Ionic Bonding

OCR

GCSE

Ionic bonding constitutes the strong electrostatic attraction between positive metal ions and negative non-metal ions, resulting from the transfer of electrons to achieve stable noble gas configurations. These ions arrange themselves into a giant ionic lattice, a regular repeating structure that extends in all directions, maximizing attraction and minimizing repulsion. Candidates must articulate how this lattice structure dictates physical properties, specifically the high energy required to overcome strong bonds during melting and the necessity of mobile ions for electrical conductivity.

Objectives

Exam Tips

Pitfalls

Key Terms

Mark Points

What You Need to Demonstrate

Key skills and knowledge for this topic

Award 1 mark for explicitly stating that electrons are transferred from the metal atom to the non-metal atom
Credit responses that define the structure as a 'giant ionic lattice' held together by strong electrostatic forces
Award 1 mark for explaining that ions are free to move and carry charge only when molten or in aqueous solution
Credit the identification of model limitations, such as 'dot-and-cross diagrams do not show the 3D arrangement of the lattice'

Example Examiner Feedback

Real feedback patterns examiners use when marking

"You correctly identified the bond type, but referred to 'intermolecular forces' — remember, ionic bonds are electrostatic attractions within a giant lattice."
"Your dot-and-cross diagram is accurate; ensure you include square brackets and the charge outside the bracket to secure full marks."
"Good explanation of conductivity. To reach the top band, explicitly state that 'ions' are free to move, not 'electrons'."
"When evaluating the model, extend your answer to mention that the diagram does not show the vibration of ions or the correct scale."

Marking Points

Key points examiners look for in your answers

Award 1 mark for explicitly stating that electrons are transferred from the metal atom to the non-metal atom
Credit responses that define the structure as a 'giant ionic lattice' held together by strong electrostatic forces
Award 1 mark for explaining that ions are free to move and carry charge only when molten or in aqueous solution
Credit the identification of model limitations, such as 'dot-and-cross diagrams do not show the 3D arrangement of the lattice'

Examiner Tips

Expert advice for maximising your marks

💡When explaining high melting points, you must link 'strong electrostatic forces' to the 'large amount of energy' required to overcome them
💡In 6-mark Level of Response questions, clearly distinguish between the solid state (ions fixed) and liquid state (ions mobile) to access the top band
💡Memorise the charges of common polyatomic ions (sulfate, nitrate, carbonate, hydroxide) as these are frequently required for formula prediction

Common Mistakes

Pitfalls to avoid in your exam answers

Referencing 'weak intermolecular forces' when explaining the melting point of ionic compounds (automatic zero for that point)
Stating that 'electrons' move to carry charge in molten ionic compounds, rather than 'ions'
Drawing shared electrons (covalent style) in the overlap region instead of separate ions with brackets and charges

Key Terminology

Essential terms to know

Electron transfer and stable electronic configurations

Electrostatic forces of attraction

Giant ionic lattice structure

Limitations of bonding models (dot-and-cross, ball-and-stick)

Likely Command Words

How questions on this topic are typically asked

Explain

Draw

Predict

Evaluate

Calculate

Compare

Practical Links

Related required practicals

•{"code":"PAG C3","title":"Electrolysis","relevance":"Demonstrates the conductivity of ionic compounds in molten/aqueous states"}

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