Figure: Part of a magnesium chloride structure

Which limitation applies to this model?
It should show covalent bonds joining the ions together
It should show the particles as neutral atoms, not ions
It should show both types of ion as exactly the same size
It should show that the lattice extends much further
56 exam-style questions on Edexcel GCSE Chemistry 2.3 Ionic bonding, covering 2.3.1 Ions and the formation of ionic bonds, 2.3.2 Naming and deducing formulae of ionic compounds, and 2.3.3 Giant ionic lattices. Each one has a worked solution and a mark scheme showing where the marks go.