This guide covers IGCSE Chemistry bonding and structure. You will revise ionic bonding (metal + non-metal; transfer of electrons; giant lattice), covalent bonding (sharing electrons; simple molecules or giant), metallic bonding (positive ions in sea of electrons), and properties linked to structure.

Key concepts to revise

• Ionic – Metal loses electrons; non-metal gains; oppositely charged ions; giant lattice; high m.p.; conducts when molten/dissolved (ions free to move).
• Covalent – Non-metals share pairs of electrons; simple molecules (e.g. H2O, CO2) or giant (e.g. diamond, SiO2); simple molecules: low m.p.; do not conduct.
• Metallic – Positive metal ions in sea of delocalised electrons; malleable; conducts heat and electricity; high m.p. (varies).
• Dot-and-cross – Show outer electrons only; ionic: brackets and charges; covalent: shared pair between atoms.

Exam tips and command words

• Describe – The bonding in a given compound (ionic/covalent/metallic) and how it forms (transfer/sharing/sea of electrons).
• Draw – Dot-and-cross diagram for ionic (e.g. NaCl) or covalent (e.g. H2O, O2) molecule.
• Explain – Why ionic compounds conduct when molten but not solid (ions must be free to move); why covalent molecules have low m.p. (weak forces between molecules).
• State – One property of ionic, covalent (simple) and metallic substances.

Common mistakes

• Drawing covalent bond as transfer of electrons (covalent = sharing).
• Saying ionic compounds conduct in solid state (they conduct when molten or dissolved; ions fixed in solid).
• Not stating that melting point and conductivity depend on structure (giant vs simple; ions vs molecules).

Revision checklist

• Draw dot-and-cross for one ionic compound (e.g. NaCl) and one covalent molecule (e.g. H2O).
• State the type of bonding in a compound from its formula (metal + non-metal → ionic; non-metal only → covalent).
• Explain why ionic compounds have high m.p. and conduct when molten.
• Compare the bonding and properties of ionic, covalent (simple) and metallic substances.

Next steps

Book a free trial with an IGCSE Chemistry tutor to practise bonding and structure questions, or explore Tutopiya’s learning portal for more revision resources.