Edexcel IGCSE Chemistry

Revision Notes

1.6 5 Ionic compounds: Bonds, Structure & Properties

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 stronelectrostatic 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.

Author: Francesca

Fran has taught A level Chemistry in the UK for over 10 years. As head of science, she used her passion for education to drive improvement for staff and students, supporting them to achieve their full potential. Fran has also co-written science textbooks and worked as an examiner for UK exam boards.
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