Giant ionic structures
3 marks · EasyMagnesium fluoride (MgF_2) is an ionic compound with a giant ionic lattice.
State the type of structure present in magnesium fluoride.
Explain why magnesium fluoride does not conduct electricity when solid.
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(a) Giant ionic lattice
(b) Ions are not free to move in the solid, so cannot carry charge. · must show Ions are in fixed positions, No free movement of ions, No conduction
Common mistakes: Saying ions are free in solids
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Marking points
B1 (a) · 1 mark · Identifies 'giant ionic lattice' as the structure type for magnesium fluoride
M1 (b) · 1 mark · States ions are in fixed positions or cannot move in solid state
A1 (b) · 1 mark · Links lack of movement to inability to conduct electricity
Worked solution
a) Magnesium fluoride has a giant ionic lattice structure.
b) In the solid state, the ions are held in fixed positions and cannot move. Because the ions cannot move, magnesium fluoride does not conduct electricity when solid.