Sodium chloride lattice model with magnets and water molecules
The ions are printed as hemispheres with different numbers of round sides, flat sides (to glue together) and sides with indentations for magnets.
chloride ions and oxygen atom: 8 x 3 mm
sodium ions and hydrogen atoms: 5 x 1 mm
I use the model to make lattice energy and hydration energy more palpable, as well as to show the orientation of the water molecules coordinated to the ions.
- Coulomb force
- definition of ions
- definition of dipole molecules
- The formation of a lattice is an exothermic process.
- Moving ions away from each other is an endothermic process.
- The coordination of water molecules to ions is an exothermic process.
- The orientation of water molecules coordinated to an ion depends on whether the ion is positively or negatively charged.
Different options to incorporate the model into your lessons:
- Show the formation of a salt and use the model to explain why the process is exothermic. You could then continue with the Born-Haber cycle.
- Explain why high temperatures are required to melt salts.
- Explain why high temperatures are not required when dissolving salts.
- Let students dissolve NaCl, KNO3 and CaCl2 while measuring temperature and explain endo- and exothermic heat of solution using the model.