Ionic compounds: Bonds, Structure & Properties (Edexcel IGCSE Chemistry)

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Ionic bonding

  • The positive and negative charges are held together by the strong electrostatic forces of attraction between oppositely charged ions
  • This is what holds ionic compounds together

Oppositely charged ions attraction due to electrostatic attraction, IGCSE & GCSE Chemistry revision notes

Electrostatic forces hold the ions together in sodium chloride

Giant Ionic Lattices

  • Ionic compounds are made of charged particles called ions which form a giant lattice structure
  • Ionic substances have high melting and boiling points due to the presence of strong electrostatic forces acting between the oppositely charged ions
  • These forces act in all directions and a lot of energy is required to overcome themNaCl Lattice_ Ball + Ball & Stick, IGCSE & GCSE Chemistry revision notes

Strong electrostatic forces act in all directions in an ionic solid such as sodium chloride

  • Ionic compounds are usually solid at room temperature and are non-volatile 
  • They are usually water soluble as both ionic compounds and water are polar  substances

The Periodic Table - Hydration of Sodium Chloride, downloadable AS & A Level Chemistry revision notes

Ionic compounds are soluble in water because the ions are easily hydrated by polar water molecules

Exam Tip

Ions with higher charge have stronger electrostatic forces and will thus have higher melting and boiling points.

Conductivity & Ionic Compounds

  • For electrical current to flow there must be present freely moving charged particles such as electrons or ions
  • Ionic compounds can conduct electricity in the molten state or in solution as they have ions that can move and carry charge
  • They cannot conduct electricity in the solid state as the ions are in fixed positions within the lattice and are unable to moveMolten ionic substances conduct electricity, IGCSE & GCSE Chemistry revision notes

Molten or aqueous particles move and conduct electricity but cannot in the solid state

Exam Tip

Remember that in ionic lattice structures, positively charged and negatively charged ions are arranged in an alternating pattern.

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Stewart

Author: Stewart

Stewart has been an enthusiastic GCSE, IGCSE, A Level and IB teacher for more than 30 years in the UK as well as overseas, and has also been an examiner for IB and A Level. As a long-standing Head of Science, Stewart brings a wealth of experience to creating Topic Questions and revision materials for Save My Exams. Stewart specialises in Chemistry, but has also taught Physics and Environmental Systems and Societies.