3 chloride	NaCl	MgCl₂	Al₂Cl₆	SiCl₄	PCl₅	SCl₂
Chemical bonding	Ionic	Ionic	Covalent	Covalent	Covalent	Covalent
Structure	Giant ionic	Giant ionic	Simple molecular	Simple molecular	Simple molecular	Simple molecular

Period 3 oxides

Chemical bonding & structure of Period 3 oxides table

Period 3 oxide	Na₂O	MgO	Al₂O₃	SiO₂	P₄O₁₀	SO₂SO₃
Chemical bonding	Ionic	Ionic	Ionic (with some covalent character)	Covalent	Covalent	Covalent
Structure	Giant ionic	Giant ionic	Giant ionic	Giant covalent	Simple molecular	Simple molecular

Going across Period 3, their chlorides and oxides become more covalent and their structure shifts from a giant ionic to a simple molecular structure
Their reactions with water become more vigorous as a result of this, as it becomes easier to hydrolyse the chlorides and oxides

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